[`pyupgrade`] Do not offer fix when at least one target is `global`/`nonlocal` (`UP028`) (#16451)

## Summary

Resolves #16445.

`UP028` is now no longer always fixable: it will not offer a fix when at
least one `ExprName` target is bound to either a `global` or a
`nonlocal` declaration.

## Test Plan

`cargo nextest run` and `cargo insta test`.

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP028_0.py

@@ -163,3 +163,26 @@ def f():
         pass
     except Exception as x:
         pass
+
+
+# https://github.com/astral-sh/ruff/issues/15540
+def f():
+    for a in 1,:
+        yield a
+
+
+SOME_GLOBAL = None
+
+def f(iterable):
+    global SOME_GLOBAL
+
+    for SOME_GLOBAL in iterable:
+        yield SOME_GLOBAL
+
+    some_non_local = None
+
+    def g():
+        nonlocal some_non_local
+
+        for some_non_local in iterable:
+            yield some_non_local

crates/ruff_linter/resources/test/fixtures/pyupgrade/UP028_1.py

@@ -123,7 +123,20 @@ def f():
         yield x, y, x + y
 
 
-# https://github.com/astral-sh/ruff/issues/15540
 def f():
-    for a in 1,:
+    global some_global
-        yield a
+
+    for element in iterable:
+        some_global = element
+        yield some_global
+
+
+def f():
+    some_nonlocal = 1
+    
+    def g():
+        nonlocal some_nonlocal
+        
+        for element in iterable:
+            some_nonlocal = element
+            yield some_nonlocal

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

@@ -1,4 +1,4 @@
-use ruff_diagnostics::{AlwaysFixableViolation, Diagnostic, Edit, Fix};
+use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, ViolationMetadata};
 use ruff_python_ast::parenthesize::parenthesized_range;
 use ruff_python_ast::{self as ast, Expr, Stmt};
@@ -17,11 +17,19 @@ use crate::checkers::ast::Checker;
 /// ```python
 /// for x in foo:
 ///     yield x
+///
+/// global y
+/// for y in foo:
+///     yield y
 /// ```
 ///
 /// Use instead:
 /// ```python
 /// yield from foo
+///
+/// for _element in foo:
+///     y = _element
+///     yield y
 /// ```
 ///
 /// ## Fix safety
@@ -31,6 +39,9 @@ use crate::checkers::ast::Checker;
 /// to a `yield from` could lead to an attribute error if the underlying
 /// generator does not implement the `send` method.
 ///
+/// Additionally, if at least one target is `global` or `nonlocal`,
+/// no fix will be offered.
+///
 /// In most cases, however, the fix is safe, and such a modification should have
 /// no effect on the behavior of the program.
 ///
@@ -40,14 +51,16 @@ use crate::checkers::ast::Checker;
 #[derive(ViolationMetadata)]
 pub(crate) struct YieldInForLoop;
 
-impl AlwaysFixableViolation for YieldInForLoop {
+impl Violation for YieldInForLoop {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         "Replace `yield` over `for` loop with `yield from`".to_string()
     }
 
-    fn fix_title(&self) -> String {
+    fn fix_title(&self) -> Option<String> {
-        "Replace with `yield from`".to_string()
+        Some("Replace with `yield from`".to_string())
     }
 }
 
@@ -130,10 +143,22 @@ pub(crate) fn yield_in_for_loop(checker: &Checker, stmt_for: &ast::StmtFor) {
         format!("yield from {contents}")
     };
 
+    if !collect_names(value).any(|name| {
+        let semantic = checker.semantic();
+        let mut bindings = semantic.current_scope().get_all(name.id.as_str());
+
+        bindings.any(|id| {
+            let binding = semantic.binding(id);
+
+            binding.is_global() || binding.is_nonlocal()
+        })
+    }) {
         diagnostic.set_fix(Fix::unsafe_edit(Edit::range_replacement(
             contents,
             stmt_for.range(),
         )));
+    }
+
     checker.report_diagnostic(diagnostic);
 }
 

crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP028_0.py.snap

@@ -380,3 +380,46 @@ UP028_0.py:134:5: UP028 [*] Replace `yield` over `for` loop with `yield from`
 136 135 |     # Shadowing with multiple `except` blocks
 137 136 |     try:
 138 137 |         pass
+
+UP028_0.py:170:5: UP028 [*] Replace `yield` over `for` loop with `yield from`
+    |
+168 |   # https://github.com/astral-sh/ruff/issues/15540
+169 |   def f():
+170 | /     for a in 1,:
+171 | |         yield a
+    | |_______________^ UP028
+    |
+    = help: Replace with `yield from`
+
+ℹ Unsafe fix
+167 167 | 
+168 168 | # https://github.com/astral-sh/ruff/issues/15540
+169 169 | def f():
+170     |-    for a in 1,:
+171     |-        yield a
+    170 |+    yield from (1,)
+172 171 | 
+173 172 | 
+174 173 | SOME_GLOBAL = None
+
+UP028_0.py:179:5: UP028 Replace `yield` over `for` loop with `yield from`
+    |
+177 |       global SOME_GLOBAL
+178 |
+179 | /     for SOME_GLOBAL in iterable:
+180 | |         yield SOME_GLOBAL
+    | |_________________________^ UP028
+181 |
+182 |       some_non_local = None
+    |
+    = help: Replace with `yield from`
+
+UP028_0.py:187:9: UP028 Replace `yield` over `for` loop with `yield from`
+    |
+185 |           nonlocal some_non_local
+186 |
+187 | /         for some_non_local in iterable:
+188 | |             yield some_non_local
+    | |________________________________^ UP028
+    |
+    = help: Replace with `yield from`

crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__UP028_1.py.snap

@@ -1,20 +1,4 @@
 ---
 source: crates/ruff_linter/src/rules/pyupgrade/mod.rs
 ---
-UP028_1.py:128:5: UP028 [*] Replace `yield` over `for` loop with `yield from`
-    |
-126 |   # https://github.com/astral-sh/ruff/issues/15540
-127 |   def f():
-128 | /     for a in 1,:
-129 | |         yield a
-    | |_______________^ UP028
-    |
-    = help: Replace with `yield from`
 
-ℹ Unsafe fix
-125 125 | 
-126 126 | # https://github.com/astral-sh/ruff/issues/15540
-127 127 | def f():
-128     |-    for a in 1,:
-129     |-        yield a
-    128 |+    yield from (1,)