temporarily change output to see if the comment works

.github/workflows/build-binaries.yml

@@ -377,7 +377,7 @@ jobs:
           args: --release --locked --out dist
       - name: "Test wheel"
         if: matrix.target == 'x86_64-unknown-linux-musl'
-        uses: addnab/docker-run-action@4f65fabd2431ebc8d299f8e5a018d79a769ae185 # v3
+        uses: addnab/docker-run-action@v3
         with:
           image: alpine:latest
           options: -v ${{ github.workspace }}:/io -w /io

.github/workflows/ci.yaml

@@ -237,13 +237,13 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-insta
       - name: Red-knot mdtests (GitHub annotations)
@@ -291,13 +291,13 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -320,7 +320,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-nextest
       - name: "Run tests"
@@ -376,7 +376,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - name: "Build"
         run: cargo build --release --locked
 
@@ -401,13 +401,13 @@ jobs:
           MSRV: ${{ steps.msrv.outputs.value }}
         run: rustup default "${MSRV}"
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - name: "Install cargo nextest"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-nextest
       - name: "Install cargo insta"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-insta
       - name: "Run tests"
@@ -433,7 +433,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install cargo-binstall"
-        uses: cargo-bins/cargo-binstall@63aaa5c1932cebabc34eceda9d92a70215dcead6 # v1.12.3
+        uses: cargo-bins/cargo-binstall@main
         with:
           tool: cargo-fuzz@0.11.2
       - name: "Install cargo-fuzz"
@@ -455,7 +455,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+      - uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
       - uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e # v4.2.1
         name: Download Ruff binary to test
         id: download-cached-binary
@@ -641,7 +641,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: cargo-bins/cargo-binstall@63aaa5c1932cebabc34eceda9d92a70215dcead6 # v1.12.3
+      - uses: cargo-bins/cargo-binstall@main
       - run: cargo binstall --no-confirm cargo-shear
       - run: cargo shear
 
@@ -681,7 +681,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+      - uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
       - name: "Cache pre-commit"
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
         with:
@@ -720,7 +720,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: Install uv
-        uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+        uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
       - name: "Install Insiders dependencies"
         if: ${{ env.MKDOCS_INSIDERS_SSH_KEY_EXISTS == 'true' }}
         run: uv pip install -r docs/requirements-insiders.txt --system
@@ -857,7 +857,7 @@ jobs:
         run: rustup show
 
       - name: "Install codspeed"
-        uses: taiki-e/install-action@09dc018eee06ae1c9e0409786563f534210ceb83 # v2
+        uses: taiki-e/install-action@be7c31b6745feec79dec5eb79178466c0670bb2d # v2
         with:
           tool: cargo-codspeed
 

.github/workflows/daily_fuzz.yaml

@@ -34,11 +34,11 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+      - uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
       - name: Build ruff
         # A debug build means the script runs slower once it gets started,

.github/workflows/daily_property_tests.yaml

@@ -36,7 +36,7 @@ jobs:
       - name: "Install Rust toolchain"
         run: rustup show
       - name: "Install mold"
-        uses: rui314/setup-mold@e16410e7f8d9e167b74ad5697a9089a35126eb50 # v1
+        uses: rui314/setup-mold@v1
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
       - name: Build Red Knot
         # A release build takes longer (2 min vs 1 min), but the property tests run much faster in release

.github/workflows/mypy_primer.yaml

@@ -26,6 +26,10 @@ jobs:
   mypy_primer:
     name: Run mypy_primer
     runs-on: depot-ubuntu-22.04-16
+    strategy:
+      matrix:
+        shard-index: [0, 1, 2]
+      fail-fast: false
     timeout-minutes: 20
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
@@ -35,7 +39,7 @@ jobs:
           persist-credentials: false
 
       - name: Install the latest version of uv
-        uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+        uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
 
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
         with:
@@ -64,6 +68,8 @@ jobs:
 
           cd ..
 
+          DIFF_FILE="mypy_primer_${{ matrix.shard-index }}.diff"
+
           echo "Project selector: $PRIMER_SELECTOR"
           # Allow the exit code to be 0 or 1, only fail for actual mypy_primer crashes/bugs
           uvx mypy_primer \
@@ -71,26 +77,31 @@ jobs:
             --type-checker knot \
             --old base_commit \
             --new "$GITHUB_SHA" \
+            --num-shards 3 --shard-index ${{ matrix.shard-index }} \
             --project-selector "/($PRIMER_SELECTOR)\$" \
             --output concise \
-            --debug > mypy_primer.diff || [ $? -eq 1 ]
+            --debug > $DIFF_FILE || [ $? -eq 1 ]
 
           # Output diff with ANSI color codes
-          cat mypy_primer.diff
+          cat $DIFF_FILE
 
           # Remove ANSI color codes before uploading
-          sed -ie 's/\x1b\[[0-9;]*m//g' mypy_primer.diff
+          sed -ie 's/\x1b\[[0-9;]*m//g' $DIFF_FILE
 
-          echo ${{ github.event.number }} > pr-number
+      - if: ${{ matrix.shard-index == 0 }}
+        name: Save PR number
+        run: |
+          echo ${{ github.event.pull_request.number }} | tee pr-number
 
       - name: Upload diff
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
-          name: mypy_primer_diff
-          path: mypy_primer.diff
+          name: mypy_primer_diffs-${{ matrix.shard-index }}
+          path: mypy_primer_${{ matrix.shard-index }}.diff
 
       - name: Upload pr-number
         uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        if: ${{ matrix.shard-index == 0 }}
         with:
           name: pr-number
           path: pr-number

.github/workflows/mypy_primer_comment.yaml

@@ -1,97 +1,96 @@
-name: PR comment (mypy_primer)
-
 on: # zizmor: ignore[dangerous-triggers]
   workflow_run:
-    workflows: [Run mypy_primer]
-    types: [completed]
-  workflow_dispatch:
-    inputs:
-      workflow_run_id:
-        description: The mypy_primer workflow that triggers the workflow run
-        required: true
+    workflows:
+      - Run mypy_primer
+    types:
+      - completed
+
+permissions: {}
 
 jobs:
   comment:
-    runs-on: ubuntu-24.04
+    name: Comment PR from mypy_primer
+    runs-on: ubuntu-latest
     permissions:
+      contents: read
       pull-requests: write
     steps:
-      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
-        name: Download PR number
+      - name: Download diffs
+        uses: actions/github-script@v7
         with:
-          name: pr-number
-          run_id: ${{ github.event.workflow_run.id ||  github.event.inputs.workflow_run_id }}
-          if_no_artifact_found: ignore
-          allow_forks: true
+          script: |
+            const fs = require('fs');
+            const artifacts = await github.rest.actions.listWorkflowRunArtifacts({
+               owner: context.repo.owner,
+               repo: context.repo.repo,
+               run_id: ${{ github.event.workflow_run.id }},
+            });
+            const [matchArtifact] = artifacts.data.artifacts.filter((artifact) =>
+              artifact.name == "mypy_primer_diffs");
 
-      - name: Parse pull request number
-        id: pr-number
-        run: |
-          if [[ -f pr-number ]]
-          then
-            echo "pr-number=$(<pr-number)" >> "$GITHUB_OUTPUT"
-          fi
+            const download = await github.rest.actions.downloadArtifact({
+               owner: context.repo.owner,
+               repo: context.repo.repo,
+               artifact_id: matchArtifact.id,
+               archive_format: "zip",
+            });
+            fs.writeFileSync("diff.zip", Buffer.from(download.data));
 
-      - uses: dawidd6/action-download-artifact@20319c5641d495c8a52e688b7dc5fada6c3a9fbc # v8
-        name: "Download mypy_primer results"
-        id: download-mypy_primer_diff
-        if: steps.pr-number.outputs.pr-number
+      - run: unzip diff.zip
+      - run: |
+          cat mypy_primer_*.diff | tee fulldiff.txt
+
+      - name: Post comment
+        id: post-comment
+        uses: actions/github-script@v7
         with:
-          name: mypy_primer_diff
-          workflow: mypy_primer.yaml
-          pr: ${{ steps.pr-number.outputs.pr-number }}
-          path: pr/mypy_primer_diff
-          workflow_conclusion: completed
-          if_no_artifact_found: ignore
-          allow_forks: true
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const MAX_CHARACTERS = 50000
+            const MAX_CHARACTERS_PER_PROJECT = MAX_CHARACTERS / 3
 
-      - name: Generate comment content
-        id: generate-comment
-        if: steps.download-mypy_primer_diff.outputs.found_artifact == 'true'
-        run: |
-          # Guard against malicious mypy_primer results that symlink to a secret
-          # file on this runner
-          if [[ -L pr/mypy_primer_diff/mypy_primer.diff ]]
-          then
-              echo "Error: mypy_primer.diff cannot be a symlink"
-              exit 1
-          fi
+            const fs = require('fs')
+            let data = fs.readFileSync('fulldiff.txt', { encoding: 'utf8' })
 
-          # Note this identifier is used to find the comment to update on
-          # subsequent runs
-          echo '<!-- generated-comment mypy_primer -->' >> comment.txt
+            function truncateIfNeeded(original, maxLength) {
+              if (original.length <= maxLength) {
+                return original
+              }
+              let truncated = original.substring(0, maxLength)
+              // further, remove last line that might be truncated
+              truncated = truncated.substring(0, truncated.lastIndexOf('\n'))
+              let lines_truncated = original.split('\n').length - truncated.split('\n').length
+              return `${truncated}\n\n... (truncated ${lines_truncated} lines) ...`
+            }
 
-          echo '## `mypy_primer` results' >> comment.txt
-          if [ -s "pr/mypy_primer_diff/mypy_primer.diff" ]; then
-            echo '<details>' >> comment.txt
-            echo '<summary>Changes were detected when running on open source projects</summary>' >> comment.txt
-            echo '' >> comment.txt
-            echo '```diff' >> comment.txt
-            cat pr/mypy_primer_diff/mypy_primer.diff >> comment.txt
-            echo '```' >> comment.txt
-            echo '</details>' >> comment.txt
-          else
-            echo 'No ecosystem changes detected ✅' >> comment.txt
-          fi
+            const projects = data.split('\n\n')
+            // don't let one project dominate
+            data = projects.map(project => truncateIfNeeded(project, MAX_CHARACTERS_PER_PROJECT)).join('\n\n')
+            // posting comment fails if too long, so truncate
+            data = truncateIfNeeded(data, MAX_CHARACTERS)
 
-          echo 'comment<<EOF' >> "$GITHUB_OUTPUT"
-          cat comment.txt >> "$GITHUB_OUTPUT"
-          echo 'EOF' >> "$GITHUB_OUTPUT"
+            console.log("Diff from mypy_primer:")
+            console.log(data)
 
-      - name: Find existing comment
-        uses: peter-evans/find-comment@3eae4d37986fb5a8592848f6a574fdf654e61f9e # v3
-        if: steps.generate-comment.outcome == 'success'
-        id: find-comment
+            let body
+            if (data.trim()) {
+              body = 'Diff from [mypy_primer](https://github.com/hauntsaninja/mypy_primer), showing the effect of this PR on open source code:\n```diff\n' + data + '```'
+            } else {
+              body = "According to [mypy_primer](https://github.com/hauntsaninja/mypy_primer), this change doesn't affect type check results on a corpus of open source code. ✅"
+            }
+            const prNumber = parseInt(fs.readFileSync("pr-number", { encoding: "utf8" }))
+            await github.rest.issues.createComment({
+              issue_number: prNumber,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body
+            })
+            return prNumber
+
+      - name: Hide old comments
+        # v0.4.0
+        uses: kanga333/comment-hider@c12bb20b48aeb8fc098e35967de8d4f8018fffdf
         with:
-          issue-number: ${{ steps.pr-number.outputs.pr-number }}
-          comment-author: "github-actions[bot]"
-          body-includes: "<!-- generated-comment mypy_primer -->"
-
-      - name: Create or update comment
-        if: steps.find-comment.outcome == 'success'
-        uses: peter-evans/create-or-update-comment@71345be0265236311c031f5c7866368bd1eff043 # v4
-        with:
-          comment-id: ${{ steps.find-comment.outputs.comment-id }}
-          issue-number: ${{ steps.pr-number.outputs.pr-number }}
-          body-path: comment.txt
-          edit-mode: replace
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          leave_visible: 1
+          issue_number: ${{ steps.post-comment.outputs.result }}

.github/workflows/publish-pypi.yml

@@ -22,7 +22,7 @@ jobs:
       id-token: write
     steps:
       - name: "Install uv"
-        uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5.4.2
+        uses: astral-sh/setup-uv@0c5e2b8115b80b4c7c5ddf6ffdd634974642d182 # v5.4.1
       - uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e # v4.2.1
         with:
           pattern: wheels-*

.pre-commit-config.yaml

@@ -79,7 +79,7 @@ repos:
         pass_filenames: false # This makes it a lot faster
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.11.6
+    rev: v0.11.5
     hooks:
       - id: ruff-format
       - id: ruff
@@ -97,7 +97,7 @@ repos:
   # zizmor detects security vulnerabilities in GitHub Actions workflows.
   # Additional configuration for the tool is found in `.github/zizmor.yml`
   - repo: https://github.com/woodruffw/zizmor-pre-commit
-    rev: v1.6.0
+    rev: v1.5.2
     hooks:
       - id: zizmor
 

Cargo.lock

@@ -334,9 +334,9 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.37"
+version = "4.5.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eccb054f56cbd38340b380d4a8e69ef1f02f1af43db2f0cc817a4774d80ae071"
+checksum = "2df961d8c8a0d08aa9945718ccf584145eee3f3aa06cddbeac12933781102e04"
 dependencies = [
  "clap_builder",
  "clap_derive",
@@ -344,9 +344,9 @@ dependencies = [
 
 [[package]]
 name = "clap_builder"
-version = "4.5.37"
+version = "4.5.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "efd9466fac8543255d3b1fcad4762c5e116ffe808c8a3043d4263cd4fd4862a2"
+checksum = "132dbda40fb6753878316a489d5a1242a8ef2f0d9e47ba01c951ea8aa7d013a5"
 dependencies = [
  "anstream",
  "anstyle",
@@ -478,7 +478,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "117725a109d387c937a1533ce01b450cbde6b88abceea8473c4d7a85853cda3c"
 dependencies = [
  "lazy_static",
- "windows-sys 0.52.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -487,7 +487,7 @@ version = "3.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fde0e0ec90c9dfb3b4b1a0891a7dcd0e2bffde2f7efed5fe7c9bb00e5bfb915e"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]
@@ -918,7 +918,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "33d852cb9b869c2a9b3df2f71a3074817f01e1844f839a144f5fcef059a4eb5d"
 dependencies = [
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1499,7 +1499,7 @@ checksum = "e04d7f318608d35d4b61ddd75cbdaee86b023ebe2bd5a66ee0915f0bf93095a9"
 dependencies = [
  "hermit-abi 0.5.0",
  "libc",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -1553,9 +1553,9 @@ checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "jiff"
-version = "0.2.9"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59ec30f7142be6fe14e1b021f50b85db8df2d4324ea6e91ec3e5dcde092021d0"
+checksum = "d699bc6dfc879fb1bf9bdff0d4c56f0884fc6f0d0eb0fba397a6d00cd9a6b85e"
 dependencies = [
  "jiff-static",
  "jiff-tzdb-platform",
@@ -1563,14 +1563,14 @@ dependencies = [
  "portable-atomic",
  "portable-atomic-util",
  "serde",
- "windows-sys 0.59.0",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
 name = "jiff-static"
-version = "0.2.9"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "526b834d727fd59d37b076b0c3236d9adde1b1729a4361e20b2026f738cc1dbe"
+checksum = "8d16e75759ee0aa64c57a56acbf43916987b20c77373cb7e808979e02b93c9f9"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1645,9 +1645,9 @@ checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
 [[package]]
 name = "libc"
-version = "0.2.172"
+version = "0.2.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
+checksum = "c19937216e9d3aa9956d9bb8dfc0b0c8beb6058fc4f7a4dc4d850edf86a237d6"
 
 [[package]]
 name = "libcst"
@@ -2327,9 +2327,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.95"
+version = "1.0.94"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
+checksum = "a31971752e70b8b2686d7e46ec17fb38dad4051d94024c88df49b667caea9c84"
 dependencies = [
  "unicode-ident",
 ]
@@ -2420,12 +2420,13 @@ dependencies = [
 
 [[package]]
 name = "rand"
-version = "0.9.1"
+version = "0.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9fbfd9d094a40bf3ae768db9361049ace4c0e04a4fd6b359518bd7b73a73dd97"
+checksum = "3779b94aeb87e8bd4e834cee3650289ee9e0d5677f976ecdb6d219e5f4f6cd94"
 dependencies = [
  "rand_chacha 0.9.0",
  "rand_core 0.9.3",
+ "zerocopy",
 ]
 
 [[package]]
@@ -3083,7 +3084,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "itertools 0.14.0",
- "rand 0.9.1",
+ "rand 0.9.0",
  "ruff_diagnostics",
  "ruff_source_file",
  "ruff_text_size",
@@ -3427,7 +3428,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.4.15",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3440,7 +3441,7 @@ dependencies = [
  "errno",
  "libc",
  "linux-raw-sys 0.9.3",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -3674,9 +3675,9 @@ dependencies = [
 
 [[package]]
 name = "shellexpand"
-version = "3.1.1"
+version = "3.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8b1fdf65dd6331831494dd616b30351c38e96e45921a27745cf98490458b90bb"
+checksum = "da03fa3b94cc19e3ebfc88c4229c49d8f08cdbd1228870a45f0ffdf84988e14b"
 dependencies = [
  "dirs",
 ]
@@ -3826,7 +3827,7 @@ dependencies = [
  "getrandom 0.3.2",
  "once_cell",
  "rustix 1.0.2",
- "windows-sys 0.52.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -4327,7 +4328,7 @@ checksum = "458f7a779bf54acc9f347480ac654f68407d3aab21269a6e3c9f922acd9e2da9"
 dependencies = [
  "getrandom 0.3.2",
  "js-sys",
- "rand 0.9.1",
+ "rand 0.9.0",
  "uuid-macro-internal",
  "wasm-bindgen",
 ]
@@ -4598,7 +4599,7 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
 dependencies = [
- "windows-sys 0.52.0",
+ "windows-sys 0.48.0",
 ]
 
 [[package]]

crates/red_knot/src/main.rs

@@ -295,7 +295,7 @@ impl MainLoop {
 
                             writeln!(
                                 stdout,
-                                "Found {} diagnostic{}",
+                                "Founded {} diagnostic{}",
                                 diagnostics_count,
                                 if diagnostics_count > 1 { "s" } else { "" }
                             )?;

crates/red_knot/tests/cli.rs

@@ -28,7 +28,7 @@ fn config_override_python_version() -> anyhow::Result<()> {
         ),
     ])?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -40,10 +40,10 @@ fn config_override_python_version() -> anyhow::Result<()> {
       |       ^^^^^^^^^^^^ Type `<module 'sys'>` has no attribute `last_exc`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     assert_cmd_snapshot!(case.command().arg("--python-version").arg("3.12"), @r"
     success: true
@@ -79,7 +79,7 @@ fn config_override_python_platform() -> anyhow::Result<()> {
         ),
     ])?;
 
-    assert_cmd_snapshot!(case.command(), @r#"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -92,12 +92,12 @@ fn config_override_python_platform() -> anyhow::Result<()> {
       | ^^^^^^^^^^^^^^^^^^^^^^^^^ `Literal["linux"]`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    "#);
+    "###);
 
-    assert_cmd_snapshot!(case.command().arg("--python-platform").arg("all"), @r"
+    assert_cmd_snapshot!(case.command().arg("--python-platform").arg("all"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -110,10 +110,10 @@ fn config_override_python_platform() -> anyhow::Result<()> {
       | ^^^^^^^^^^^^^^^^^^^^^^^^^ `LiteralString`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -161,7 +161,7 @@ fn cli_arguments_are_relative_to_the_current_directory() -> anyhow::Result<()> {
     ])?;
 
     // Make sure that the CLI fails when the `libs` directory is not in the search path.
-    assert_cmd_snapshot!(case.command().current_dir(case.root().join("child")), @r"
+    assert_cmd_snapshot!(case.command().current_dir(case.root().join("child")), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -174,10 +174,10 @@ fn cli_arguments_are_relative_to_the_current_directory() -> anyhow::Result<()> {
     4 | stat = add(10, 15)
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     assert_cmd_snapshot!(case.command().current_dir(case.root().join("child")).arg("--extra-search-path").arg("../libs"), @r"
     success: true
@@ -261,7 +261,7 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
 
     // Assert that there's a possibly unresolved reference diagnostic
     // and that division-by-zero has a severity of error by default.
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -283,10 +283,10 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
       |       ^ Name `x` used when possibly not defined
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     case.write_file(
         "pyproject.toml",
@@ -297,7 +297,7 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
     "#,
     )?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -310,10 +310,10 @@ fn configuration_rule_severity() -> anyhow::Result<()> {
     4 | for a in range(0, int(y)):
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -337,7 +337,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
 
     // Assert that there's a possibly unresolved reference diagnostic
     // and that division-by-zero has a severity of error by default.
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -370,10 +370,10 @@ fn cli_rule_severity() -> anyhow::Result<()> {
       |       ^ Name `x` used when possibly not defined
       |
 
-    Found 3 diagnostics
+    Founded 3 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     assert_cmd_snapshot!(
         case
@@ -384,7 +384,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
             .arg("division-by-zero")
             .arg("--warn")
             .arg("unresolved-import"),
-        @r"
+        @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -408,10 +408,10 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     6 | for a in range(0, int(y)):
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    "
+    "###
     );
 
     Ok(())
@@ -435,7 +435,7 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
 
     // Assert that there's a possibly unresolved reference diagnostic
     // and that division-by-zero has a severity of error by default.
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -457,10 +457,10 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
       |       ^ Name `x` used when possibly not defined
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     assert_cmd_snapshot!(
         case
@@ -472,7 +472,7 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
             // Override the error severity with warning
             .arg("--ignore")
             .arg("possibly-unresolved-reference"),
-        @r"
+        @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -485,10 +485,10 @@ fn cli_rule_severity_precedence() -> anyhow::Result<()> {
     4 | for a in range(0, int(y)):
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    "
+    "###
     );
 
     Ok(())
@@ -508,7 +508,7 @@ fn configuration_unknown_rules() -> anyhow::Result<()> {
         ("test.py", "print(10)"),
     ])?;
 
-    assert_cmd_snapshot!(case.command(), @r#"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -520,10 +520,10 @@ fn configuration_unknown_rules() -> anyhow::Result<()> {
       | ^^^^^^^^^^^^^^^ Unknown lint rule `division-by-zer`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    "#);
+    "###);
 
     Ok(())
 }
@@ -533,16 +533,16 @@ fn configuration_unknown_rules() -> anyhow::Result<()> {
 fn cli_unknown_rules() -> anyhow::Result<()> {
     let case = TestCase::with_file("test.py", "print(10)")?;
 
-    assert_cmd_snapshot!(case.command().arg("--ignore").arg("division-by-zer"), @r"
+    assert_cmd_snapshot!(case.command().arg("--ignore").arg("division-by-zer"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     warning: unknown-rule: Unknown lint rule `division-by-zer`
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -551,7 +551,7 @@ fn cli_unknown_rules() -> anyhow::Result<()> {
 fn exit_code_only_warnings() -> anyhow::Result<()> {
     let case = TestCase::with_file("test.py", r"print(x)  # [unresolved-reference]")?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -562,10 +562,10 @@ fn exit_code_only_warnings() -> anyhow::Result<()> {
       |       ^ Name `x` used when not defined
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -580,7 +580,7 @@ fn exit_code_only_info() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -592,10 +592,10 @@ fn exit_code_only_info() -> anyhow::Result<()> {
       | ^^^^^^^^^^^^^^ `Literal[1]`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -610,7 +610,7 @@ fn exit_code_only_info_and_error_on_warning_is_true() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r"
+    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -622,10 +622,10 @@ fn exit_code_only_info_and_error_on_warning_is_true() -> anyhow::Result<()> {
       | ^^^^^^^^^^^^^^ `Literal[1]`
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -634,7 +634,7 @@ fn exit_code_only_info_and_error_on_warning_is_true() -> anyhow::Result<()> {
 fn exit_code_no_errors_but_error_on_warning_is_true() -> anyhow::Result<()> {
     let case = TestCase::with_file("test.py", r"print(x)  # [unresolved-reference]")?;
 
-    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r"
+    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -645,10 +645,10 @@ fn exit_code_no_errors_but_error_on_warning_is_true() -> anyhow::Result<()> {
       |       ^ Name `x` used when not defined
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -666,7 +666,7 @@ fn exit_code_no_errors_but_error_on_warning_is_enabled_in_configuration() -> any
         ),
     ])?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -677,10 +677,10 @@ fn exit_code_no_errors_but_error_on_warning_is_enabled_in_configuration() -> any
       |       ^ Name `x` used when not defined
       |
 
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -695,7 +695,7 @@ fn exit_code_both_warnings_and_errors() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command(), @r"
+    assert_cmd_snapshot!(case.command(), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -715,10 +715,10 @@ fn exit_code_both_warnings_and_errors() -> anyhow::Result<()> {
       |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -733,7 +733,7 @@ fn exit_code_both_warnings_and_errors_and_error_on_warning_is_true() -> anyhow::
         "###,
     )?;
 
-    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r"
+    assert_cmd_snapshot!(case.command().arg("--error-on-warning"), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -753,10 +753,10 @@ fn exit_code_both_warnings_and_errors_and_error_on_warning_is_true() -> anyhow::
       |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -771,7 +771,7 @@ fn exit_code_exit_zero_is_true() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command().arg("--exit-zero"), @r"
+    assert_cmd_snapshot!(case.command().arg("--exit-zero"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -791,10 +791,10 @@ fn exit_code_exit_zero_is_true() -> anyhow::Result<()> {
       |       ^ Cannot subscript object of type `Literal[4]` with no `__getitem__` method
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -831,7 +831,7 @@ fn user_configuration() -> anyhow::Result<()> {
 
     assert_cmd_snapshot!(
         case.command().current_dir(case.root().join("project")).env(config_env_var, config_directory.as_os_str()),
-        @r"
+        @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -853,10 +853,10 @@ fn user_configuration() -> anyhow::Result<()> {
       |       ^ Name `x` used when possibly not defined
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    "
+    "###
     );
 
     // The user-level configuration promotes `possibly-unresolved-reference` to an error.
@@ -873,7 +873,7 @@ fn user_configuration() -> anyhow::Result<()> {
 
     assert_cmd_snapshot!(
         case.command().current_dir(case.root().join("project")).env(config_env_var, config_directory.as_os_str()),
-        @r"
+        @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -895,10 +895,10 @@ fn user_configuration() -> anyhow::Result<()> {
       |       ^ Name `x` used when possibly not defined
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    "
+    "###
     );
 
     Ok(())
@@ -931,7 +931,7 @@ fn check_specific_paths() -> anyhow::Result<()> {
 
     assert_cmd_snapshot!(
         case.command(),
-        @r"
+        @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -958,17 +958,17 @@ fn check_specific_paths() -> anyhow::Result<()> {
     4 | print(z)
       |
 
-    Found 3 diagnostics
+    Founded 3 diagnostics
 
     ----- stderr -----
-    "
+    "###
     );
 
     // Now check only the `tests` and `other.py` files.
     // We should no longer see any diagnostics related to `main.py`.
     assert_cmd_snapshot!(
         case.command().arg("project/tests").arg("project/other.py"),
-        @r"
+        @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -988,10 +988,10 @@ fn check_specific_paths() -> anyhow::Result<()> {
     4 | print(z)
       |
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    "
+    "###
     );
 
     Ok(())
@@ -1010,7 +1010,7 @@ fn check_non_existing_path() -> anyhow::Result<()> {
 
     assert_cmd_snapshot!(
         case.command().arg("project/main.py").arg("project/tests"),
-        @r"
+        @r###"
     success: false
     exit_code: 1
     ----- stdout -----
@@ -1018,11 +1018,11 @@ fn check_non_existing_path() -> anyhow::Result<()> {
 
     error: io: `<temp_dir>/project/tests`: No such file or directory (os error 2)
 
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
     WARN No python files found under the given path(s)
-    "
+    "###
     );
 
     Ok(())
@@ -1038,16 +1038,16 @@ fn concise_diagnostics() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command().arg("--output-format=concise"), @r"
+    assert_cmd_snapshot!(case.command().arg("--output-format=concise"), @r###"
     success: false
     exit_code: 1
     ----- stdout -----
     warning[lint:unresolved-reference] <temp_dir>/test.py:2:7: Name `x` used when not defined
     error[lint:non-subscriptable] <temp_dir>/test.py:3:7: Cannot subscript object of type `Literal[4]` with no `__getitem__` method
-    Found 2 diagnostics
+    Founded 2 diagnostics
 
     ----- stderr -----
-    ");
+    "###);
 
     Ok(())
 }
@@ -1072,15 +1072,15 @@ fn concise_revealed_type() -> anyhow::Result<()> {
         "#,
     )?;
 
-    assert_cmd_snapshot!(case.command().arg("--output-format=concise"), @r#"
+    assert_cmd_snapshot!(case.command().arg("--output-format=concise"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
     info[revealed-type] <temp_dir>/test.py:5:1: Revealed type: `Literal["hello"]`
-    Found 1 diagnostic
+    Founded 1 diagnostic
 
     ----- stderr -----
-    "#);
+    "###);
 
     Ok(())
 }

crates/red_knot_project/tests/check.rs

@@ -6,9 +6,7 @@ use ruff_db::parsed::parsed_module;
 use ruff_db::system::{SystemPath, SystemPathBuf, TestSystem};
 use ruff_python_ast::visitor::source_order;
 use ruff_python_ast::visitor::source_order::SourceOrderVisitor;
-use ruff_python_ast::{
-    self as ast, Alias, Comprehension, Expr, Parameter, ParameterWithDefault, Stmt,
-};
+use ruff_python_ast::{self as ast, Alias, Expr, Parameter, ParameterWithDefault, Stmt};
 
 fn setup_db(project_root: &SystemPath, system: TestSystem) -> anyhow::Result<ProjectDatabase> {
     let project = ProjectMetadata::discover(project_root, &system)?;
@@ -260,14 +258,6 @@ impl SourceOrderVisitor<'_> for PullTypesVisitor<'_> {
         source_order::walk_expr(self, expr);
     }
 
-    fn visit_comprehension(&mut self, comprehension: &Comprehension) {
-        self.visit_expr(&comprehension.iter);
-        self.visit_target(&comprehension.target);
-        for if_expr in &comprehension.ifs {
-            self.visit_expr(if_expr);
-        }
-    }
-
     fn visit_parameter(&mut self, parameter: &Parameter) {
         let _ty = parameter.inferred_type(&self.model);
 

crates/red_knot_python_semantic/resources/mdtest/attributes.md

@@ -397,27 +397,15 @@ class IntIterable:
     def __iter__(self) -> IntIterator:
         return IntIterator()
 
-class TupleIterator:
-    def __next__(self) -> tuple[int, str]:
-        return (1, "a")
-
-class TupleIterable:
-    def __iter__(self) -> TupleIterator:
-        return TupleIterator()
-
 class C:
     def __init__(self) -> None:
         [... for self.a in IntIterable()]
-        [... for (self.b, self.c) in TupleIterable()]
-        [... for self.d in IntIterable() for self.e in IntIterable()]
 
 c_instance = C()
 
-reveal_type(c_instance.a)  # revealed: Unknown | int
-reveal_type(c_instance.b)  # revealed: Unknown | int
-reveal_type(c_instance.c)  # revealed: Unknown | str
-reveal_type(c_instance.d)  # revealed: Unknown | int
-reveal_type(c_instance.e)  # revealed: Unknown | int
+# TODO: Should be `Unknown | int`
+# error: [unresolved-attribute]
+reveal_type(c_instance.a)  # revealed: Unknown
 ```
 
 #### Conditionally declared / bound attributes

crates/red_knot_python_semantic/resources/mdtest/function/return_type.md

@@ -74,6 +74,8 @@ class Baz(Bar):
 T = TypeVar("T")
 
 class Qux(Protocol[T]):
+    # TODO: no error
+    # error: [invalid-return-type]
     def f(self) -> int: ...
 
 class Foo(Protocol):

crates/red_knot_python_semantic/resources/mdtest/protocols.md

@@ -40,63 +40,27 @@ class Foo(Protocol, Protocol): ...  # error: [inconsistent-mro]
 reveal_type(Foo.__mro__)  # revealed: tuple[Literal[Foo], Unknown, Literal[object]]
 ```
 
-Protocols can also be generic, either by including `Generic[]` in the bases list, subscripting
-`Protocol` directly in the bases list, using PEP-695 type parameters, or some combination of the
-above:
-
-```py
-from typing import TypeVar, Generic
-
-T = TypeVar("T")
-
-class Bar0(Protocol[T]):
-    x: T
-
-class Bar1(Protocol[T], Generic[T]):
-    x: T
-
-class Bar2[T](Protocol):
-    x: T
-
-class Bar3[T](Protocol[T]):
-    x: T
-```
-
-It's an error to include both bare `Protocol` and subscripted `Protocol[]` in the bases list
-simultaneously:
-
-```py
-# TODO: should emit a `[duplicate-bases]` error here:
-class DuplicateBases(Protocol, Protocol[T]):
-    x: T
-
-# TODO: should not have `Generic` multiple times and `Protocol` multiple times
-# revealed: tuple[Literal[DuplicateBases], typing.Protocol, typing.Generic, @Todo(`Protocol[]` subscript), @Todo(`Generic[]` subscript), Literal[object]]
-reveal_type(DuplicateBases.__mro__)
-```
-
 The introspection helper `typing(_extensions).is_protocol` can be used to verify whether a class is
 a protocol class or not:
 
 ```py
 from typing_extensions import is_protocol
 
-reveal_type(is_protocol(MyProtocol))  # revealed: Literal[True]
-reveal_type(is_protocol(Bar0))  # revealed: Literal[True]
-reveal_type(is_protocol(Bar1))  # revealed: Literal[True]
-reveal_type(is_protocol(Bar2))  # revealed: Literal[True]
-reveal_type(is_protocol(Bar3))  # revealed: Literal[True]
+# TODO: should be `Literal[True]`
+reveal_type(is_protocol(MyProtocol))  # revealed: bool
 
 class NotAProtocol: ...
 
-reveal_type(is_protocol(NotAProtocol))  # revealed: Literal[False]
+# TODO: should be `Literal[False]`
+reveal_type(is_protocol(NotAProtocol))  # revealed: bool
 ```
 
 A type checker should follow the typeshed stubs if a non-class is passed in, and typeshed's stubs
-indicate that the argument passed in must be an instance of `type`.
+indicate that the argument passed in must be an instance of `type`. `Literal[False]` should be
+inferred as the return type, however.
 
 ```py
-# We could also reasonably infer `Literal[False]` here, but it probably doesn't matter that much:
+# TODO: the diagnostic is correct, but should infer `Literal[False]`
 # error: [invalid-argument-type]
 reveal_type(is_protocol("not a class"))  # revealed: bool
 ```
@@ -110,7 +74,8 @@ class SubclassOfMyProtocol(MyProtocol): ...
 # revealed: tuple[Literal[SubclassOfMyProtocol], Literal[MyProtocol], typing.Protocol, typing.Generic, Literal[object]]
 reveal_type(SubclassOfMyProtocol.__mro__)
 
-reveal_type(is_protocol(SubclassOfMyProtocol))  # revealed: Literal[False]
+# TODO: should be `Literal[False]`
+reveal_type(is_protocol(SubclassOfMyProtocol))  # revealed: bool
 ```
 
 A protocol class may inherit from other protocols, however, as long as it re-inherits from
@@ -119,7 +84,8 @@ A protocol class may inherit from other protocols, however, as long as it re-inh
 ```py
 class SubProtocol(MyProtocol, Protocol): ...
 
-reveal_type(is_protocol(SubProtocol))  # revealed: Literal[True]
+# TODO: should be `Literal[True]`
+reveal_type(is_protocol(SubProtocol))  # revealed: bool
 
 class OtherProtocol(Protocol):
     some_attribute: str
@@ -129,20 +95,21 @@ class ComplexInheritance(SubProtocol, OtherProtocol, Protocol): ...
 # revealed: tuple[Literal[ComplexInheritance], Literal[SubProtocol], Literal[MyProtocol], Literal[OtherProtocol], typing.Protocol, typing.Generic, Literal[object]]
 reveal_type(ComplexInheritance.__mro__)
 
-reveal_type(is_protocol(ComplexInheritance))  # revealed: Literal[True]
+# TODO: should be `Literal[True]`
+reveal_type(is_protocol(ComplexInheritance))  # revealed: bool
 ```
 
 If `Protocol` is present in the bases tuple, all other bases in the tuple must be protocol classes,
 or `TypeError` is raised at runtime when the class is created.
 
 ```py
-# error: [invalid-protocol] "Protocol class `Invalid` cannot inherit from non-protocol class `NotAProtocol`"
+# TODO: should emit `[invalid-protocol]`
 class Invalid(NotAProtocol, Protocol): ...
 
 # revealed: tuple[Literal[Invalid], Literal[NotAProtocol], typing.Protocol, typing.Generic, Literal[object]]
 reveal_type(Invalid.__mro__)
 
-# error: [invalid-protocol] "Protocol class `AlsoInvalid` cannot inherit from non-protocol class `NotAProtocol`"
+# TODO: should emit an `[invalid-protocol`] error
 class AlsoInvalid(MyProtocol, OtherProtocol, NotAProtocol, Protocol): ...
 
 # revealed: tuple[Literal[AlsoInvalid], Literal[MyProtocol], Literal[OtherProtocol], Literal[NotAProtocol], typing.Protocol, typing.Generic, Literal[object]]
@@ -167,8 +134,6 @@ reveal_type(Fine.__mro__)  # revealed: tuple[Literal[Fine], typing.Protocol, typ
 
 class StillFine(Protocol, Generic[T], object): ...
 class EvenThis[T](Protocol, object): ...
-class OrThis(Protocol[T], Generic[T]): ...
-class AndThis(Protocol[T], Generic[T], object): ...
 ```
 
 And multiple inheritance from a mix of protocol and non-protocol classes is fine as long as
@@ -185,7 +150,8 @@ But if `Protocol` is not present in the bases list, the resulting class doesn't
 class anymore:
 
 ```py
-reveal_type(is_protocol(FineAndDandy))  # revealed: Literal[False]
+# TODO: should reveal `Literal[False]`
+reveal_type(is_protocol(FineAndDandy))  # revealed: bool
 ```
 
 A class does not *have* to inherit from a protocol class in order for it to be considered a subtype
@@ -264,10 +230,9 @@ class Foo(typing.Protocol):
 class Bar(typing_extensions.Protocol):
     x: int
 
-static_assert(typing_extensions.is_protocol(Foo))
-static_assert(typing_extensions.is_protocol(Bar))
-
-# TODO: should pass
+# TODO: these should pass
+static_assert(typing_extensions.is_protocol(Foo))  # error: [static-assert-error]
+static_assert(typing_extensions.is_protocol(Bar))  # error: [static-assert-error]
 static_assert(is_equivalent_to(Foo, Bar))  # error: [static-assert-error]
 ```
 
@@ -282,10 +247,9 @@ class RuntimeCheckableFoo(typing.Protocol):
 class RuntimeCheckableBar(typing_extensions.Protocol):
     x: int
 
-static_assert(typing_extensions.is_protocol(RuntimeCheckableFoo))
-static_assert(typing_extensions.is_protocol(RuntimeCheckableBar))
-
-# TODO: should pass
+# TODO: these should pass
+static_assert(typing_extensions.is_protocol(RuntimeCheckableFoo))  # error: [static-assert-error]
+static_assert(typing_extensions.is_protocol(RuntimeCheckableBar))  # error: [static-assert-error]
 static_assert(is_equivalent_to(RuntimeCheckableFoo, RuntimeCheckableBar))  # error: [static-assert-error]
 
 # These should not error because the protocols are decorated with `@runtime_checkable`

crates/red_knot_python_semantic/resources/mdtest/unpacking.md

@@ -708,95 +708,3 @@ with ContextManager() as (a, b, c):
     reveal_type(b)  # revealed: Unknown
     reveal_type(c)  # revealed: Unknown
 ```
-
-## Comprehension
-
-Unpacking in a comprehension.
-
-### Same types
-
-```py
-def _(arg: tuple[tuple[int, int], tuple[int, int]]):
-    # revealed: tuple[int, int]
-    [reveal_type((a, b)) for a, b in arg]
-```
-
-### Mixed types (1)
-
-```py
-def _(arg: tuple[tuple[int, int], tuple[int, str]]):
-    # revealed: tuple[int, int | str]
-    [reveal_type((a, b)) for a, b in arg]
-```
-
-### Mixed types (2)
-
-```py
-def _(arg: tuple[tuple[int, str], tuple[str, int]]):
-    # revealed: tuple[int | str, str | int]
-    [reveal_type((a, b)) for a, b in arg]
-```
-
-### Mixed types (3)
-
-```py
-def _(arg: tuple[tuple[int, int, int], tuple[int, str, bytes], tuple[int, int, str]]):
-    # revealed: tuple[int, int | str, int | bytes | str]
-    [reveal_type((a, b, c)) for a, b, c in arg]
-```
-
-### Same literal values
-
-```py
-# revealed: tuple[Literal[1, 3], Literal[2, 4]]
-[reveal_type((a, b)) for a, b in ((1, 2), (3, 4))]
-```
-
-### Mixed literal values (1)
-
-```py
-# revealed: tuple[Literal[1, "a"], Literal[2, "b"]]
-[reveal_type((a, b)) for a, b in ((1, 2), ("a", "b"))]
-```
-
-### Mixed literals values (2)
-
-```py
-# error: "Object of type `Literal[1]` is not iterable"
-# error: "Object of type `Literal[2]` is not iterable"
-# error: "Object of type `Literal[4]` is not iterable"
-# error: [invalid-assignment] "Not enough values to unpack (expected 2, got 1)"
-# revealed: tuple[Unknown | Literal[3, 5], Unknown | Literal["a", "b"]]
-[reveal_type((a, b)) for a, b in (1, 2, (3, "a"), 4, (5, "b"), "c")]
-```
-
-### Custom iterator (1)
-
-```py
-class Iterator:
-    def __next__(self) -> tuple[int, int]:
-        return (1, 2)
-
-class Iterable:
-    def __iter__(self) -> Iterator:
-        return Iterator()
-
-# revealed: tuple[int, int]
-[reveal_type((a, b)) for a, b in Iterable()]
-```
-
-### Custom iterator (2)
-
-```py
-class Iterator:
-    def __next__(self) -> bytes:
-        return b""
-
-class Iterable:
-    def __iter__(self) -> Iterator:
-        return Iterator()
-
-def _(arg: tuple[tuple[int, str], Iterable]):
-    # revealed: tuple[int | bytes, str | bytes]
-    [reveal_type((a, b)) for a, b in arg]
-```

crates/red_knot_python_semantic/resources/primer/bad.txt

@@ -0,0 +1,32 @@
+Tanjun  # hangs?
+aiohttp  # missing expression ID
+alerta  # missing expression ID
+altair  # cycle panics (try_metaclass_)
+antidote  # hangs / slow
+artigraph  # cycle panics (value_type_)
+cpython  # missing expression ID, access to field whilst being initialized, too many cycle iterations
+colour  # cycle panics (try_metaclass_)
+core  # cycle panics (value_type_)
+dragonchain  # too many cycle iterations (member_lookup_with_policy)
+manticore  # stack overflow
+materialize  # stack overflow
+meson  # missing expression ID
+mypy  # cycle panic (signature_)
+pandas  # too many cycle iterations (member_lookup_with_policy)
+pandas-stubs  # cycle panics (try_metaclass)
+pip  # too many cycle iterations (infer_expression_types)
+poetry  # too many cycle iterations (member_lookup_with_policy, infer_expression_type)
+prefect # slow
+pytest  # cycle panics (signature_), missing expression ID
+pywin32  # bad use-def map (binding with definitely-visible unbound)
+schemathesis  # cycle panics (signature_)
+scikit-learn  # success, but mypy-primer hangs processing the output
+scipy  # missing expression ID
+setuptools  # too many cycle iterations (infer_definition_types)
+spack  # success, but mypy-primer hangs processing the output
+spark  # missing expression ID
+sphinx  # missing expression ID
+steam.py  # missing expression ID
+streamlit  # cycle panic (signature)
+sympy  # stack overflow
+trio  # missing expression ID

crates/red_knot_python_semantic/resources/primer/good.txt

@@ -1,23 +1,111 @@
+AutoSplit
+Expression
+PyGithub
+PyWinCtl
+SinbadCogs
+aiohttp-devtools
+aioredis
+aiortc
+alectryon
+anyio
+apprise
 arrow
+arviz
 async-utils
+asynq
+attrs
+bandersnatch
+beartype
 bidict
 black
+bokeh
+boostedblob
+check-jsonschema
+cki-lib
+cloud-init
+com2ann
+comtypes
+cwltool
 dacite
+dd-trace-py
+dedupe
+django-stubs
+downforeveryone
+dulwich
+flake8
+flake8-pyi
+freqtrade
 git-revise
+graphql-core
+httpx-caching
+hydpy
+hydra-zen
+ibis
+ignite
+imagehash
 isort
 itsdangerous
+janus
+jax
+jinja
+koda-validate
+kopf
+kornia
+mitmproxy
+mkdocs
+mkosi
+mongo-python-driver
+more-itertools
+mypy-protobuf
 mypy_primer
+nionutils
+nox
+openlibrary
+operator
+optuna
+paasta
 packaging
+pandera
 paroxython
+parso
+pegen
 porcupine
+ppb-vector
 psycopg
+pwndbg
 pybind11
+pycryptodome
+pydantic
 pyinstrument
+pyjwt
+pylint
+pylox
+pyodide
 pyp
+pyppeteer
+pytest-robotframework
 python-chess
 python-htmlgen
+python-sop
+rclip
 rich
+rotki
+schema_salad
 scrapy
+sockeye
+speedrun.com_global_scoreboard_webapp
+starlette
+static-frame
+stone
+tornado
+twine
 typeshed-stats
+urllib3
+vision
+websockets
 werkzeug
+xarray
+xarray-dataclasses
+yarl
 zipp
+zulip

crates/red_knot_python_semantic/src/semantic_index.rs

@@ -940,7 +940,7 @@ def f(a: str, /, b: str, c: int = 1, *args, d: int = 2, **kwargs):
             panic!("expected generator definition")
         };
         let target = comprehension.target();
-        let name = target.as_name_expr().unwrap().id().as_str();
+        let name = target.id().as_str();
 
         assert_eq!(name, "x");
         assert_eq!(target.range(), TextRange::new(23.into(), 24.into()));

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -18,12 +18,11 @@ use crate::semantic_index::ast_ids::node_key::ExpressionNodeKey;
 use crate::semantic_index::ast_ids::AstIdsBuilder;
 use crate::semantic_index::definition::{
     AnnotatedAssignmentDefinitionKind, AnnotatedAssignmentDefinitionNodeRef,
-    AssignmentDefinitionKind, AssignmentDefinitionNodeRef, ComprehensionDefinitionKind,
-    ComprehensionDefinitionNodeRef, Definition, DefinitionCategory, DefinitionKind,
-    DefinitionNodeKey, DefinitionNodeRef, Definitions, ExceptHandlerDefinitionNodeRef,
-    ForStmtDefinitionKind, ForStmtDefinitionNodeRef, ImportDefinitionNodeRef,
-    ImportFromDefinitionNodeRef, MatchPatternDefinitionNodeRef, StarImportDefinitionNodeRef,
-    TargetKind, WithItemDefinitionKind, WithItemDefinitionNodeRef,
+    AssignmentDefinitionKind, AssignmentDefinitionNodeRef, ComprehensionDefinitionNodeRef,
+    Definition, DefinitionCategory, DefinitionKind, DefinitionNodeKey, DefinitionNodeRef,
+    Definitions, ExceptHandlerDefinitionNodeRef, ForStmtDefinitionKind, ForStmtDefinitionNodeRef,
+    ImportDefinitionNodeRef, ImportFromDefinitionNodeRef, MatchPatternDefinitionNodeRef,
+    StarImportDefinitionNodeRef, TargetKind, WithItemDefinitionKind, WithItemDefinitionNodeRef,
 };
 use crate::semantic_index::expression::{Expression, ExpressionKind};
 use crate::semantic_index::predicate::{
@@ -355,14 +354,15 @@ impl<'db> SemanticIndexBuilder<'db> {
         self.current_use_def_map_mut().merge(state);
     }
 
-    /// Add a symbol to the symbol table and the use-def map.
-    /// Return the [`ScopedSymbolId`] that uniquely identifies the symbol in both.
-    fn add_symbol(&mut self, name: Name) -> ScopedSymbolId {
+    /// Return a 2-element tuple, where the first element is the [`ScopedSymbolId`] of the
+    /// symbol added, and the second element is a boolean indicating whether the symbol was *newly*
+    /// added or not
+    fn add_symbol(&mut self, name: Name) -> (ScopedSymbolId, bool) {
         let (symbol_id, added) = self.current_symbol_table().add_symbol(name);
         if added {
             self.current_use_def_map_mut().add_symbol(symbol_id);
         }
-        symbol_id
+        (symbol_id, added)
     }
 
     fn add_attribute(&mut self, name: Name) -> ScopedSymbolId {
@@ -796,7 +796,7 @@ impl<'db> SemanticIndexBuilder<'db> {
                         ..
                     }) => (name, &None, default),
                 };
-                let symbol = self.add_symbol(name.id.clone());
+                let (symbol, _) = self.add_symbol(name.id.clone());
                 // TODO create Definition for PEP 695 typevars
                 // note that the "bound" on the typevar is a totally different thing than whether
                 // or not a name is "bound" by a typevar declaration; the latter is always true.
@@ -850,35 +850,31 @@ impl<'db> SemanticIndexBuilder<'db> {
 
         // The `iter` of the first generator is evaluated in the outer scope, while all subsequent
         // nodes are evaluated in the inner scope.
-        let value = self.add_standalone_expression(&generator.iter);
+        self.add_standalone_expression(&generator.iter);
         self.visit_expr(&generator.iter);
         self.push_scope(scope);
 
-        self.add_unpackable_assignment(
-            &Unpackable::Comprehension {
-                node: generator,
-                first: true,
-            },
-            &generator.target,
-            value,
-        );
+        self.push_assignment(CurrentAssignment::Comprehension {
+            node: generator,
+            first: true,
+        });
+        self.visit_expr(&generator.target);
+        self.pop_assignment();
 
         for expr in &generator.ifs {
             self.visit_expr(expr);
         }
 
         for generator in generators_iter {
-            let value = self.add_standalone_expression(&generator.iter);
+            self.add_standalone_expression(&generator.iter);
             self.visit_expr(&generator.iter);
 
-            self.add_unpackable_assignment(
-                &Unpackable::Comprehension {
-                    node: generator,
-                    first: false,
-                },
-                &generator.target,
-                value,
-            );
+            self.push_assignment(CurrentAssignment::Comprehension {
+                node: generator,
+                first: false,
+            });
+            self.visit_expr(&generator.target);
+            self.pop_assignment();
 
             for expr in &generator.ifs {
                 self.visit_expr(expr);
@@ -894,20 +890,20 @@ impl<'db> SemanticIndexBuilder<'db> {
             self.declare_parameter(parameter);
         }
         if let Some(vararg) = parameters.vararg.as_ref() {
-            let symbol = self.add_symbol(vararg.name.id().clone());
+            let (symbol, _) = self.add_symbol(vararg.name.id().clone());
             self.add_definition(
                 symbol,
                 DefinitionNodeRef::VariadicPositionalParameter(vararg),
             );
         }
         if let Some(kwarg) = parameters.kwarg.as_ref() {
-            let symbol = self.add_symbol(kwarg.name.id().clone());
+            let (symbol, _) = self.add_symbol(kwarg.name.id().clone());
             self.add_definition(symbol, DefinitionNodeRef::VariadicKeywordParameter(kwarg));
         }
     }
 
     fn declare_parameter(&mut self, parameter: &'db ast::ParameterWithDefault) {
-        let symbol = self.add_symbol(parameter.name().id().clone());
+        let (symbol, _) = self.add_symbol(parameter.name().id().clone());
 
         let definition = self.add_definition(symbol, parameter);
 
@@ -937,30 +933,9 @@ impl<'db> SemanticIndexBuilder<'db> {
 
         let current_assignment = match target {
             ast::Expr::List(_) | ast::Expr::Tuple(_) => {
-                if matches!(unpackable, Unpackable::Comprehension { .. }) {
-                    debug_assert_eq!(
-                        self.scopes[self.current_scope()].node().scope_kind(),
-                        ScopeKind::Comprehension
-                    );
-                }
-                // The first iterator of the comprehension is evaluated in the outer scope, while all subsequent
-                // nodes are evaluated in the inner scope.
-                // SAFETY: The current scope is the comprehension, and the comprehension scope must have a parent scope.
-                let value_file_scope =
-                    if let Unpackable::Comprehension { first: true, .. } = unpackable {
-                        self.scope_stack
-                            .iter()
-                            .rev()
-                            .nth(1)
-                            .expect("The comprehension scope must have a parent scope")
-                            .file_scope_id
-                    } else {
-                        self.current_scope()
-                    };
                 let unpack = Some(Unpack::new(
                     self.db,
                     self.file,
-                    value_file_scope,
                     self.current_scope(),
                     // SAFETY: `target` belongs to the `self.module` tree
                     #[allow(unsafe_code)]
@@ -1138,7 +1113,7 @@ where
                 // The symbol for the function name itself has to be evaluated
                 // at the end to match the runtime evaluation of parameter defaults
                 // and return-type annotations.
-                let symbol = self.add_symbol(name.id.clone());
+                let (symbol, _) = self.add_symbol(name.id.clone());
 
                 // Record a use of the function name in the scope that it is defined in, so that it
                 // can be used to find previously defined functions with the same name. This is
@@ -1173,11 +1148,11 @@ where
                 );
 
                 // In Python runtime semantics, a class is registered after its scope is evaluated.
-                let symbol = self.add_symbol(class.name.id.clone());
+                let (symbol, _) = self.add_symbol(class.name.id.clone());
                 self.add_definition(symbol, class);
             }
             ast::Stmt::TypeAlias(type_alias) => {
-                let symbol = self.add_symbol(
+                let (symbol, _) = self.add_symbol(
                     type_alias
                         .name
                         .as_name_expr()
@@ -1214,7 +1189,7 @@ where
                         (Name::new(alias.name.id.split('.').next().unwrap()), false)
                     };
 
-                    let symbol = self.add_symbol(symbol_name);
+                    let (symbol, _) = self.add_symbol(symbol_name);
                     self.add_definition(
                         symbol,
                         ImportDefinitionNodeRef {
@@ -1285,7 +1260,7 @@ where
                         //
                         // For more details, see the doc-comment on `StarImportPlaceholderPredicate`.
                         for export in exported_names(self.db, referenced_module) {
-                            let symbol_id = self.add_symbol(export.clone());
+                            let (symbol_id, newly_added) = self.add_symbol(export.clone());
                             let node_ref = StarImportDefinitionNodeRef { node, symbol_id };
                             let star_import = StarImportPlaceholderPredicate::new(
                                 self.db,
@@ -1294,15 +1269,28 @@ where
                                 referenced_module,
                             );
 
-                            let pre_definition =
-                                self.current_use_def_map().single_symbol_snapshot(symbol_id);
-                            self.push_additional_definition(symbol_id, node_ref);
-                            self.current_use_def_map_mut()
-                                .record_and_negate_star_import_visibility_constraint(
-                                    star_import,
-                                    symbol_id,
-                                    pre_definition,
-                                );
+                            // Fast path for if there were no previous definitions
+                            // of the symbol defined through the `*` import:
+                            // we can apply the visibility constraint to *only* the added definition,
+                            // rather than all definitions
+                            if newly_added {
+                                self.push_additional_definition(symbol_id, node_ref);
+                                self.current_use_def_map_mut()
+                                    .record_and_negate_star_import_visibility_constraint(
+                                        star_import,
+                                        symbol_id,
+                                    );
+                            } else {
+                                let pre_definition = self.flow_snapshot();
+                                self.push_additional_definition(symbol_id, node_ref);
+                                let constraint_id =
+                                    self.record_visibility_constraint(star_import.into());
+                                let post_definition = self.flow_snapshot();
+                                self.flow_restore(pre_definition.clone());
+                                self.record_negated_visibility_constraint(constraint_id);
+                                self.flow_merge(post_definition);
+                                self.simplify_visibility_constraints(pre_definition);
+                            }
                         }
 
                         continue;
@@ -1322,7 +1310,7 @@ where
                     self.has_future_annotations |= alias.name.id == "annotations"
                         && node.module.as_deref() == Some("__future__");
 
-                    let symbol = self.add_symbol(symbol_name.clone());
+                    let (symbol, _) = self.add_symbol(symbol_name.clone());
 
                     self.add_definition(
                         symbol,
@@ -1740,7 +1728,7 @@ where
                         // which is invalid syntax. However, it's still pretty obvious here that the user
                         // *wanted* `e` to be bound, so we should still create a definition here nonetheless.
                         if let Some(symbol_name) = symbol_name {
-                            let symbol = self.add_symbol(symbol_name.id.clone());
+                            let (symbol, _) = self.add_symbol(symbol_name.id.clone());
 
                             self.add_definition(
                                 symbol,
@@ -1816,7 +1804,7 @@ where
         let node_key = NodeKey::from_node(expr);
 
         match expr {
-            ast::Expr::Name(ast::ExprName { id, ctx, .. }) => {
+            ast::Expr::Name(name_node @ ast::ExprName { id, ctx, .. }) => {
                 let (is_use, is_definition) = match (ctx, self.current_assignment()) {
                     (ast::ExprContext::Store, Some(CurrentAssignment::AugAssign(_))) => {
                         // For augmented assignment, the target expression is also used.
@@ -1827,7 +1815,7 @@ where
                     (ast::ExprContext::Del, _) => (false, true),
                     (ast::ExprContext::Invalid, _) => (false, false),
                 };
-                let symbol = self.add_symbol(id.clone());
+                let (symbol, _) = self.add_symbol(id.clone());
 
                 if is_use {
                     self.mark_symbol_used(symbol);
@@ -1879,17 +1867,12 @@ where
                             // implemented.
                             self.add_definition(symbol, named);
                         }
-                        Some(CurrentAssignment::Comprehension {
-                            unpack,
-                            node,
-                            first,
-                        }) => {
+                        Some(CurrentAssignment::Comprehension { node, first }) => {
                             self.add_definition(
                                 symbol,
                                 ComprehensionDefinitionNodeRef {
-                                    unpack,
                                     iterable: &node.iter,
-                                    target: expr,
+                                    target: name_node,
                                     first,
                                     is_async: node.is_async,
                                 },
@@ -2160,37 +2143,14 @@ where
                                 DefinitionKind::WithItem(assignment),
                             );
                         }
-                        Some(CurrentAssignment::Comprehension {
-                            unpack,
-                            node,
-                            first,
-                        }) => {
-                            // SAFETY: `iter` and `expr` belong to the `self.module` tree
-                            #[allow(unsafe_code)]
-                            let assignment = ComprehensionDefinitionKind {
-                                target_kind: TargetKind::from(unpack),
-                                iterable: unsafe {
-                                    AstNodeRef::new(self.module.clone(), &node.iter)
-                                },
-                                target: unsafe { AstNodeRef::new(self.module.clone(), expr) },
-                                first,
-                                is_async: node.is_async,
-                            };
-                            // Temporarily move to the scope of the method to which the instance attribute is defined.
-                            // SAFETY: `self.scope_stack` is not empty because the targets in comprehensions should always introduce a new scope.
-                            let scope = self.scope_stack.pop().expect("The popped scope must be a comprehension, which must have a parent scope");
-                            self.register_attribute_assignment(
-                                object,
-                                attr,
-                                DefinitionKind::Comprehension(assignment),
-                            );
-                            self.scope_stack.push(scope);
+                        Some(CurrentAssignment::Comprehension { .. }) => {
+                            // TODO:
                         }
                         Some(CurrentAssignment::AugAssign(_)) => {
                             // TODO:
                         }
                         Some(CurrentAssignment::Named(_)) => {
-                            // A named expression whose target is an attribute is syntactically prohibited
+                            // TODO:
                         }
                         None => {}
                     }
@@ -2231,7 +2191,7 @@ where
             range: _,
         }) = pattern
         {
-            let symbol = self.add_symbol(name.id().clone());
+            let (symbol, _) = self.add_symbol(name.id().clone());
             let state = self.current_match_case.as_ref().unwrap();
             self.add_definition(
                 symbol,
@@ -2252,7 +2212,7 @@ where
             rest: Some(name), ..
         }) = pattern
         {
-            let symbol = self.add_symbol(name.id().clone());
+            let (symbol, _) = self.add_symbol(name.id().clone());
             let state = self.current_match_case.as_ref().unwrap();
             self.add_definition(
                 symbol,
@@ -2284,7 +2244,6 @@ enum CurrentAssignment<'a> {
     Comprehension {
         node: &'a ast::Comprehension,
         first: bool,
-        unpack: Option<(UnpackPosition, Unpack<'a>)>,
     },
     WithItem {
         item: &'a ast::WithItem,
@@ -2298,9 +2257,11 @@ impl CurrentAssignment<'_> {
         match self {
             Self::Assign { unpack, .. }
             | Self::For { unpack, .. }
-            | Self::WithItem { unpack, .. }
-            | Self::Comprehension { unpack, .. } => unpack.as_mut().map(|(position, _)| position),
-            Self::AnnAssign(_) | Self::AugAssign(_) | Self::Named(_) => None,
+            | Self::WithItem { unpack, .. } => unpack.as_mut().map(|(position, _)| position),
+            Self::AnnAssign(_)
+            | Self::AugAssign(_)
+            | Self::Named(_)
+            | Self::Comprehension { .. } => None,
         }
     }
 }
@@ -2355,17 +2316,13 @@ enum Unpackable<'a> {
         item: &'a ast::WithItem,
         is_async: bool,
     },
-    Comprehension {
-        first: bool,
-        node: &'a ast::Comprehension,
-    },
 }
 
 impl<'a> Unpackable<'a> {
     const fn kind(&self) -> UnpackKind {
         match self {
             Unpackable::Assign(_) => UnpackKind::Assign,
-            Unpackable::For(_) | Unpackable::Comprehension { .. } => UnpackKind::Iterable,
+            Unpackable::For(_) => UnpackKind::Iterable,
             Unpackable::WithItem { .. } => UnpackKind::ContextManager,
         }
     }
@@ -2380,11 +2337,6 @@ impl<'a> Unpackable<'a> {
                 is_async: *is_async,
                 unpack,
             },
-            Unpackable::Comprehension { node, first } => CurrentAssignment::Comprehension {
-                node,
-                first: *first,
-                unpack,
-            },
         }
     }
 }

crates/red_knot_python_semantic/src/semantic_index/definition.rs

@@ -281,9 +281,8 @@ pub(crate) struct ExceptHandlerDefinitionNodeRef<'a> {
 
 #[derive(Copy, Clone, Debug)]
 pub(crate) struct ComprehensionDefinitionNodeRef<'a> {
-    pub(crate) unpack: Option<(UnpackPosition, Unpack<'a>)>,
     pub(crate) iterable: &'a ast::Expr,
-    pub(crate) target: &'a ast::Expr,
+    pub(crate) target: &'a ast::ExprName,
     pub(crate) first: bool,
     pub(crate) is_async: bool,
 }
@@ -375,13 +374,11 @@ impl<'db> DefinitionNodeRef<'db> {
                 is_async,
             }),
             DefinitionNodeRef::Comprehension(ComprehensionDefinitionNodeRef {
-                unpack,
                 iterable,
                 target,
                 first,
                 is_async,
             }) => DefinitionKind::Comprehension(ComprehensionDefinitionKind {
-                target_kind: TargetKind::from(unpack),
                 iterable: AstNodeRef::new(parsed.clone(), iterable),
                 target: AstNodeRef::new(parsed, target),
                 first,
@@ -477,9 +474,7 @@ impl<'db> DefinitionNodeRef<'db> {
                 unpack: _,
                 is_async: _,
             }) => DefinitionNodeKey(NodeKey::from_node(target)),
-            Self::Comprehension(ComprehensionDefinitionNodeRef { target, .. }) => {
-                DefinitionNodeKey(NodeKey::from_node(target))
-            }
+            Self::Comprehension(ComprehensionDefinitionNodeRef { target, .. }) => target.into(),
             Self::VariadicPositionalParameter(node) => node.into(),
             Self::VariadicKeywordParameter(node) => node.into(),
             Self::Parameter(node) => node.into(),
@@ -555,7 +550,7 @@ pub enum DefinitionKind<'db> {
     AnnotatedAssignment(AnnotatedAssignmentDefinitionKind),
     AugmentedAssignment(AstNodeRef<ast::StmtAugAssign>),
     For(ForStmtDefinitionKind<'db>),
-    Comprehension(ComprehensionDefinitionKind<'db>),
+    Comprehension(ComprehensionDefinitionKind),
     VariadicPositionalParameter(AstNodeRef<ast::Parameter>),
     VariadicKeywordParameter(AstNodeRef<ast::Parameter>),
     Parameter(AstNodeRef<ast::ParameterWithDefault>),
@@ -754,24 +749,19 @@ impl MatchPatternDefinitionKind {
 }
 
 #[derive(Clone, Debug)]
-pub struct ComprehensionDefinitionKind<'db> {
-    pub(super) target_kind: TargetKind<'db>,
-    pub(super) iterable: AstNodeRef<ast::Expr>,
-    pub(super) target: AstNodeRef<ast::Expr>,
-    pub(super) first: bool,
-    pub(super) is_async: bool,
+pub struct ComprehensionDefinitionKind {
+    iterable: AstNodeRef<ast::Expr>,
+    target: AstNodeRef<ast::ExprName>,
+    first: bool,
+    is_async: bool,
 }
 
-impl<'db> ComprehensionDefinitionKind<'db> {
+impl ComprehensionDefinitionKind {
     pub(crate) fn iterable(&self) -> &ast::Expr {
         self.iterable.node()
     }
 
-    pub(crate) fn target_kind(&self) -> TargetKind<'db> {
-        self.target_kind
-    }
-
-    pub(crate) fn target(&self) -> &ast::Expr {
+    pub(crate) fn target(&self) -> &ast::ExprName {
         self.target.node()
     }
 

crates/red_knot_python_semantic/src/semantic_index/use_def.rs

@@ -775,16 +775,7 @@ impl<'db> UseDefMapBuilder<'db> {
             .add_and_constraint(self.scope_start_visibility, constraint);
     }
 
-    /// Snapshot the state of a single symbol at the current point in control flow.
-    ///
-    /// This is only used for `*`-import visibility constraints, which are handled differently
-    /// to most other visibility constraints. See the doc-comment for
-    /// [`Self::record_and_negate_star_import_visibility_constraint`] for more details.
-    pub(super) fn single_symbol_snapshot(&self, symbol: ScopedSymbolId) -> SymbolState {
-        self.symbol_states[symbol].clone()
-    }
-
-    /// This method exists solely for handling `*`-import visibility constraints.
+    /// This method exists solely as a fast path for handling `*`-import visibility constraints.
     ///
     /// The reason why we add visibility constraints for [`Definition`]s created by `*` imports
     /// is laid out in the doc-comment for [`StarImportPlaceholderPredicate`]. But treating these
@@ -793,11 +784,12 @@ impl<'db> UseDefMapBuilder<'db> {
     /// dominates. (Although `*` imports are not common generally, they are used in several
     /// important places by typeshed.)
     ///
-    /// To solve these regressions, it was observed that we could do significantly less work for
-    /// `*`-import definitions. We do a number of things differently here to our normal handling of
-    /// visibility constraints:
+    /// To solve these regressions, it was observed that we could add a fast path for `*`-import
+    /// definitions which added a new symbol to the global scope (as opposed to `*`-import definitions
+    /// that provided redefinitions for *pre-existing* global-scope symbols). The fast path does a
+    /// number of things differently to our normal handling of visibility constraints:
     ///
-    /// - We only apply and negate the visibility constraints to a single symbol, rather than to
+    /// - It only applies and negates the visibility constraints to a single symbol, rather than to
     ///   all symbols. This is possible here because, unlike most definitions, we know in advance that
     ///   exactly one definition occurs inside the "if-true" predicate branch, and we know exactly
     ///   which definition it is.
@@ -808,9 +800,9 @@ impl<'db> UseDefMapBuilder<'db> {
     ///   the visibility constraints is only important for symbols that did not have any new
     ///   definitions inside either the "if-predicate-true" branch or the "if-predicate-false" branch.
     ///
-    /// - We only snapshot the state for a single symbol prior to the definition, rather than doing
-    ///   expensive calls to [`Self::snapshot`]. Again, this is possible because we know
-    ///   that only a single definition occurs inside the "if-predicate-true" predicate branch.
+    /// - It avoids multiple expensive calls to [`Self::snapshot`]. This is possible because we know
+    ///   the symbol is newly added, so we know the prior state of the symbol was
+    ///   [`SymbolState::undefined`].
     ///
     /// - Normally we take care to check whether an "if-predicate-true" branch or an
     ///   "if-predicate-false" branch contains a terminal statement: these can affect the visibility
@@ -823,7 +815,6 @@ impl<'db> UseDefMapBuilder<'db> {
         &mut self,
         star_import: StarImportPlaceholderPredicate<'db>,
         symbol: ScopedSymbolId,
-        pre_definition_state: SymbolState,
     ) {
         let predicate_id = self.add_predicate(star_import.into());
         let visibility_id = self.visibility_constraints.add_atom(predicate_id);
@@ -831,9 +822,10 @@ impl<'db> UseDefMapBuilder<'db> {
             .visibility_constraints
             .add_not_constraint(visibility_id);
 
-        let mut post_definition_state =
-            std::mem::replace(&mut self.symbol_states[symbol], pre_definition_state);
-
+        let mut post_definition_state = std::mem::replace(
+            &mut self.symbol_states[symbol],
+            SymbolState::undefined(self.scope_start_visibility),
+        );
         post_definition_state
             .record_visibility_constraint(&mut self.visibility_constraints, visibility_id);
 

crates/red_knot_python_semantic/src/semantic_index/use_def/symbol_state.rs

@@ -314,7 +314,7 @@ impl SymbolBindings {
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
-pub(in crate::semantic_index) struct SymbolState {
+pub(super) struct SymbolState {
     declarations: SymbolDeclarations,
     bindings: SymbolBindings,
 }

crates/red_knot_python_semantic/src/types.rs

@@ -4605,8 +4605,8 @@ impl<'db> Type<'db> {
         match self {
             Type::TypeVar(typevar) => specialization.get(db, typevar).unwrap_or(self),
 
-            Type::FunctionLiteral(function) =>{
-                Type::FunctionLiteral(FunctionType::Specialized(SpecializedFunction::new(db, function, specialization)))
+            Type::FunctionLiteral(function) => {
+                Type::FunctionLiteral(function.apply_specialization(db, specialization))
             }
 
             // Note that we don't need to apply the specialization to `self_instance`, since it
@@ -4619,19 +4619,19 @@ impl<'db> Type<'db> {
             // specialized.)
             Type::BoundMethod(method) => Type::BoundMethod(BoundMethodType::new(
                 db,
-                FunctionType::Specialized(SpecializedFunction::new(db, method.function(db), specialization)),
+                method.function(db).apply_specialization(db, specialization),
                 method.self_instance(db),
             )),
 
             Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderGet(function)) => {
                 Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderGet(
-                FunctionType::Specialized(SpecializedFunction::new(db, function, specialization))
+                    function.apply_specialization(db, specialization),
                 ))
             }
 
             Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderCall(function)) => {
                 Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderCall(
-                FunctionType::Specialized(SpecializedFunction::new(db, function, specialization))
+                    function.apply_specialization(db, specialization),
                 ))
             }
 
@@ -5834,34 +5834,6 @@ impl<'db> FunctionSignature<'db> {
     pub(crate) fn iter(&self) -> Iter<Signature<'db>> {
         self.as_slice().iter()
     }
-
-    fn apply_specialization(&mut self, db: &'db dyn Db, specialization: Specialization<'db>) {
-        match self {
-            Self::Single(signature) => signature.apply_specialization(db, specialization),
-            Self::Overloaded(signatures, implementation) => {
-                signatures
-                    .iter_mut()
-                    .for_each(|signature| signature.apply_specialization(db, specialization));
-                implementation
-                    .as_mut()
-                    .map(|signature| signature.apply_specialization(db, specialization));
-            }
-        }
-    }
-
-    fn set_generic_context(&mut self, generic_context: GenericContext<'db>) {
-        match self {
-            Self::Single(signature) => signature.set_generic_context(generic_context),
-            Self::Overloaded(signatures, implementation) => {
-                signatures
-                    .iter_mut()
-                    .for_each(|signature| signature.set_generic_context(generic_context));
-                implementation
-                    .as_mut()
-                    .map(|signature| signature.set_generic_context(generic_context));
-            }
-        }
-    }
 }
 
 impl<'db> IntoIterator for &'db FunctionSignature<'db> {
@@ -5873,40 +5845,34 @@ impl<'db> IntoIterator for &'db FunctionSignature<'db> {
     }
 }
 
-/// A callable type that represents a single Python function.
-#[derive(
-    Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd, salsa::Supertype, salsa::Update,
-)]
-pub enum FunctionType<'db> {
-    /// A function literal in the Python AST
-    FunctionLiteral(FunctionLiteral<'db>),
+#[salsa::interned(debug)]
+pub struct FunctionType<'db> {
+    /// Name of the function at definition.
+    #[return_ref]
+    pub name: ast::name::Name,
 
-    /// A function that has a specialization applied to its signature.
-    ///
-    /// (This does not necessarily mean that the function itself is generic — the methods of a
-    /// generic class, for instance, will have the class's specialization applied so that we
-    /// correctly substitute any class typevars that appear in the signature.)
-    Specialized(SpecializedFunction<'db>),
+    /// Is this a function that we special-case somehow? If so, which one?
+    known: Option<KnownFunction>,
 
-    /// A function that we treat as generic because it inherits a containing generic context.
-    ///
-    /// This is currently only used for the `__new__` and `__init__` methods of a generic class.
-    /// That lets us pretend those methods are generic, so that we can infer a class specialization
-    /// from the arguments to its constructor.
-    InheritedGenericContext(FunctionWithInheritedGenericContext<'db>),
+    /// The scope that's created by the function, in which the function body is evaluated.
+    body_scope: ScopeId<'db>,
+
+    /// A set of special decorators that were applied to this function
+    decorators: FunctionDecorators,
+
+    /// The generic context of a generic function.
+    generic_context: Option<GenericContext<'db>>,
+
+    /// A specialization that should be applied to the function's parameter and return types,
+    /// either because the function is itself generic, or because it appears in the body of a
+    /// generic class.
+    specialization: Option<Specialization<'db>>,
 }
 
+#[salsa::tracked]
 impl<'db> FunctionType<'db> {
-    fn function_literal(self, db: &'db dyn Db) -> FunctionLiteral<'db> {
-        match self {
-            FunctionType::FunctionLiteral(literal) => literal,
-            FunctionType::Specialized(specialized) => specialized.function(db).function_literal(db),
-            FunctionType::InheritedGenericContext(inherited) => inherited.function(db),
-        }
-    }
-
     pub(crate) fn has_known_decorator(self, db: &dyn Db, decorator: FunctionDecorators) -> bool {
-        self.function_literal(db).decorators(db).contains(decorator)
+        self.decorators(db).contains(decorator)
     }
 
     /// Convert the `FunctionType` into a [`Type::Callable`].
@@ -5919,80 +5885,20 @@ impl<'db> FunctionType<'db> {
 
     /// Returns the [`FileRange`] of the function's name.
     pub fn focus_range(self, db: &dyn Db) -> FileRange {
-        let body_scope = self.function_literal(db).body_scope(db);
         FileRange::new(
-            body_scope.file(db),
-            body_scope.node(db).expect_function().name.range,
+            self.body_scope(db).file(db),
+            self.body_scope(db).node(db).expect_function().name.range,
         )
     }
 
     pub fn full_range(self, db: &dyn Db) -> FileRange {
-        let body_scope = self.function_literal(db).body_scope(db);
         FileRange::new(
-            body_scope.file(db),
-            body_scope.node(db).expect_function().range,
+            self.body_scope(db).file(db),
+            self.body_scope(db).node(db).expect_function().range,
         )
     }
 
     pub(crate) fn definition(self, db: &'db dyn Db) -> Definition<'db> {
-        self.function_literal(db).definition(db)
-    }
-
-    /// Typed externally-visible signature for this function.
-    ///
-    /// This is the signature as seen by external callers, possibly modified by decorators and/or
-    /// overloaded.
-    ///
-    /// ## Why is this a salsa query?
-    ///
-    /// This is a salsa query to short-circuit the invalidation
-    /// when the function's AST node changes.
-    ///
-    /// Were this not a salsa query, then the calling query
-    /// would depend on the function's AST and rerun for every change in that file.
-    pub(crate) fn signature(self, db: &'db dyn Db) -> FunctionSignature<'db> {
-        match self {
-            FunctionType::FunctionLiteral(literal) => literal.signature(db),
-            FunctionType::Specialized(specialized) => specialized.signature(db),
-            FunctionType::InheritedGenericContext(inherited) => inherited.signature(db),
-        }
-    }
-
-    pub(crate) fn known(self, db: &'db dyn Db) -> Option<KnownFunction> {
-        self.function_literal(db).known(db)
-    }
-
-    pub(crate) fn is_known(self, db: &'db dyn Db, known_function: KnownFunction) -> bool {
-        self.known(db) == Some(known_function)
-    }
-}
-
-#[salsa::interned(debug)]
-pub struct FunctionLiteral<'db> {
-    /// Name of the function at definition.
-    #[return_ref]
-    pub name: ast::name::Name,
-
-    /// Is this a function that we special-case somehow? If so, which one?
-    known: Option<KnownFunction>,
-
-    /// The scope that's created by the function, in which the function body is evaluated.
-    body_scope: ScopeId<'db>,
-
-    /// The scope containing the PEP 695 type parameters in the function definition, if any.
-    type_params_scope: Option<ScopeId<'db>>,
-
-    /// A set of special decorators that were applied to this function
-    decorators: FunctionDecorators,
-}
-
-#[salsa::tracked]
-impl<'db> FunctionLiteral<'db> {
-    fn has_known_decorator(self, db: &dyn Db, decorator: FunctionDecorators) -> bool {
-        self.decorators(db).contains(decorator)
-    }
-
-    fn definition(self, db: &'db dyn Db) -> Definition<'db> {
         let body_scope = self.body_scope(db);
         let index = semantic_index(db, body_scope.file(db));
         index.expect_single_definition(body_scope.node(db).expect_function())
@@ -6010,9 +5916,13 @@ impl<'db> FunctionLiteral<'db> {
     ///
     /// Were this not a salsa query, then the calling query
     /// would depend on the function's AST and rerun for every change in that file.
-    #[salsa::tracked]
-    fn signature(self, db: &'db dyn Db) -> FunctionSignature<'db> {
-        let internal_signature = self.internal_signature(db);
+    #[salsa::tracked(return_ref)]
+    pub(crate) fn signature(self, db: &'db dyn Db) -> FunctionSignature<'db> {
+        let mut internal_signature = self.internal_signature(db);
+
+        if let Some(specialization) = self.specialization(db) {
+            internal_signature = internal_signature.apply_specialization(db, specialization);
+        }
 
         // The semantic model records a use for each function on the name node. This is used here
         // to get the previous function definition with the same name.
@@ -6072,61 +5982,39 @@ impl<'db> FunctionLiteral<'db> {
         let scope = self.body_scope(db);
         let function_stmt_node = scope.node(db).expect_function();
         let definition = self.definition(db);
-        let generic_context = function_stmt_node.type_params.as_ref().map(|type_params| {
-            let index = semantic_index(db, scope.file(db));
-            GenericContext::from_type_params(db, index, type_params)
-        });
-        Signature::from_function(db, generic_context, definition, function_stmt_node)
+        Signature::from_function(db, self.generic_context(db), definition, function_stmt_node)
     }
 
-    fn with_generic_context(
-        self,
-        db: &'db dyn Db,
-        generic_context: GenericContext<'db>,
-    ) -> FunctionType<'db> {
-        FunctionType::InheritedGenericContext(FunctionWithInheritedGenericContext::new(
+    pub(crate) fn is_known(self, db: &'db dyn Db, known_function: KnownFunction) -> bool {
+        self.known(db) == Some(known_function)
+    }
+
+    fn with_generic_context(self, db: &'db dyn Db, generic_context: GenericContext<'db>) -> Self {
+        Self::new(
             db,
-            self,
-            generic_context,
-        ))
+            self.name(db).clone(),
+            self.known(db),
+            self.body_scope(db),
+            self.decorators(db),
+            Some(generic_context),
+            self.specialization(db),
+        )
     }
-}
 
-impl<'db> From<FunctionLiteral<'db>> for Type<'db> {
-    fn from(literal: FunctionLiteral<'db>) -> Type<'db> {
-        Type::FunctionLiteral(FunctionType::FunctionLiteral(literal))
-    }
-}
-
-#[salsa::interned(debug)]
-pub struct SpecializedFunction<'db> {
-    function: FunctionType<'db>,
-    specialization: Specialization<'db>,
-}
-
-#[salsa::tracked]
-impl<'db> SpecializedFunction<'db> {
-    #[salsa::tracked]
-    fn signature(self, db: &'db dyn Db) -> FunctionSignature<'db> {
-        let mut signature = self.function(db).signature(db);
-        signature.apply_specialization(db, self.specialization(db));
-        signature
-    }
-}
-
-#[salsa::interned(debug)]
-pub struct FunctionWithInheritedGenericContext<'db> {
-    function: FunctionLiteral<'db>,
-    generic_context: GenericContext<'db>,
-}
-
-#[salsa::tracked]
-impl<'db> FunctionWithInheritedGenericContext<'db> {
-    #[salsa::tracked]
-    fn signature(self, db: &'db dyn Db) -> FunctionSignature<'db> {
-        let mut signature = self.function(db).signature(db);
-        signature.set_generic_context(self.generic_context(db));
-        signature
+    fn apply_specialization(self, db: &'db dyn Db, specialization: Specialization<'db>) -> Self {
+        let specialization = match self.specialization(db) {
+            Some(existing) => existing.apply_specialization(db, specialization),
+            None => specialization,
+        };
+        Self::new(
+            db,
+            self.name(db).clone(),
+            self.known(db),
+            self.body_scope(db),
+            self.decorators(db),
+            self.generic_context(db),
+            Some(specialization),
+        )
     }
 }
 
@@ -6342,11 +6230,9 @@ impl<'db> CallableType<'db> {
     fn apply_specialization(self, db: &'db dyn Db, specialization: Specialization<'db>) -> Self {
         CallableType::from_overloads(
             db,
-            self.signatures(db).iter().map(|signature| {
-                let mut signature = signature.clone();
-                signature.apply_specialization(db, specialization);
-                signature
-            }),
+            self.signatures(db)
+                .iter()
+                .map(|signature| signature.apply_specialization(db, specialization)),
         )
     }
 

crates/red_knot_python_semantic/src/types/call/bind.rs

@@ -219,8 +219,7 @@ impl<'db> Bindings<'db> {
 
             match binding_type {
                 Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderGet(function)) => {
-                    let function_literal = function.function_literal(db);
-                    if function_literal.has_known_decorator(db, FunctionDecorators::CLASSMETHOD) {
+                    if function.has_known_decorator(db, FunctionDecorators::CLASSMETHOD) {
                         match overload.parameter_types() {
                             [_, Some(owner)] => {
                                 overload.set_return_type(Type::BoundMethod(BoundMethodType::new(
@@ -251,9 +250,7 @@ impl<'db> Bindings<'db> {
                     if let [Some(function_ty @ Type::FunctionLiteral(function)), ..] =
                         overload.parameter_types()
                     {
-                        let function_literal = function.function_literal(db);
-                        if function_literal.has_known_decorator(db, FunctionDecorators::CLASSMETHOD)
-                        {
+                        if function.has_known_decorator(db, FunctionDecorators::CLASSMETHOD) {
                             match overload.parameter_types() {
                                 [_, _, Some(owner)] => {
                                     overload.set_return_type(Type::BoundMethod(
@@ -301,7 +298,7 @@ impl<'db> Bindings<'db> {
                             if property.getter(db).is_some_and(|getter| {
                                 getter
                                     .into_function_literal()
-                                    .is_some_and(|f| f.function_literal(db).name(db) == "__name__")
+                                    .is_some_and(|f| f.name(db) == "__name__")
                             }) =>
                         {
                             overload.set_return_type(Type::string_literal(db, type_alias.name(db)));
@@ -310,7 +307,7 @@ impl<'db> Bindings<'db> {
                             if property.getter(db).is_some_and(|getter| {
                                 getter
                                     .into_function_literal()
-                                    .is_some_and(|f| f.function_literal(db).name(db) == "__name__")
+                                    .is_some_and(|f| f.name(db) == "__name__")
                             }) =>
                         {
                             overload.set_return_type(Type::string_literal(db, type_var.name(db)));
@@ -419,12 +416,7 @@ impl<'db> Bindings<'db> {
                 Type::BoundMethod(bound_method)
                     if bound_method.self_instance(db).is_property_instance() =>
                 {
-                    match bound_method
-                        .function(db)
-                        .function_literal(db)
-                        .name(db)
-                        .as_str()
-                    {
+                    match bound_method.function(db).name(db).as_str() {
                         "setter" => {
                             if let [Some(_), Some(setter)] = overload.parameter_types() {
                                 let mut ty_property = bound_method.self_instance(db);
@@ -464,10 +456,7 @@ impl<'db> Bindings<'db> {
                     }
                 }
 
-                Type::FunctionLiteral(function_type) => match function_type
-                    .function_literal(db)
-                    .known(db)
-                {
+                Type::FunctionLiteral(function_type) => match function_type.known(db) {
                     Some(KnownFunction::IsEquivalentTo) => {
                         if let [Some(ty_a), Some(ty_b)] = overload.parameter_types() {
                             overload.set_return_type(Type::BooleanLiteral(
@@ -546,15 +535,6 @@ impl<'db> Bindings<'db> {
                         }
                     }
 
-                    Some(KnownFunction::IsProtocol) => {
-                        if let [Some(ty)] = overload.parameter_types() {
-                            overload.set_return_type(Type::BooleanLiteral(
-                                ty.into_class_literal()
-                                    .is_some_and(|class| class.is_protocol(db)),
-                            ));
-                        }
-                    }
-
                     Some(KnownFunction::Overload) => {
                         // TODO: This can be removed once we understand legacy generics because the
                         // typeshed definition for `typing.overload` is an identity function.
@@ -1186,7 +1166,7 @@ impl<'db> CallableDescription<'db> {
         match callable_type {
             Type::FunctionLiteral(function) => Some(CallableDescription {
                 kind: "function",
-                name: function.function_literal(db).name(db),
+                name: function.name(db),
             }),
             Type::ClassLiteral(class_type) => Some(CallableDescription {
                 kind: "class",
@@ -1194,12 +1174,12 @@ impl<'db> CallableDescription<'db> {
             }),
             Type::BoundMethod(bound_method) => Some(CallableDescription {
                 kind: "bound method",
-                name: bound_method.function(db).function_literal(db).name(db),
+                name: bound_method.function(db).name(db),
             }),
             Type::MethodWrapper(MethodWrapperKind::FunctionTypeDunderGet(function)) => {
                 Some(CallableDescription {
                     kind: "method wrapper `__get__` of function",
-                    name: function.function_literal(db).name(db),
+                    name: function.name(db),
                 })
             }
             Type::MethodWrapper(MethodWrapperKind::PropertyDunderGet(_)) => {
@@ -1324,7 +1304,7 @@ impl<'db> BindingError<'db> {
     ) -> Option<(Span, Span)> {
         match callable_ty {
             Type::FunctionLiteral(function) => {
-                let function_scope = function.function_literal(db).body_scope(db);
+                let function_scope = function.body_scope(db);
                 let span = Span::from(function_scope.file(db));
                 let node = function_scope.node(db);
                 if let Some(func_def) = node.as_function() {

crates/red_knot_python_semantic/src/types/class.rs

@@ -582,17 +582,6 @@ impl<'db> ClassLiteralType<'db> {
             .collect()
     }
 
-    /// Determine if this class is a protocol.
-    pub(super) fn is_protocol(self, db: &'db dyn Db) -> bool {
-        self.explicit_bases(db).iter().any(|base| {
-            matches!(
-                base,
-                Type::KnownInstance(KnownInstanceType::Protocol)
-                    | Type::Dynamic(DynamicType::SubscriptedProtocol)
-            )
-        })
-    }
-
     /// Return the types of the decorators on this class
     #[salsa::tracked(return_ref)]
     fn decorators(self, db: &'db dyn Db) -> Box<[Type<'db>]> {
@@ -962,9 +951,7 @@ impl<'db> ClassLiteralType<'db> {
                     Some(_),
                     "__new__" | "__init__",
                 ) => Type::FunctionLiteral(
-                    function
-                        .function_literal(db)
-                        .with_generic_context(db, origin.generic_context(db)),
+                    function.with_generic_context(db, origin.generic_context(db)),
                 ),
                 _ => ty,
             }
@@ -1429,42 +1416,14 @@ impl<'db> ClassLiteralType<'db> {
                             }
                         }
                     }
-                    DefinitionKind::Comprehension(comprehension) => {
-                        match comprehension.target_kind() {
-                            TargetKind::Sequence(_, unpack) => {
-                                // We found an unpacking assignment like:
-                                //
-                                //     [... for .., self.name, .. in <iterable>]
-
-                                let unpacked = infer_unpack_types(db, unpack);
-                                let target_ast_id = comprehension
-                                    .target()
-                                    .scoped_expression_id(db, unpack.target_scope(db));
-                                let inferred_ty = unpacked.expression_type(target_ast_id);
-
-                                union_of_inferred_types = union_of_inferred_types.add(inferred_ty);
-                            }
-                            TargetKind::NameOrAttribute => {
-                                // We found an attribute assignment like:
-                                //
-                                //     [... for self.name in <iterable>]
-
-                                let iterable_ty = infer_expression_type(
-                                    db,
-                                    index.expression(comprehension.iterable()),
-                                );
-                                // TODO: Potential diagnostics resulting from the iterable are currently not reported.
-                                let inferred_ty = iterable_ty.iterate(db);
-
-                                union_of_inferred_types = union_of_inferred_types.add(inferred_ty);
-                            }
-                        }
+                    DefinitionKind::Comprehension(_) => {
+                        // TODO:
                     }
                     DefinitionKind::AugmentedAssignment(_) => {
                         // TODO:
                     }
                     DefinitionKind::NamedExpression(_) => {
-                        // A named expression whose target is an attribute is syntactically prohibited
+                        // TODO:
                     }
                     _ => {}
                 }

crates/red_knot_python_semantic/src/types/context.rs

@@ -169,9 +169,7 @@ impl<'db> InferContext<'db> {
 
                 // Iterate over all functions and test if any is decorated with `@no_type_check`.
                 function_scope_tys.any(|function_ty| {
-                    function_ty
-                        .function_literal(self.db)
-                        .has_known_decorator(self.db, FunctionDecorators::NO_TYPE_CHECK)
+                    function_ty.has_known_decorator(self.db, FunctionDecorators::NO_TYPE_CHECK)
                 })
             }
             InNoTypeCheck::Yes => true,

crates/red_knot_python_semantic/src/types/diagnostic.rs

@@ -36,7 +36,6 @@ pub(crate) fn register_lints(registry: &mut LintRegistryBuilder) {
     registry.register_lint(&INVALID_EXCEPTION_CAUGHT);
     registry.register_lint(&INVALID_METACLASS);
     registry.register_lint(&INVALID_PARAMETER_DEFAULT);
-    registry.register_lint(&INVALID_PROTOCOL);
     registry.register_lint(&INVALID_RAISE);
     registry.register_lint(&INVALID_SUPER_ARGUMENT);
     registry.register_lint(&INVALID_TYPE_CHECKING_CONSTANT);
@@ -231,34 +230,6 @@ declare_lint! {
     }
 }
 
-declare_lint! {
-    /// ## What it does
-    /// Checks for invalidly defined protocol classes.
-    ///
-    /// ## Why is this bad?
-    /// An invalidly defined protocol class may lead to the type checker inferring
-    /// unexpected things. It may also lead to `TypeError`s at runtime.
-    ///
-    /// ## Examples
-    /// A `Protocol` class cannot inherit from a non-`Protocol` class;
-    /// this raises a `TypeError` at runtime:
-    ///
-    /// ```pycon
-    /// >>> from typing import Protocol
-    /// >>> class Foo(int, Protocol): ...
-    /// ...
-    /// Traceback (most recent call last):
-    ///   File "<python-input-1>", line 1, in <module>
-    ///     class Foo(int, Protocol): ...
-    /// TypeError: Protocols can only inherit from other protocols, got <class 'int'>
-    /// ```
-    pub(crate) static INVALID_PROTOCOL = {
-        summary: "detects invalid protocol class definitions",
-        status: LintStatus::preview("1.0.0"),
-        default_level: Level::Error,
-    }
-}
-
 declare_lint! {
     /// TODO #14889
     pub(crate) static INCONSISTENT_MRO = {
@@ -1125,7 +1096,7 @@ fn report_invalid_assignment_with_message(
         Type::FunctionLiteral(function) => {
             context.report_lint_old(&INVALID_ASSIGNMENT, node, format_args!(
                     "Implicit shadowing of function `{}`; annotate to make it explicit if this is intentional",
-                    function.function_literal(context.db()).name(context.db())));
+                    function.name(context.db())));
         }
         _ => {
             context.report_lint_old(&INVALID_ASSIGNMENT, node, message);

crates/red_knot_python_semantic/src/types/display.rs

@@ -10,7 +10,7 @@ use crate::types::class::{ClassType, GenericAlias, GenericClass};
 use crate::types::generics::{GenericContext, Specialization};
 use crate::types::signatures::{Parameter, Parameters, Signature};
 use crate::types::{
-    FunctionSignature, FunctionType, InstanceType, IntersectionType, KnownClass, MethodWrapperKind,
+    FunctionSignature, InstanceType, IntersectionType, KnownClass, MethodWrapperKind,
     StringLiteralType, SubclassOfInner, Type, TypeVarBoundOrConstraints, TypeVarInstance,
     UnionType, WrapperDescriptorKind,
 };
@@ -108,7 +108,7 @@ impl Display for DisplayRepresentation<'_> {
                             f,
                             // "def {name}{specialization}{signature}",
                             "def {name}{signature}",
-                            name = function.function_literal(self.db).name(self.db),
+                            name = function.name(self.db),
                             signature = signature.display(self.db)
                         )
                     }
@@ -135,7 +135,7 @@ impl Display for DisplayRepresentation<'_> {
                         write!(
                             f,
                             "bound method {instance}.{method}{signature}",
-                            method = function.function_literal(self.db).name(self.db),
+                            method = function.name(self.db),
                             instance = bound_method.self_instance(self.db).display(self.db),
                             signature = signature.bind_self().display(self.db)
                         )
@@ -155,12 +155,10 @@ impl Display for DisplayRepresentation<'_> {
                 write!(
                     f,
                     "<method-wrapper `__get__` of `{function}{specialization}`>",
-                    function = function.function_literal(self.db).name(self.db),
-                    specialization = if let FunctionType::Specialized(specialized) = function {
-                        specialized
-                            .specialization(self.db)
-                            .display_short(self.db)
-                            .to_string()
+                    function = function.name(self.db),
+                    specialization = if let Some(specialization) = function.specialization(self.db)
+                    {
+                        specialization.display_short(self.db).to_string()
                     } else {
                         String::new()
                     },
@@ -170,12 +168,10 @@ impl Display for DisplayRepresentation<'_> {
                 write!(
                     f,
                     "<method-wrapper `__call__` of `{function}{specialization}`>",
-                    function = function.function_literal(self.db).name(self.db),
-                    specialization = if let FunctionType::Specialized(specialized) = function {
-                        specialized
-                            .specialization(self.db)
-                            .display_short(self.db)
-                            .to_string()
+                    function = function.name(self.db),
+                    specialization = if let Some(specialization) = function.specialization(self.db)
+                    {
+                        specialization.display_short(self.db).to_string()
                     } else {
                         String::new()
                     },

crates/red_knot_python_semantic/src/types/infer.rs

@@ -49,9 +49,9 @@ use crate::module_resolver::resolve_module;
 use crate::node_key::NodeKey;
 use crate::semantic_index::ast_ids::{HasScopedExpressionId, HasScopedUseId, ScopedExpressionId};
 use crate::semantic_index::definition::{
-    AnnotatedAssignmentDefinitionKind, AssignmentDefinitionKind, ComprehensionDefinitionKind,
-    Definition, DefinitionKind, DefinitionNodeKey, ExceptHandlerDefinitionKind,
-    ForStmtDefinitionKind, TargetKind, WithItemDefinitionKind,
+    AnnotatedAssignmentDefinitionKind, AssignmentDefinitionKind, Definition, DefinitionKind,
+    DefinitionNodeKey, ExceptHandlerDefinitionKind, ForStmtDefinitionKind, TargetKind,
+    WithItemDefinitionKind,
 };
 use crate::semantic_index::expression::{Expression, ExpressionKind};
 use crate::semantic_index::symbol::{
@@ -81,13 +81,13 @@ use crate::types::generics::GenericContext;
 use crate::types::mro::MroErrorKind;
 use crate::types::unpacker::{UnpackResult, Unpacker};
 use crate::types::{
-    binding_type, todo_type, CallDunderError, CallableSignature, CallableType, Class,
-    ClassLiteralType, ClassType, DataclassMetadata, DynamicType, FunctionDecorators,
-    FunctionLiteral, GenericAlias, GenericClass, IntersectionBuilder, IntersectionType, KnownClass,
-    KnownFunction, KnownInstanceType, MemberLookupPolicy, MetaclassCandidate, NonGenericClass,
-    Parameter, ParameterForm, Parameters, Signature, Signatures, SliceLiteralType,
-    StringLiteralType, SubclassOfType, Symbol, SymbolAndQualifiers, Truthiness, TupleType, Type,
-    TypeAliasType, TypeAndQualifiers, TypeArrayDisplay, TypeQualifiers, TypeVarBoundOrConstraints,
+    todo_type, CallDunderError, CallableSignature, CallableType, Class, ClassLiteralType,
+    ClassType, DataclassMetadata, DynamicType, FunctionDecorators, FunctionType, GenericAlias,
+    GenericClass, IntersectionBuilder, IntersectionType, KnownClass, KnownFunction,
+    KnownInstanceType, MemberLookupPolicy, MetaclassCandidate, NonGenericClass, Parameter,
+    ParameterForm, Parameters, Signature, Signatures, SliceLiteralType, StringLiteralType,
+    SubclassOfType, Symbol, SymbolAndQualifiers, Truthiness, TupleType, Type, TypeAliasType,
+    TypeAndQualifiers, TypeArrayDisplay, TypeQualifiers, TypeVarBoundOrConstraints,
     TypeVarInstance, UnionBuilder, UnionType,
 };
 use crate::unpack::{Unpack, UnpackPosition};
@@ -99,8 +99,8 @@ use super::diagnostic::{
     report_index_out_of_bounds, report_invalid_exception_caught, report_invalid_exception_cause,
     report_invalid_exception_raised, report_invalid_type_checking_constant,
     report_non_subscriptable, report_possibly_unresolved_reference, report_slice_step_size_zero,
-    report_unresolved_reference, INVALID_METACLASS, INVALID_PROTOCOL, REDUNDANT_CAST,
-    STATIC_ASSERT_ERROR, SUBCLASS_OF_FINAL_CLASS, TYPE_ASSERTION_FAILURE,
+    report_unresolved_reference, INVALID_METACLASS, REDUNDANT_CAST, STATIC_ASSERT_ERROR,
+    SUBCLASS_OF_FINAL_CLASS, TYPE_ASSERTION_FAILURE,
 };
 use super::slots::check_class_slots;
 use super::string_annotation::{
@@ -306,7 +306,7 @@ pub(super) fn infer_unpack_types<'db>(db: &'db dyn Db, unpack: Unpack<'db>) -> U
     let _span =
         tracing::trace_span!("infer_unpack_types", range=?unpack.range(db), ?file).entered();
 
-    let mut unpacker = Unpacker::new(db, unpack.target_scope(db), unpack.value_scope(db));
+    let mut unpacker = Unpacker::new(db, unpack.scope(db));
     unpacker.unpack(unpack.target(db), unpack.value(db));
     unpacker.finish()
 }
@@ -763,21 +763,17 @@ impl<'db> TypeInferenceBuilder<'db> {
                 continue;
             }
 
-            let is_protocol = class.is_protocol(self.db());
-
-            // (2) Iterate through the class's explicit bases to check for various possible errors:
-            //     - Check for inheritance from plain `Generic`,
-            //     - Check for inheritance from a `@final` classes
-            //     - If the class is a protocol class: check for inheritance from a non-protocol class
+            // (2) Check for inheritance from plain `Generic`,
+            //     and from classes that inherit from `@final` classes
             for (i, base_class) in class.explicit_bases(self.db()).iter().enumerate() {
                 let base_class = match base_class {
                     Type::KnownInstance(KnownInstanceType::Generic) => {
-                        // Unsubscripted `Generic` can appear in the MRO of many classes,
+                        // `Generic` can appear in the MRO of many classes,
                         // but it is never valid as an explicit base class in user code.
                         self.context.report_lint_old(
                             &INVALID_BASE,
                             &class_node.bases()[i],
-                            format_args!("Cannot inherit from plain `Generic`"),
+                            format_args!("Cannot inherit from plain `Generic`",),
                         );
                         continue;
                     }
@@ -786,32 +782,18 @@ impl<'db> TypeInferenceBuilder<'db> {
                     _ => continue,
                 };
 
-                if is_protocol
-                    && !(base_class.is_protocol(self.db())
-                        || base_class.is_known(self.db(), KnownClass::Object))
-                {
-                    self.context.report_lint_old(
-                        &INVALID_PROTOCOL,
-                        &class_node.bases()[i],
-                        format_args!(
-                            "Protocol class `{}` cannot inherit from non-protocol class `{}`",
-                            class.name(self.db()),
-                            base_class.name(self.db()),
-                        ),
-                    );
-                }
-
-                if base_class.is_final(self.db()) {
-                    self.context.report_lint_old(
-                        &SUBCLASS_OF_FINAL_CLASS,
-                        &class_node.bases()[i],
-                        format_args!(
-                            "Class `{}` cannot inherit from final class `{}`",
-                            class.name(self.db()),
-                            base_class.name(self.db()),
-                        ),
-                    );
+                if !base_class.is_final(self.db()) {
+                    continue;
                 }
+                self.context.report_lint_old(
+                    &SUBCLASS_OF_FINAL_CLASS,
+                    &class_node.bases()[i],
+                    format_args!(
+                        "Class `{}` cannot inherit from final class `{}`",
+                        class.name(self.db()),
+                        base_class.name(self.db()),
+                    ),
+                );
             }
 
             // (3) Check that the class's MRO is resolvable
@@ -964,7 +946,13 @@ impl<'db> TypeInferenceBuilder<'db> {
                 self.infer_named_expression_definition(named_expression.node(), definition);
             }
             DefinitionKind::Comprehension(comprehension) => {
-                self.infer_comprehension_definition(comprehension, definition);
+                self.infer_comprehension_definition(
+                    comprehension.iterable(),
+                    comprehension.target(),
+                    comprehension.is_first(),
+                    comprehension.is_async(),
+                    definition,
+                );
             }
             DefinitionKind::VariadicPositionalParameter(parameter) => {
                 self.infer_variadic_positional_parameter_definition(parameter, definition);
@@ -1242,7 +1230,7 @@ impl<'db> TypeInferenceBuilder<'db> {
 
     /// Returns `true` if the current scope is the function body scope of a method of a protocol
     /// (that is, a class which directly inherits `typing.Protocol`.)
-    fn in_protocol_class(&self) -> bool {
+    fn in_class_that_inherits_protocol_directly(&self) -> bool {
         let current_scope_id = self.scope().file_scope_id(self.db());
         let current_scope = self.index.scope(current_scope_id);
         let Some(parent_scope_id) = current_scope.parent() else {
@@ -1270,13 +1258,13 @@ impl<'db> TypeInferenceBuilder<'db> {
             return false;
         };
 
-        let class_definition = self.index.expect_single_definition(node_ref.node());
-
-        let Type::ClassLiteral(class) = binding_type(self.db(), class_definition) else {
-            return false;
-        };
-
-        class.is_protocol(self.db())
+        // TODO move this to `Class` once we add proper `Protocol` support
+        node_ref.bases().iter().any(|base| {
+            matches!(
+                self.file_expression_type(base),
+                Type::KnownInstance(KnownInstanceType::Protocol)
+            )
+        })
     }
 
     /// Returns `true` if the current scope is the function body scope of a function overload (that
@@ -1340,7 +1328,7 @@ impl<'db> TypeInferenceBuilder<'db> {
 
             if (self.in_stub()
                 || self.in_function_overload_or_abstractmethod()
-                || self.in_protocol_class())
+                || self.in_class_that_inherits_protocol_directly())
                 && self.return_types_and_ranges.is_empty()
                 && is_stub_suite(&function.body)
             {
@@ -1503,6 +1491,10 @@ impl<'db> TypeInferenceBuilder<'db> {
             }
         }
 
+        let generic_context = type_params.as_ref().map(|type_params| {
+            GenericContext::from_type_params(self.db(), self.index, type_params)
+        });
+
         let function_kind =
             KnownFunction::try_from_definition_and_name(self.db(), definition, name);
 
@@ -1511,19 +1503,16 @@ impl<'db> TypeInferenceBuilder<'db> {
             .node_scope(NodeWithScopeRef::Function(function))
             .to_scope_id(self.db(), self.file());
 
-        let type_params_scope = type_params.as_ref().map(|_| {
-            self.index
-                .node_scope(NodeWithScopeRef::FunctionTypeParameters(function))
-                .to_scope_id(self.db(), self.file())
-        });
+        let specialization = None;
 
-        let mut inferred_ty = Type::from(FunctionLiteral::new(
+        let mut inferred_ty = Type::FunctionLiteral(FunctionType::new(
             self.db(),
             &name.id,
             function_kind,
             body_scope,
-            type_params_scope,
             function_decorators,
+            generic_context,
+            specialization,
         ));
 
         for (decorator_ty, decorator_node) in decorator_types_and_nodes.iter().rev() {
@@ -1642,7 +1631,7 @@ impl<'db> TypeInferenceBuilder<'db> {
                     }
                 } else if (self.in_stub()
                     || self.in_function_overload_or_abstractmethod()
-                    || self.in_protocol_class())
+                    || self.in_class_that_inherits_protocol_directly())
                     && default
                         .as_ref()
                         .is_some_and(|d| d.is_ellipsis_literal_expr())
@@ -1948,13 +1937,11 @@ impl<'db> TypeInferenceBuilder<'db> {
         for item in items {
             let target = item.optional_vars.as_deref();
             if let Some(target) = target {
-                self.infer_target(target, &item.context_expr, |builder, context_expr| {
+                self.infer_target(target, &item.context_expr, |db, ctx_manager_ty| {
                     // TODO: `infer_with_statement_definition` reports a diagnostic if `ctx_manager_ty` isn't a context manager
                     //  but only if the target is a name. We should report a diagnostic here if the target isn't a name:
                     //  `with not_context_manager as a.x: ...
-                    builder
-                        .infer_standalone_expression(context_expr)
-                        .enter(builder.db())
+                    ctx_manager_ty.enter(db)
                 });
             } else {
                 // Call into the context expression inference to validate that it evaluates
@@ -2360,9 +2347,7 @@ impl<'db> TypeInferenceBuilder<'db> {
         } = assignment;
 
         for target in targets {
-            self.infer_target(target, value, |builder, value_expr| {
-                builder.infer_standalone_expression(value_expr)
-            });
+            self.infer_target(target, value, |_, ty| ty);
         }
     }
 
@@ -2372,16 +2357,23 @@ impl<'db> TypeInferenceBuilder<'db> {
     /// targets (unpacking). If `target` is an attribute expression, we check that the assignment
     /// is valid. For 'target's that are definitions, this check happens elsewhere.
     ///
-    /// The `infer_value_expr` function is used to infer the type of the `value` expression which
-    /// are not `Name` expressions. The returned type is the one that is eventually assigned to the
-    /// `target`.
-    fn infer_target<F>(&mut self, target: &ast::Expr, value: &ast::Expr, infer_value_expr: F)
+    /// The `to_assigned_ty` function is used to convert the inferred type of the `value` expression
+    /// to the type that is eventually assigned to the `target`.
+    ///
+    /// # Panics
+    ///
+    /// If the `value` is not a standalone expression.
+    fn infer_target<F>(&mut self, target: &ast::Expr, value: &ast::Expr, to_assigned_ty: F)
     where
-        F: Fn(&mut TypeInferenceBuilder<'db>, &ast::Expr) -> Type<'db>,
+        F: Fn(&'db dyn Db, Type<'db>) -> Type<'db>,
     {
         let assigned_ty = match target {
             ast::Expr::Name(_) => None,
-            _ => Some(infer_value_expr(self, value)),
+            _ => {
+                let value_ty = self.infer_standalone_expression(value);
+
+                Some(to_assigned_ty(self.db(), value_ty))
+            }
         };
         self.infer_target_impl(target, assigned_ty);
     }
@@ -3134,13 +3126,11 @@ impl<'db> TypeInferenceBuilder<'db> {
             is_async: _,
         } = for_statement;
 
-        self.infer_target(target, iter, |builder, iter_expr| {
+        self.infer_target(target, iter, |db, iter_ty| {
             // TODO: `infer_for_statement_definition` reports a diagnostic if `iter_ty` isn't iterable
             //  but only if the target is a name. We should report a diagnostic here if the target isn't a name:
             //  `for a.x in not_iterable: ...
-            builder
-                .infer_standalone_expression(iter_expr)
-                .iterate(builder.db())
+            iter_ty.iterate(db)
         });
 
         self.infer_body(body);
@@ -3969,17 +3959,15 @@ impl<'db> TypeInferenceBuilder<'db> {
             is_async: _,
         } = comprehension;
 
-        self.infer_target(target, iter, |builder, iter_expr| {
-            // TODO: `infer_comprehension_definition` reports a diagnostic if `iter_ty` isn't iterable
-            //  but only if the target is a name. We should report a diagnostic here if the target isn't a name:
-            //  `[... for a.x in not_iterable]
-            if is_first {
-                infer_same_file_expression_type(builder.db(), builder.index.expression(iter_expr))
-            } else {
-                builder.infer_standalone_expression(iter_expr)
-            }
-            .iterate(builder.db())
-        });
+        if !is_first {
+            self.infer_standalone_expression(iter);
+        }
+        // TODO more complex assignment targets
+        if let ast::Expr::Name(name) = target {
+            self.infer_definition(name);
+        } else {
+            self.infer_expression(target);
+        }
         for expr in ifs {
             self.infer_expression(expr);
         }
@@ -3987,12 +3975,12 @@ impl<'db> TypeInferenceBuilder<'db> {
 
     fn infer_comprehension_definition(
         &mut self,
-        comprehension: &ComprehensionDefinitionKind<'db>,
+        iterable: &ast::Expr,
+        target: &ast::ExprName,
+        is_first: bool,
+        is_async: bool,
         definition: Definition<'db>,
     ) {
-        let iterable = comprehension.iterable();
-        let target = comprehension.target();
-
         let expression = self.index.expression(iterable);
         let result = infer_expression_types(self.db(), expression);
 
@@ -4002,7 +3990,7 @@ impl<'db> TypeInferenceBuilder<'db> {
         // (2) We must *not* call `self.extend()` on the result of the type inference,
         //     because `ScopedExpressionId`s are only meaningful within their own scope, so
         //     we'd add types for random wrong expressions in the current scope
-        let iterable_type = if comprehension.is_first() {
+        let iterable_type = if is_first {
             let lookup_scope = self
                 .index
                 .parent_scope_id(self.scope().file_scope_id(self.db()))
@@ -4014,26 +4002,14 @@ impl<'db> TypeInferenceBuilder<'db> {
             result.expression_type(iterable.scoped_expression_id(self.db(), self.scope()))
         };
 
-        let target_type = if comprehension.is_async() {
+        let target_type = if is_async {
             // TODO: async iterables/iterators! -- Alex
             todo_type!("async iterables/iterators")
         } else {
-            match comprehension.target_kind() {
-                TargetKind::Sequence(unpack_position, unpack) => {
-                    let unpacked = infer_unpack_types(self.db(), unpack);
-                    if unpack_position == UnpackPosition::First {
-                        self.context.extend(unpacked.diagnostics());
-                    }
-                    let target_ast_id = target.scoped_expression_id(self.db(), self.scope());
-                    unpacked.expression_type(target_ast_id)
-                }
-                TargetKind::NameOrAttribute => {
-                    iterable_type.try_iterate(self.db()).unwrap_or_else(|err| {
-                        err.report_diagnostic(&self.context, iterable_type, iterable.into());
-                        err.fallback_element_type(self.db())
-                    })
-                }
-            }
+            iterable_type.try_iterate(self.db()).unwrap_or_else(|err| {
+                err.report_diagnostic(&self.context, iterable_type, iterable.into());
+                err.fallback_element_type(self.db())
+            })
         };
 
         self.types.expressions.insert(

crates/red_knot_python_semantic/src/types/signatures.rs

@@ -289,18 +289,17 @@ impl<'db> Signature<'db> {
     }
 
     pub(crate) fn apply_specialization(
-        &mut self,
+        &self,
         db: &'db dyn Db,
         specialization: Specialization<'db>,
-    ) {
-        self.parameters.apply_specialization(db, specialization);
-        self.return_ty
-            .as_mut()
-            .map(|ty| *ty = ty.apply_specialization(db, specialization));
-    }
-
-    pub(crate) fn set_generic_context(&mut self, generic_context: GenericContext<'db>) {
-        self.generic_context = Some(generic_context);
+    ) -> Self {
+        Self {
+            generic_context: self.generic_context,
+            parameters: self.parameters.apply_specialization(db, specialization),
+            return_ty: self
+                .return_ty
+                .map(|ty| ty.apply_specialization(db, specialization)),
+        }
     }
 
     /// Return the parameters in this signature.
@@ -1001,10 +1000,15 @@ impl<'db> Parameters<'db> {
         )
     }
 
-    fn apply_specialization(&mut self, db: &'db dyn Db, specialization: Specialization<'db>) {
-        self.value
-            .iter_mut()
-            .for_each(|param| param.apply_specialization(db, specialization));
+    fn apply_specialization(&self, db: &'db dyn Db, specialization: Specialization<'db>) -> Self {
+        Self {
+            value: self
+                .value
+                .iter()
+                .map(|param| param.apply_specialization(db, specialization))
+                .collect(),
+            is_gradual: self.is_gradual,
+        }
     }
 
     pub(crate) fn len(&self) -> usize {
@@ -1168,11 +1172,14 @@ impl<'db> Parameter<'db> {
         self
     }
 
-    fn apply_specialization(&mut self, db: &'db dyn Db, specialization: Specialization<'db>) {
-        self.annotated_type
-            .as_mut()
-            .map(|ty| *ty = ty.apply_specialization(db, specialization));
-        self.kind.apply_specialization(db, specialization);
+    fn apply_specialization(&self, db: &'db dyn Db, specialization: Specialization<'db>) -> Self {
+        Self {
+            annotated_type: self
+                .annotated_type
+                .map(|ty| ty.apply_specialization(db, specialization)),
+            kind: self.kind.apply_specialization(db, specialization),
+            form: self.form,
+        }
     }
 
     /// Strip information from the parameter so that two equivalent parameters compare equal.
@@ -1362,16 +1369,27 @@ pub(crate) enum ParameterKind<'db> {
 }
 
 impl<'db> ParameterKind<'db> {
-    fn apply_specialization(&mut self, db: &'db dyn Db, specialization: Specialization<'db>) {
+    fn apply_specialization(&self, db: &'db dyn Db, specialization: Specialization<'db>) -> Self {
         match self {
-            Self::PositionalOnly { default_type, .. }
-            | Self::PositionalOrKeyword { default_type, .. }
-            | Self::KeywordOnly { default_type, .. } => {
-                default_type
-                    .as_mut()
-                    .map(|ty| *ty = ty.apply_specialization(db, specialization));
-            }
-            Self::Variadic { .. } | Self::KeywordVariadic { .. } => {}
+            Self::PositionalOnly { default_type, name } => Self::PositionalOnly {
+                default_type: default_type
+                    .as_ref()
+                    .map(|ty| ty.apply_specialization(db, specialization)),
+                name: name.clone(),
+            },
+            Self::PositionalOrKeyword { default_type, name } => Self::PositionalOrKeyword {
+                default_type: default_type
+                    .as_ref()
+                    .map(|ty| ty.apply_specialization(db, specialization)),
+                name: name.clone(),
+            },
+            Self::KeywordOnly { default_type, name } => Self::KeywordOnly {
+                default_type: default_type
+                    .as_ref()
+                    .map(|ty| ty.apply_specialization(db, specialization)),
+                name: name.clone(),
+            },
+            Self::Variadic { .. } | Self::KeywordVariadic { .. } => self.clone(),
         }
     }
 }
@@ -1388,20 +1406,16 @@ mod tests {
     use super::*;
     use crate::db::tests::{setup_db, TestDb};
     use crate::symbol::global_symbol;
-    use crate::types::{FunctionLiteral, FunctionSignature, FunctionType, KnownClass};
+    use crate::types::{FunctionSignature, FunctionType, KnownClass};
     use ruff_db::system::DbWithWritableSystem as _;
 
     #[track_caller]
-    fn get_function_f<'db>(db: &'db TestDb, file: &'static str) -> FunctionLiteral<'db> {
+    fn get_function_f<'db>(db: &'db TestDb, file: &'static str) -> FunctionType<'db> {
         let module = ruff_db::files::system_path_to_file(db, file).unwrap();
-        let function = global_symbol(db, module, "f")
+        global_symbol(db, module, "f")
             .symbol
             .expect_type()
-            .expect_function_literal();
-        let FunctionType::FunctionLiteral(literal) = function else {
-            panic!("function should be a function literal");
-        };
-        literal
+            .expect_function_literal()
     }
 
     #[track_caller]
@@ -1639,6 +1653,9 @@ mod tests {
         let expected_sig = func.internal_signature(&db);
 
         // With no decorators, internal and external signature are the same
-        assert_eq!(func.signature(&db), FunctionSignature::Single(expected_sig));
+        assert_eq!(
+            func.signature(&db),
+            &FunctionSignature::Single(expected_sig)
+        );
     }
 }

crates/red_knot_python_semantic/src/types/unpacker.rs

@@ -18,22 +18,16 @@ use super::{TupleType, UnionType};
 /// Unpacks the value expression type to their respective targets.
 pub(crate) struct Unpacker<'db> {
     context: InferContext<'db>,
-    target_scope: ScopeId<'db>,
-    value_scope: ScopeId<'db>,
+    scope: ScopeId<'db>,
     targets: FxHashMap<ScopedExpressionId, Type<'db>>,
 }
 
 impl<'db> Unpacker<'db> {
-    pub(crate) fn new(
-        db: &'db dyn Db,
-        target_scope: ScopeId<'db>,
-        value_scope: ScopeId<'db>,
-    ) -> Self {
+    pub(crate) fn new(db: &'db dyn Db, scope: ScopeId<'db>) -> Self {
         Self {
-            context: InferContext::new(db, target_scope),
+            context: InferContext::new(db, scope),
             targets: FxHashMap::default(),
-            target_scope,
-            value_scope,
+            scope,
         }
     }
 
@@ -49,7 +43,7 @@ impl<'db> Unpacker<'db> {
         );
 
         let value_type = infer_expression_types(self.db(), value.expression())
-            .expression_type(value.scoped_expression_id(self.db(), self.value_scope));
+            .expression_type(value.scoped_expression_id(self.db(), self.scope));
 
         let value_type = match value.kind() {
             UnpackKind::Assign => {
@@ -85,10 +79,8 @@ impl<'db> Unpacker<'db> {
     ) {
         match target {
             ast::Expr::Name(_) | ast::Expr::Attribute(_) => {
-                self.targets.insert(
-                    target.scoped_expression_id(self.db(), self.target_scope),
-                    value_ty,
-                );
+                self.targets
+                    .insert(target.scoped_expression_id(self.db(), self.scope), value_ty);
             }
             ast::Expr::Starred(ast::ExprStarred { value, .. }) => {
                 self.unpack_inner(value, value_expr, value_ty);

crates/red_knot_python_semantic/src/unpack.rs

@@ -30,9 +30,7 @@ use crate::Db;
 pub(crate) struct Unpack<'db> {
     pub(crate) file: File,
 
-    pub(crate) value_file_scope: FileScopeId,
-
-    pub(crate) target_file_scope: FileScopeId,
+    pub(crate) file_scope: FileScopeId,
 
     /// The target expression that is being unpacked. For example, in `(a, b) = (1, 2)`, the target
     /// expression is `(a, b)`.
@@ -49,19 +47,9 @@ pub(crate) struct Unpack<'db> {
 }
 
 impl<'db> Unpack<'db> {
-    /// Returns the scope in which the unpack value expression belongs.
-    ///
-    /// The scope in which the target and value expression belongs to are usually the same
-    /// except in generator expressions and comprehensions (list/dict/set), where the value
-    /// expression of the first generator is evaluated in the outer scope, while the ones in the subsequent
-    /// generators are evaluated in the comprehension scope.
-    pub(crate) fn value_scope(self, db: &'db dyn Db) -> ScopeId<'db> {
-        self.value_file_scope(db).to_scope_id(db, self.file(db))
-    }
-
-    /// Returns the scope where the unpack target expression belongs to.
-    pub(crate) fn target_scope(self, db: &'db dyn Db) -> ScopeId<'db> {
-        self.target_file_scope(db).to_scope_id(db, self.file(db))
+    /// Returns the scope where the unpacking is happening.
+    pub(crate) fn scope(self, db: &'db dyn Db) -> ScopeId<'db> {
+        self.file_scope(db).to_scope_id(db, self.file(db))
     }
 
     /// Returns the range of the unpack target expression.

docs/requirements-insiders.txt

@@ -1,5 +1,5 @@
 PyYAML==6.0.2
-ruff==0.11.6
+ruff==0.9.10
 mkdocs==1.6.1
 mkdocs-material @ git+ssh://git@github.com/astral-sh/mkdocs-material-insiders.git@39da7a5e761410349e9a1b8abf593b0cdd5453ff
 mkdocs-redirects==1.2.2

docs/requirements.txt

@@ -1,5 +1,5 @@
 PyYAML==6.0.2
-ruff==0.11.6
+ruff==0.9.10
 mkdocs==1.6.1
 mkdocs-material==9.5.38
 mkdocs-redirects==1.2.2

knot.schema.json

@@ -460,16 +460,6 @@
             }
           ]
         },
-        "invalid-protocol": {
-          "title": "detects invalid protocol class definitions",
-          "description": "## What it does\nChecks for invalidly defined protocol classes.\n\n## Why is this bad?\nAn invalidly defined protocol class may lead to the type checker inferring\nunexpected things. It may also lead to `TypeError`s at runtime.\n\n## Examples\nA `Protocol` class cannot inherit from a non-`Protocol` class;\nthis raises a `TypeError` at runtime:\n\n```pycon\n>>> from typing import Protocol\n>>> class Foo(int, Protocol): ...\n...\nTraceback (most recent call last):\n  File \"<python-input-1>\", line 1, in <module>\n    class Foo(int, Protocol): ...\nTypeError: Protocols can only inherit from other protocols, got <class 'int'>\n```",
-          "default": "error",
-          "oneOf": [
-            {
-              "$ref": "#/definitions/Level"
-            }
-          ]
-        },
         "invalid-raise": {
           "title": "detects `raise` statements that raise invalid exceptions or use invalid causes",
           "description": "Checks for `raise` statements that raise non-exceptions or use invalid\ncauses for their raised exceptions.\n\n## Why is this bad?\nOnly subclasses or instances of `BaseException` can be raised.\nFor an exception's cause, the same rules apply, except that `None` is also\npermitted. Violating these rules results in a `TypeError` at runtime.\n\n## Examples\n```python\ndef f():\n    try:\n        something()\n    except NameError:\n        raise \"oops!\" from f\n\ndef g():\n    raise NotImplemented from 42\n```\n\nUse instead:\n```python\ndef f():\n    try:\n        something()\n    except NameError as e:\n        raise RuntimeError(\"oops!\") from e\n\ndef g():\n    raise NotImplementedError from None\n```\n\n## References\n- [Python documentation: The `raise` statement](https://docs.python.org/3/reference/simple_stmts.html#raise)\n- [Python documentation: Built-in Exceptions](https://docs.python.org/3/library/exceptions.html#built-in-exceptions)",