Merge branch 'ps/clang-w-glibc-2.43-and-_Generic'

Headers from glibc 2.43 when used with clang does not allow
disabling C11 language features, causing build failures..

* ps/clang-w-glibc-2.43-and-_Generic:
  build: tolerate use of _Generic from glibc 2.43 with Clang

Author: gitster

config.mak.dev

@@ -98,6 +98,13 @@ endif
 endif
 endif
 
+# glibc 2.43 headers unconditionally use _Generic even when we ask the
+# compiler to stick to -std=gnu99 and unlike GCC, clang lacks a
+# workaround to squelch warnings from system headers.
+ifneq ($(filter clang1,$(COMPILER_FEATURES)),)     # if we are using clang
+DEVELOPER_CFLAGS += -Wno-c11-extensions
+endif
+
 # https://bugzilla.redhat.com/show_bug.cgi?id=2075786
 ifneq ($(filter gcc12,$(COMPILER_FEATURES)),)
 DEVELOPER_CFLAGS += -Wno-error=stringop-overread

meson.build

@@ -866,6 +866,12 @@ if get_option('warning_level') in ['2','3', 'everything'] and compiler.get_argum
       libgit_c_args += cflag
     endif
   endforeach
+
+  # Clang generates warnings when compiling glibc 2.43 because of the use of
+  # _Generic.
+  if compiler.get_id() == 'clang'
+    libgit_c_args += '-Wno-c11-extensions'
+  endif
 endif
 
 if get_option('breaking_changes')