gh-159336: Accept GCC warnings without an option suffix

Lib/test/test_tools/test_check_warnings.py

@@ -0,0 +1,29 @@
+import importlib
+import unittest
+
+from test.test_tools import imports_under_tool, skip_if_missing
+
+
+skip_if_missing("build")
+with imports_under_tool("build"):
+    check_warnings = importlib.import_module("check_warnings")
+
+
+class CheckWarningsTests(unittest.TestCase):
+    def test_warning_options(self):
+        for compiler, suffix, option in (
+            ("gcc", "", ""),
+            ("gcc", " [-Wunused-variable]", "-Wunused-variable"),
+            ("clang", " [-Wunused-variable]", "-Wunused-variable"),
+        ):
+            with self.subTest(compiler=compiler, suffix=suffix):
+                warnings = check_warnings.extract_warnings_from_compiler_output(
+                    "source.c:1:2: warning: example" + suffix, compiler)
+                self.assertEqual(warnings, [{
+                    "file": "source.c", "line": "1", "column": "2",
+                    "message": "example", "option": option,
+                }])
+
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Tools-Demos/2026-10-13-20-08-28.gh-issue-159336.wGccOp.rst

@@ -0,0 +1,2 @@
+Fix ``Tools/build/check_warnings.py`` to accept GCC diagnostics that
+omit the warning-option suffix.

Tools/build/check_warnings.py

@@ -100,7 +100,9 @@ def extract_warnings_from_compiler_output(
                     "line": match.group("line"),
                     "column": match.group("column"),
                     "message": match.group("message"),
-                    "option": match.group("option").lstrip("[").rstrip("]"),
+                    "option": (match.group("option") or "")
+                    .lstrip("[")
+                    .rstrip("]"),
                 })
             except AttributeError:
                 print(