From 38de46ae3c53caebd2ec45dad64f21ba576943e9 Mon Sep 17 00:00:00 2001
From: Charlie Marsh <charlie.r.marsh@gmail.com>
Date: Wed, 25 Jan 2023 12:36:50 -0500
Subject: [PATCH] Treat Python 3.7 as minimum supported version (#2159)

---
 ruff.schema.json                                |  4 ----
 ruff_cli/src/main.rs                            |  2 +-
 src/checkers/ast.rs                             |  4 +++-
 .../rules/unnecessary_future_import.rs          |  9 ++-------
 src/settings/types.rs                           | 17 ++++++++---------
 5 files changed, 14 insertions(+), 22 deletions(-)

diff --git a/ruff.schema.json b/ruff.schema.json
index f991eca97d..6a469583a8 100644
--- a/ruff.schema.json
+++ b/ruff.schema.json
@@ -1138,10 +1138,6 @@
     "PythonVersion": {
       "type": "string",
       "enum": [
-        "py33",
-        "py34",
-        "py35",
-        "py36",
         "py37",
         "py38",
         "py39",
diff --git a/ruff_cli/src/main.rs b/ruff_cli/src/main.rs
index b32bf86dab..8d11d0b633 100644
--- a/ruff_cli/src/main.rs
+++ b/ruff_cli/src/main.rs
@@ -201,7 +201,7 @@ quoting the executed command, along with the relevant file contents and `pyproje
     if cache {
         // `--no-cache` doesn't respect code changes, and so is often confusing during
         // development.
-        warn_user_once!("debug build without --no-cache.");
+        warn_user_once!("Detected debug build without --no-cache.");
     }
 
     let printer = Printer::new(&format, &log_level, &autofix, &violations);
diff --git a/src/checkers/ast.rs b/src/checkers/ast.rs
index ae69abe53d..05c9aba168 100644
--- a/src/checkers/ast.rs
+++ b/src/checkers/ast.rs
@@ -1044,7 +1044,9 @@ where
                     }
                 }
 
-                if self.settings.rules.enabled(&Rule::UnnecessaryFutureImport) {
+                if self.settings.rules.enabled(&Rule::UnnecessaryFutureImport)
+                    && self.settings.target_version >= PythonVersion::Py37
+                {
                     if let Some("__future__") = module.as_deref() {
                         pyupgrade::rules::unnecessary_future_import(self, stmt, names);
                     }
diff --git a/src/rules/pyupgrade/rules/unnecessary_future_import.rs b/src/rules/pyupgrade/rules/unnecessary_future_import.rs
index 68d9fd4bb3..8507875ab4 100644
--- a/src/rules/pyupgrade/rules/unnecessary_future_import.rs
+++ b/src/rules/pyupgrade/rules/unnecessary_future_import.rs
@@ -6,7 +6,6 @@ use rustpython_parser::ast::Stmt;
 use crate::ast::types::Range;
 use crate::checkers::ast::Checker;
 use crate::registry::Diagnostic;
-use crate::settings::types::PythonVersion;
 use crate::{autofix, violations};
 
 const PY33_PLUS_REMOVE_FUTURES: &[&str] = &[
@@ -34,17 +33,13 @@ const PY37_PLUS_REMOVE_FUTURES: &[&str] = &[
 
 /// UP010
 pub fn unnecessary_future_import(checker: &mut Checker, stmt: &Stmt, names: &[Located<AliasData>]) {
-    let target_version = checker.settings.target_version;
-
     let mut unused_imports: Vec<&Alias> = vec![];
     for alias in names {
         if alias.node.asname.is_some() {
             continue;
         }
-        if (target_version >= PythonVersion::Py33
-            && PY33_PLUS_REMOVE_FUTURES.contains(&alias.node.name.as_str()))
-            || (target_version >= PythonVersion::Py37
-                && PY37_PLUS_REMOVE_FUTURES.contains(&alias.node.name.as_str()))
+        if PY33_PLUS_REMOVE_FUTURES.contains(&alias.node.name.as_str())
+            || PY37_PLUS_REMOVE_FUTURES.contains(&alias.node.name.as_str())
         {
             unused_imports.push(alias);
         }
diff --git a/src/settings/types.rs b/src/settings/types.rs
index 3041515c38..42db6ccbaf 100644
--- a/src/settings/types.rs
+++ b/src/settings/types.rs
@@ -11,19 +11,15 @@ use schemars::JsonSchema;
 use serde::{de, Deserialize, Deserializer, Serialize};
 
 use super::hashable::HashableHashSet;
-use crate::fs;
 use crate::registry::Rule;
 use crate::rule_selector::RuleSelector;
+use crate::{fs, warn_user_once};
 
 #[derive(
     Clone, Copy, Debug, PartialOrd, Ord, PartialEq, Eq, Serialize, Deserialize, Hash, JsonSchema,
 )]
 #[serde(rename_all = "lowercase")]
 pub enum PythonVersion {
-    Py33,
-    Py34,
-    Py35,
-    Py36,
     Py37,
     Py38,
     Py39,
@@ -36,10 +32,13 @@ impl FromStr for PythonVersion {
 
     fn from_str(string: &str) -> Result<Self, Self::Err> {
         match string {
-            "py33" => Ok(PythonVersion::Py33),
-            "py34" => Ok(PythonVersion::Py34),
-            "py35" => Ok(PythonVersion::Py35),
-            "py36" => Ok(PythonVersion::Py36),
+            "py33" | "py34" | "py35" | "py36" => {
+                warn_user_once!(
+                    "Specified a version below the minimum supported Python version. Defaulting \
+                     to Python 3.7."
+                );
+                Ok(PythonVersion::Py37)
+            }
             "py37" => Ok(PythonVersion::Py37),
             "py38" => Ok(PythonVersion::Py38),
             "py39" => Ok(PythonVersion::Py39),