[refurb] Do not emit diagnostic when loop variables are used outsid…

…e loop body (`FURB122`) (#15757)

Co-authored-by: Alex Waygood <[email protected]>

crates/ruff_linter/resources/test/fixtures/refurb/FURB122.py

@@ -2,57 +2,101 @@
 
 lines = ["line 1", "line 2", "line 3"]
 
+
 # Errors
 
-with open("file", "w") as f:
-    for line in lines:
-        f.write(line)
+def _():
+    with open("file", "w") as f:
+        for line in lines:
+            f.write(line)
 
-other_line = "other line"
-with Path("file").open("w") as f:
-    for line in lines:
-        f.write(other_line)
 
-with Path("file").open("w") as f:
-    for line in lines:
-        f.write(line)
+def _():
+    other_line = "other line"
+    with Path("file").open("w") as f:
+        for line in lines:
+            f.write(other_line)
 
-with Path("file").open("wb") as f:
-    for line in lines:
-        f.write(line.encode())
 
-with Path("file").open("w") as f:
-    for line in lines:
-        f.write(line.upper())
+def _():
+    with Path("file").open("w") as f:
+        for line in lines:
+            f.write(line)
 
-with Path("file").open("w") as f:
-    pass
 
-    for line in lines:
-        f.write(line)
+def _():
+    with Path("file").open("wb") as f:
+        for line in lines:
+            f.write(line.encode())
 
-# Offer unsafe fix if it would delete comments
-with open("file","w") as f:
-    for line in lines:
-        # a really important comment
-        f.write(line)
 
-# OK
+def _():
+    with Path("file").open("w") as f:
+        for line in lines:
+            f.write(line.upper())
 
-for line in lines:
-    Path("file").open("w").write(line)
 
-with Path("file").open("w") as f:
-    for line in lines:
+def _():
+    with Path("file").open("w") as f:
         pass
 
-        f.write(line)
+        for line in lines:
+            f.write(line)
+
+
+def _():
+    # Offer unsafe fix if it would delete comments
+    with open("file","w") as f:
+        for line in lines:
+            # a really important comment
+            f.write(line)
+
+
+def _():
+    with open("file", "w") as f:
+        for () in a:
+            f.write(())
+
+
+def _():
+    with open("file", "w") as f:
+        for a, b, c in d:
+            f.write((a, b))
+
+
+def _():
+    with open("file", "w") as f:
+        for [(), [a.b], (c,)] in d:
+            f.write(())
+
+
+def _():
+    with open("file", "w") as f:
+        for [([([a[b]],)],), [], (c[d],)] in e:
+            f.write(())
 
-with Path("file").open("w") as f:
+
+# OK
+
+def _():
     for line in lines:
-        f.write(line)
-    else:
-        pass
+        Path("file").open("w").write(line)
+
+
+def _():
+    with Path("file").open("w") as f:
+        for line in lines:
+            pass
+
+            f.write(line)
+
+
+def _():
+    with Path("file").open("w") as f:
+        for line in lines:
+            f.write(line)
+        else:
+            pass
 
 
 async def func():
@@ -61,6 +105,51 @@ async def func():
             f.write(line)
 
 
-with Path("file").open("w") as f:
-    for line in lines:
-        f.write()  # type: ignore
+def _():
+    with Path("file").open("w") as f:
+        for line in lines:
+            f.write()  # type: ignore
+
+
+def _():
+    with open("file", "w") as f:
+        global CURRENT_LINE
+        for CURRENT_LINE in lines:
+            f.write(CURRENT_LINE)
+
+
+def _():
+    foo = 1
+    def __():
+        with open("file", "w") as f:
+            nonlocal foo
+            for foo in lines:
+                f.write(foo)
+
+
+def _():
+    with open("file", "w") as f:
+        line = ''
+        for line in lines:
+            f.write(line)
+
+
+def _():
+    with open("file", "w") as f:
+        for a, b, c in d:
+            f.write((a, b))
+        print(a)
+
+
+def _():
+    with open("file", "w") as f:
+        for [*[*a]], b, [[c]] in d:
+            f.write((a, b))
+        print(c)
+
+
+def _():
+    with open("file", "w") as f:
+        global global_foo
+        for [a, b, (global_foo, c)] in d:
+            f.write((a, b))

crates/ruff_linter/src/checkers/ast/analyze/bindings.rs

@@ -5,7 +5,7 @@ use crate::checkers::ast::Checker;
 use crate::codes::Rule;
 use crate::rules::{
     flake8_import_conventions, flake8_pyi, flake8_pytest_style, flake8_type_checking, pyflakes,
-    pylint, ruff,
+    pylint, refurb, ruff,
 };
 
 /// Run lint rules over the [`Binding`]s.
@@ -22,6 +22,7 @@ pub(crate) fn bindings(checker: &mut Checker) {
         Rule::UnquotedTypeAlias,
         Rule::UsedDummyVariable,
         Rule::PytestUnittestRaisesAssertion,
+        Rule::ForLoopWrites,
     ]) {
         return;
     }
@@ -109,5 +110,10 @@ pub(crate) fn bindings(checker: &mut Checker) {
                 checker.diagnostics.push(diagnostic);
             }
         }
+        if checker.enabled(Rule::ForLoopWrites) {
+            if let Some(diagnostic) = refurb::rules::for_loop_writes_binding(checker, binding) {
+                checker.diagnostics.push(diagnostic);
+            }
+        }
     }
 }

crates/ruff_linter/src/checkers/ast/analyze/statement.rs

@@ -1415,7 +1415,7 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
                     refurb::rules::for_loop_set_mutations(checker, for_stmt);
                 }
                 if checker.enabled(Rule::ForLoopWrites) {
-                    refurb::rules::for_loop_writes(checker, for_stmt);
+                    refurb::rules::for_loop_writes_stmt(checker, for_stmt);
                 }
             }
             if checker.enabled(Rule::NeedlessElse) {