[PATCH 4/4] meson: warn on GCC < 12.0 due to lack of -ftrivial-auto-var-init=zero

["Daniel P. Berrangé" <berrange@redhat.com>]

The security policy for assigning CVEs has an assumption that all
stack variables are zero initialized. Our CLang min version gives
us -ftrivial-auto-var-init=zero, but that is only available in GCC
12 onwards.

Our min GCC is 10.4 but only NetBSD has such an old version.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 meson.build | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/meson.build b/meson.build
index 5315420a41..eeca8d074a 100644
--- a/meson.build
+++ b/meson.build
@@ -327,6 +327,12 @@ endif
 foreach lang : all_languages
   compiler = meson.get_compiler(lang)
   if compiler.get_id() == 'gcc' and compiler.version().version_compare('>=10.4')
+      if not compiler.version().version_compare('>=12.0')
+          warning('GCC < 12.0 does not support -ftrivial-auto-var-init=zero.')
+          warning('This compiler will not satisfy the QEMU security policy ')
+          warning('for assigning CVE which is predicated on zero-initialization ')
+          warning('of  stack variables. Update to GCC 12.0 or use CLang >= 17.0 ')
+      endif
     # ok
   elif compiler.get_id() == 'clang' and compiler.compiles('''
       #ifdef __apple_build_version__
-- 
2.55.0