Mark UP043 fix unsafe when the type annotation contains any comments (#14458)

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP043.py

@@ -50,3 +50,10 @@ def func() -> Generator[str, None, None]:
 
 async def func() -> AsyncGenerator[str, None]:
     yield "hello"
+
+
+async def func() -> AsyncGenerator[  # type: ignore
+    str,
+    None
+]:
+    yield "hello"

crates/ruff_linter/src/rules/pyupgrade/rules/unnecessary_default_type_args.rs

@@ -1,4 +1,4 @@
-use ruff_diagnostics::{AlwaysFixableViolation, Diagnostic, Edit, Fix};
+use ruff_diagnostics::{AlwaysFixableViolation, Applicability, Diagnostic, Edit, Fix};
 use ruff_macros::{derive_message_formats, violation};
 use ruff_python_ast::{self as ast, Expr};
 use ruff_text_size::{Ranged, TextRange};
@@ -44,6 +44,9 @@ use crate::checkers::ast::Checker;
 ///     yield 42
 /// ```
 ///
+/// ## Fix safety
+/// This rule's fix is marked as safe, unless the type annotation contains comments.
+///
 /// ## References
 /// - [PEP 696 – Type Defaults for Type Parameters](https://peps.python.org/pep-0696/)
 /// - [Annotating generators and coroutines](https://docs.python.org/3/library/typing.html#annotating-generators-and-coroutines)
@@ -93,26 +96,39 @@ pub(crate) fn unnecessary_default_type_args(checker: &mut Checker, expr: &Expr)
     }
 
     let mut diagnostic = Diagnostic::new(UnnecessaryDefaultTypeArgs, expr.range());
-    diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
-        checker
-            .generator()
-            .expr(&Expr::Subscript(ast::ExprSubscript {
-                value: value.clone(),
-                slice: Box::new(if let [elt] = valid_elts.as_slice() {
-                    elt.clone()
-                } else {
-                    Expr::Tuple(ast::ExprTuple {
-                        elts: valid_elts,
-                        ctx: ast::ExprContext::Load,
-                        range: TextRange::default(),
-                        parenthesized: true,
-                    })
-                }),
-                ctx: ast::ExprContext::Load,
-                range: TextRange::default(),
-            })),
-        expr.range(),
-    )));
+
+    let applicability = if checker
+        .comment_ranges()
+        .has_comments(expr, checker.source())
+    {
+        Applicability::Unsafe
+    } else {
+        Applicability::Safe
+    };
+
+    diagnostic.set_fix(Fix::applicable_edit(
+        Edit::range_replacement(
+            checker
+                .generator()
+                .expr(&Expr::Subscript(ast::ExprSubscript {
+                    value: value.clone(),
+                    slice: Box::new(if let [elt] = valid_elts.as_slice() {
+                        elt.clone()
+                    } else {
+                        Expr::Tuple(ast::ExprTuple {
+                            elts: valid_elts,
+                            ctx: ast::ExprContext::Load,
+                            range: TextRange::default(),
+                            parenthesized: true,
+                        })
+                    }),
+                    ctx: ast::ExprContext::Load,
+                    range: TextRange::default(),
+                })),
+            expr.range(),
+        ),
+        applicability,
+    ));
     checker.diagnostics.push(diagnostic);
 }
 

crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP043.py.snap

@@ -108,3 +108,28 @@ UP043.py:51:21: UP043 [*] Unnecessary default type arguments
 51    |-async def func() -> AsyncGenerator[str, None]:
    51 |+async def func() -> AsyncGenerator[str]:
 52 52 |     yield "hello"
+53 53 | 
+54 54 | 
+
+UP043.py:55:21: UP043 [*] Unnecessary default type arguments
+   |
+55 |   async def func() -> AsyncGenerator[  # type: ignore
+   |  _____________________^
+56 | |     str,
+57 | |     None
+58 | | ]:
+   | |_^ UP043
+59 |       yield "hello"
+   |
+   = help: Remove default type arguments
+
+ℹ Unsafe fix
+52 52 |     yield "hello"
+53 53 | 
+54 54 | 
+55    |-async def func() -> AsyncGenerator[  # type: ignore
+56    |-    str,
+57    |-    None
+58    |-]:
+   55 |+async def func() -> AsyncGenerator[str]:
+59 56 |     yield "hello"