Update release notes and diagnostics for static local variables in extern inline functions

Author: Susikrishna

clang/docs/ReleaseNotes.rst

@@ -402,6 +402,10 @@ Improvements to Clang's diagnostics
 - Clang now emits a diagnostic in case `vector_size` or `ext_vector_type`
   attributes are used with a negative size (#GH165463).
 
+- Clang now emits an extension warning (`ExtWarn`) instead of a regular warning
+  for static local variables declared inside `extern inline` functions
+  (#GH39524).
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -6339,11 +6339,9 @@ def warn_c2y_compat_internal_in_extern_inline : Warning<
   "using static %select{function|variable}0 %1 in an inline function with "
   "external linkage is incompatible with standards before C2y">,
   InGroup<CPre2yCompat>, DefaultIgnore;
-def warn_static_local_in_extern_inline
-    : ExtWarn<"non-constant static local variable in inline function may be "
-              "different "
-              "in different files">,
-      InGroup<StaticLocalInInline>;
+def warn_static_local_in_extern_inline : ExtWarn<
+  "non-constant static local variable in inline function may be different "
+  "in different files">, InGroup<StaticLocalInInline>;
 def note_convert_inline_to_static : Note<
   "use 'static' to give inline function %0 internal linkage">;