Add support for the `counted_by` attribute

This is a new attribute released in GCC 15 and clang 18. It isn't
supported in C++ compilers at the moment.

4 files changed, 37 insertions, 6 deletions

diff --git a/docs/markdown/Reference-tables.md b/docs/markdown/Reference-tables.md
index 9ac24a43c..4a3bf288b 100644
--- a/docs/markdown/Reference-tables.md
+++ b/docs/markdown/Reference-tables.md
@@ -297,6 +297,7 @@ which are supported by GCC, Clang, and other compilers.
 | const                       |
 | constructor                 |
 | constructor_priority        |
+| counted_by⁸                 |
 | deprecated                  |
 | destructor                  |
 | error                       |
@@ -352,6 +353,8 @@ which are supported by GCC, Clang, and other compilers.
 
 ⁷ *New in 1.5.0*
 
+⁸ *New in 1.10.0*
+
 ### MSVC __declspec
 
 These values are supported using the MSVC style `__declspec` annotation,
diff --git a/docs/markdown/snippets/add_counted_by_attribute.md b/docs/markdown/snippets/add_counted_by_attribute.md
new file mode 100644
index 000000000..aa80b6dad
--- /dev/null
+++ b/docs/markdown/snippets/add_counted_by_attribute.md
@@ -0,0 +1,4 @@
+## Support for the `counted_by` attribute
+
+`compiler.has_function_attribute()` now supports for the new `counted_by`
+attribute.
diff --git a/mesonbuild/compilers/c_function_attributes.py b/mesonbuild/compilers/c_function_attributes.py
index 4c8aa7054..e425dbfa2 100644
--- a/mesonbuild/compilers/c_function_attributes.py
+++ b/mesonbuild/compilers/c_function_attributes.py
@@ -30,6 +30,13 @@ C_FUNC_ATTRIBUTES = {
         'int foo(void) __attribute__((constructor));',
     'constructor_priority':
         'int foo( void ) __attribute__((__constructor__(65535/2)));',
+    'counted_by':
+        '''
+        struct foo {
+            unsigned int count;
+            char bar[] __attribute__((counted_by(count)));
+        };
+        ''',
     'deprecated':
         'int foo(void) __attribute__((deprecated("")));',
     'destructor':
diff --git a/test cases/common/197 function attributes/meson.build b/test cases/common/197 function attributes/meson.build
index db7e3af32..a2dc5b76f 100644
--- a/test cases/common/197 function attributes/meson.build
+++ b/test cases/common/197 function attributes/meson.build
@@ -117,7 +117,16 @@ if ['gcc', 'intel'].contains(c.get_id())
   endif
 endif
 
+if c.get_id() == 'clang'
+  if c.version().version_compare('>= 18.0.0')
+    attributes += 'counted_by'
+  endif
+endif
+
 if c.get_id() == 'gcc'
+  if c.version().version_compare('>= 15.1')
+    attributes += 'counted_by'
+  endif
   if c.version().version_compare('>= 14.1')
     attributes += 'null_terminated_string_arg'
   endif
@@ -128,19 +137,27 @@ if get_option('mode') == 'single'
     x = c.has_function_attribute(a)
     expected_result = expected.get(a, expected_default)
     assert(x == expected_result, '@0@: @1@'.format(c.get_id(), a))
-    x = cpp.has_function_attribute(a)
-    assert(x == expected_result, '@0@: @1@'.format(cpp.get_id(), a))
+    # counted_by is not currently supported by GCC or clang on C++
+    if a != 'counted_by'
+      x = cpp.has_function_attribute(a)
+      assert(x == expected_result, '@0@: @1@'.format(cpp.get_id(), a))
+    endif
   endforeach
 else
-  multi_expected = []
+  multi_expected_c = []
+  multi_expected_cpp = []
   foreach a : attributes
     if expected.get(a, expected_default)
-      multi_expected += a
+      multi_expected_c += a
+      # counted_by is not currently supported by GCC or clang on C++
+      if a != 'counted_by'
+        multi_expected_cpp += a
+      endif
     endif
   endforeach
 
   multi_check = c.get_supported_function_attributes(attributes)
-  assert(multi_check == multi_expected, 'get_supported_function_arguments works (C)')
+  assert(multi_check == multi_expected_c, 'get_supported_function_arguments works (C)')
   multi_check = cpp.get_supported_function_attributes(attributes)
-  assert(multi_check == multi_expected, 'get_supported_function_arguments works (C++)')
+  assert(multi_check == multi_expected_cpp, 'get_supported_function_arguments works (C++)')
 endif