Add a no-parallel mode

crates/ruff/resources/test/fixtures/flake8_pyi/PYI011.pyi

@@ -61,3 +61,43 @@ def f22(
     x: complex = -42.5j  # Error PYI011 Only simple default values allowed for typed arguments
     + 4.3j,
 ) -> None: ...
+def f23(
+    x: bool = True,  # OK
+) -> None: ...
+def f24(
+    x: float = 3.14,  # OK
+) -> None: ...
+def f25(
+    x: float = -3.14,  # OK
+) -> None: ...
+def f26(
+    x: complex = -3.14j,  # OK
+) -> None: ...
+def f27(
+    x: complex = -3 - 3.14j,  # OK
+) -> None: ...
+def f28(
+    x: float = math.tau,  # OK
+) -> None: ...
+def f29(
+    x: float = math.inf,  # OK
+) -> None: ...
+def f30(
+    x: float = -math.inf,  # OK
+) -> None: ...
+def f31(
+    x: float = inf,  # Error PYI011 Only simple default values allowed for typed arguments
+) -> None: ...
+def f32(
+    x: float = np.inf,  # Error PYI011 Only simple default values allowed for typed arguments
+) -> None: ...
+def f33(
+    x: float = math.nan,  # OK
+) -> None: ...
+def f34(
+    x: float = -math.nan,  # Error PYI011 Only simple default values allowed for typed arguments
+) -> None: ...
+def f35(
+    x: complex = math.inf  # Error PYI011 Only simple default values allowed for typed arguments
+    + 1j,
+) -> None: ...

crates/ruff/src/rule_redirects.rs

@@ -18,7 +18,6 @@ static REDIRECTS: Lazy<HashMap<&'static str, &'static str>> = Lazy::new(|| {
         // The following are here because we don't yet have the many-to-one mapping enabled.
         ("SIM111", "SIM110"),
         // The following are deprecated.
-        ("C4", "C40"),
         ("C9", "C90"),
         ("T1", "T10"),
         ("T2", "T20"),

crates/ruff/src/rules/flake8_pyi/rules/simple_defaults.rs

@@ -28,6 +28,14 @@ impl Violation for ArgumentSimpleDefaults {
     }
 }
 
+const ALLOWED_MATH_ATTRIBUTES_IN_DEFAULTS: &[&[&str]] = &[
+    &["math", "inf"],
+    &["math", "nan"],
+    &["math", "e"],
+    &["math", "pi"],
+    &["math", "tau"],
+];
+
 const ALLOWED_ATTRIBUTES_IN_DEFAULTS: &[&[&str]] = &[
     &["sys", "stdin"],
     &["sys", "stdout"],
@@ -99,6 +107,21 @@ fn is_valid_default_value_with_annotation(default: &Expr, checker: &Checker) ->
                     return checker.locator.slice(operand).len() <= 10;
                 }
             }
+            // Ex) `-math.inf`, `-math.pi`, etc.
+            if let ExprKind::Attribute { .. } = &operand.node {
+                if checker
+                    .ctx
+                    .resolve_call_path(default)
+                    .map_or(false, |call_path| {
+                        ALLOWED_MATH_ATTRIBUTES_IN_DEFAULTS.iter().any(|target| {
+                            // reject `-math.nan`
+                            call_path.as_slice() == *target && *target != ["math", "nan"]
+                        })
+                    })
+                {
+                    return true;
+                }
+            }
         }
         ExprKind::BinOp {
             left,
@@ -134,14 +157,15 @@ fn is_valid_default_value_with_annotation(default: &Expr, checker: &Checker) ->
                 }
             }
         }
-        // Ex) `sys.stdin`, etc.
+        // Ex) `math.inf`, `sys.stdin`, etc.
         ExprKind::Attribute { .. } => {
             if checker
                 .ctx
                 .resolve_call_path(default)
                 .map_or(false, |call_path| {
-                    ALLOWED_ATTRIBUTES_IN_DEFAULTS
+                    ALLOWED_MATH_ATTRIBUTES_IN_DEFAULTS
                         .iter()
+                        .chain(ALLOWED_ATTRIBUTES_IN_DEFAULTS.iter())
                         .any(|target| call_path.as_slice() == *target)
                 })
             {

crates/ruff/src/rules/flake8_pyi/snapshots/ruff__rules__flake8_pyi__tests__PYI011_PYI011.pyi.snap

@@ -145,4 +145,108 @@ expression: diagnostics
     column: 10
   fix: ~
   parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 80
+    column: 15
+  end_location:
+    row: 80
+    column: 23
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 83
+    column: 15
+  end_location:
+    row: 83
+    column: 23
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 86
+    column: 15
+  end_location:
+    row: 86
+    column: 24
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 89
+    column: 15
+  end_location:
+    row: 89
+    column: 18
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 92
+    column: 15
+  end_location:
+    row: 92
+    column: 21
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 95
+    column: 15
+  end_location:
+    row: 95
+    column: 23
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 98
+    column: 15
+  end_location:
+    row: 98
+    column: 24
+  fix: ~
+  parent: ~
+- kind:
+    name: TypedArgumentSimpleDefaults
+    body: Only simple default values allowed for typed arguments
+    suggestion: ~
+    fixable: false
+  location:
+    row: 101
+    column: 17
+  end_location:
+    row: 102
+    column: 8
+  fix: ~
+  parent: ~
 

crates/ruff_cli/src/args.rs

@@ -95,6 +95,9 @@ pub struct CheckArgs {
     /// Ignore any `# noqa` comments.
     #[arg(long)]
     ignore_noqa: bool,
+    /// Run in a single thread, rather than using all available cores.
+    #[clap(long, hide = true)]
+    no_parallel: bool,
     /// Output serialization format for violations.
     #[arg(long, value_enum, env = "RUFF_FORMAT")]
     pub format: Option<SerializationFormat>,
@@ -267,6 +270,7 @@ pub struct CheckArgs {
         conflicts_with = "show_settings",
         // Unsupported default-command arguments.
         conflicts_with = "ignore_noqa",
+        conflicts_with = "no_parallel",
         conflicts_with = "statistics",
         conflicts_with = "stdin_filename",
         conflicts_with = "watch",
@@ -282,6 +286,7 @@ pub struct CheckArgs {
         conflicts_with = "show_settings",
         // Unsupported default-command arguments.
         conflicts_with = "ignore_noqa",
+        conflicts_with = "no_parallel",
         conflicts_with = "statistics",
         conflicts_with = "stdin_filename",
         conflicts_with = "watch",
@@ -296,6 +301,7 @@ pub struct CheckArgs {
         // conflicts_with = "show_settings",
         // Unsupported default-command arguments.
         conflicts_with = "ignore_noqa",
+        conflicts_with = "no_parallel",
         conflicts_with = "statistics",
         conflicts_with = "stdin_filename",
         conflicts_with = "watch",
@@ -371,6 +377,7 @@ impl CheckArgs {
                 ignore_noqa: self.ignore_noqa,
                 isolated: self.isolated,
                 no_cache: self.no_cache,
+                no_parallel: self.no_parallel,
                 show_files: self.show_files,
                 show_settings: self.show_settings,
                 statistics: self.statistics,
@@ -435,6 +442,7 @@ pub struct Arguments {
     pub ignore_noqa: bool,
     pub isolated: bool,
     pub no_cache: bool,
+    pub no_parallel: bool,
     pub show_files: bool,
     pub show_settings: bool,
     pub statistics: bool,

crates/ruff_cli/src/lib.rs

@@ -140,6 +140,7 @@ fn check(args: CheckArgs, log_level: LogLevel) -> Result<ExitStatus> {
     };
     let cache = !cli.no_cache;
     let noqa = !cli.ignore_noqa;
+    let parallel = !cli.no_parallel;
     let mut printer_flags = PrinterFlags::empty();
     if !(cli.diff || fix_only) {
         printer_flags |= PrinterFlags::SHOW_VIOLATIONS;
@@ -155,6 +156,14 @@ fn check(args: CheckArgs, log_level: LogLevel) -> Result<ExitStatus> {
         warn_user_once!("Detected debug build without --no-cache.");
     }
 
+    if !parallel {
+        // If we're not running in parallel, we need to set up a single-threaded
+        // executor.
+        rayon::ThreadPoolBuilder::new()
+            .num_threads(1)
+            .build_global()?;
+    }
+
     if cli.add_noqa {
         if !matches!(autofix, fix::FixMode::None) {
             warn_user_once!("--fix is incompatible with --add-noqa.");