[PATCH 1/4] meson: hide tsan related warnings

[Pierrick Bouvier]

When building with gcc-12 -fsanitize=thread, gcc reports some
constructions not supported with tsan.
Found on debian stable.

qemu/include/qemu/atomic.h:36:52: error: ‘atomic_thread_fence’ is not supported 
with ‘-fsanitize=thread’ [-Werror=tsan]
   36 | #define smp_mb()                     ({ barrier(); 
__atomic_thread_fence(__ATOMIC_SEQ_CST); })
      |                                                    
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
---
 meson.build | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index c2a050b8443..899660ef020 100644
--- a/meson.build
+++ b/meson.build
@@ -499,7 +499,15 @@ if get_option('tsan')
                          prefix: '#include <sanitizer/tsan_interface.h>')
     error('Cannot enable TSAN due to missing fiber annotation interface')
   endif
-  qemu_cflags = ['-fsanitize=thread'] + qemu_cflags
+  tsan_warn_suppress = []
+  # gcc (>=11) will report constructions not supported by tsan:
+  # "error: ‘atomic_thread_fence’ is not supported with ‘-fsanitize=thread’"
+  # https://gcc.gnu.org/gcc-11/changes.html
+  # However, clang does not support this warning and this triggers an error.
+  if cc.has_argument('-Wno-tsan')
+    tsan_warn_suppress = ['-Wno-tsan']
+  endif
+  qemu_cflags = ['-fsanitize=thread'] + tsan_warn_suppress + qemu_cflags
   qemu_ldflags = ['-fsanitize=thread'] + qemu_ldflags
 endif
 
-- 
2.39.2