From 1fbbf39334bfd12733e83a115b87c3ae0e3f2e3e Mon Sep 17 00:00:00 2001
From: Philip Chimento <philip.chimento@gmail.com>
Date: Wed, 5 Nov 2025 00:20:20 -0800
Subject: [PATCH] mkenums: Handle G_GNUC_FLAG_ENUM annotation

It can appear either after 'enum' or after the closing brace. Also handle
__attribute__((flag_enum)) and, for C++ code, [[gnu::flag_enum]] and
[[clang::flag_enum]] and various other spellings of those. If it is
present, mark the enum as a flags enum, the same as if we detected left
shifts in the values.
---
 gobject/glib-mkenums.in  | 28 +++++++++---
 gobject/tests/mkenums.py | 95 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+), 6 deletions(-)

diff --git a/gobject/glib-mkenums.in b/gobject/glib-mkenums.in
index 7e794e96d..f38871467 100755
--- a/gobject/glib-mkenums.in
+++ b/gobject/glib-mkenums.in
@@ -207,9 +207,17 @@ def parse_entries(file, file_name):
             else:
                 continue
 
-        m = re.match(r'\s*\}\s*(\w+)', line)
+        m = re.match(r'''\s*\}\s*
+            ((?:
+                G_GNUC_FLAG_ENUM|
+                \[\[(?:.+,)*(?:gnu|clang)::flag_enum(?:,[^\]]+)*\]\]|
+                __attribute__\(\((?:.+,)*(?:flag_enum|__flag_enum__)(?:,[^)]+)*\)\)
+            )\s*)?
+            (\w+)''', line, flags=re.X)
         if m:
-            enumname = m.group(1)
+            if m.group(1) is not None:
+                flags = 1
+            enumname = m.group(2)
             enumindex += 1
             return 1
 
@@ -519,7 +527,13 @@ def process_file(curfilename):
         if re.match(r'\s*typedef\s+enum.*;', line):
             continue
 
-        m = re.match(r'''\s*typedef\s+enum\s*[_A-Za-z]*[_A-Za-z0-9]*\s*
+        m = re.match(r'''\s*typedef\s+enum\s*
+               ((?:
+                 G_GNUC_FLAG_ENUM|
+                \[\[(?:.+,)*(?:gnu|clang)::flag_enum(?:,[^\]]+)*\]\]|
+                __attribute__\(\((?:.+,)*(?:flag_enum|__flag_enum__)(?:,[^)]+)*\)\)
+               )\s*)?
+               [_A-Za-z]*[_A-Za-z0-9]*\s*
                ({)?\s*
                (?:/\*<
                  (([^*]|\*(?!/))*)
@@ -527,8 +541,10 @@ def process_file(curfilename):
                \s*({)?''', line, flags=re.X)
         if m:
             groups = m.groups()
-            if len(groups) >= 2 and groups[1] is not None:
-                options = parse_trigraph(groups[1])
+            if len(groups) >= 1 and groups[0] is not None:
+                flags = 1
+            if len(groups) >= 3 and groups[2] is not None:
+                options = parse_trigraph(groups[2])
                 if 'skip' in options:
                     continue
                 enum_prefix = options.get('prefix', None)
@@ -556,7 +572,7 @@ def process_file(curfilename):
                     print_warning("lowercase_name is deprecated, use underscore_name")
 
             # Didn't have trailing '{' look on next lines
-            if groups[0] is None and (len(groups) < 4 or groups[3] is None):
+            if groups[1] is None and (len(groups) < 5 or groups[4] is None):
                 while True:
                     line = curfile.readline()
                     if not line:
diff --git a/gobject/tests/mkenums.py b/gobject/tests/mkenums.py
index 98004bef8..86dd7b260 100644
--- a/gobject/tests/mkenums.py
+++ b/gobject/tests/mkenums.py
@@ -710,6 +710,101 @@ comment: {standard_bottom_comment}
             "4",
         )
 
+    def test_flag_enum_annotation(self):
+        """Test use of G_GNUC_FLAG_ENUM"""
+        possible_spellings = [
+            "G_GNUC_FLAG_ENUM",
+            "__attribute__((flag_enum))",
+            "__attribute__((__flag_enum__))",
+            "__attribute__((flag_enum,deprecated))",
+            "__attribute__((deprecated,__flag_enum__))",
+            "[[gnu::flag_enum]]",
+            "[[clang::flag_enum]]",
+            "[[nodiscard,gnu::flag_enum]]",
+            "[[clang::flag_enum,nodiscard]]",
+        ]
+        for spelling in possible_spellings:
+            # Test attribute after closing brace
+            h_contents = (
+                """
+                typedef enum {
+                    SOME_FLAGS_ONE = (1 << 1),
+                } %s SomeFlags;
+                """
+                % spelling
+            )
+            result = self.runMkenumsWithHeader(h_contents)
+            self.assertEqual("", result.err)
+            self.assertSingleEnum(
+                result,
+                "SomeFlags",
+                "some_flags",
+                "SOME_FLAGS",
+                "FLAGS",
+                "SOME",
+                "",
+                "flags",
+                "Flags",
+                "FLAGS",
+                "SOME_FLAGS_ONE",
+                "one",
+                "2",
+            )
+
+            # Test attribute after enum keyword, with anonymous enum
+            h_contents = (
+                """
+                typedef enum %s {
+                    SOME_FLAGS_TWO = (1 << 2),
+                } SomeFlags;
+                """
+                % spelling
+            )
+            result = self.runMkenumsWithHeader(h_contents)
+            self.assertEqual("", result.err)
+            self.assertSingleEnum(
+                result,
+                "SomeFlags",
+                "some_flags",
+                "SOME_FLAGS",
+                "FLAGS",
+                "SOME",
+                "",
+                "flags",
+                "Flags",
+                "FLAGS",
+                "SOME_FLAGS_TWO",
+                "two",
+                "4",
+            )
+
+            # Test attribute after enum keyword, with named enum
+            h_contents = (
+                """
+                typedef enum %s _SomeFlags {
+                    SOME_FLAGS_THREE = (1 << 3),
+                } SomeFlags;
+                """
+                % spelling
+            )
+            result = self.runMkenumsWithHeader(h_contents)
+            self.assertEqual("", result.err)
+            self.assertSingleEnum(
+                result,
+                "SomeFlags",
+                "some_flags",
+                "SOME_FLAGS",
+                "FLAGS",
+                "SOME",
+                "",
+                "flags",
+                "Flags",
+                "FLAGS",
+                "SOME_FLAGS_THREE",
+                "three",
+                "8",
+            )
+
     def test_enum_symbolic_expression(self):
         """Test use of symbol in value expression."""
         h_contents = """