meson: Move -fsanitize=undefined into normal configuraton

With 8e466dd092 and 23ef50ae2d, we disable function pointer
sanitization in CI because the qemu code base does not support it.
We must disable this for normal usage of --enable-ubsan as well,
so move it there.

Append options rather than prepend, since all of this requires
proper ordering of options.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20240813095216.306555-3-richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab-ci.d/buildtest.yml

@@ -436,9 +436,8 @@ clang-system:
     job: amd64-fedora-container
   variables:
     IMAGE: fedora
-    CONFIGURE_ARGS: --cc=clang --cxx=clang++
-      --extra-cflags=-fsanitize=undefined --extra-cflags=-fno-sanitize-recover=undefined
-      --extra-cflags=-fno-sanitize=function
+    CONFIGURE_ARGS: --cc=clang --cxx=clang++ --enable-ubsan
+      --extra-cflags=-fno-sanitize-recover=undefined
     TARGETS: alpha-softmmu arm-softmmu m68k-softmmu mips64-softmmu s390x-softmmu
     MAKE_CHECK_ARGS: check-qtest check-tcg
 
@@ -449,10 +448,9 @@ clang-user:
   timeout: 70m
   variables:
     IMAGE: debian-all-test-cross
-    CONFIGURE_ARGS: --cc=clang --cxx=clang++ --disable-system
+    CONFIGURE_ARGS: --cc=clang --cxx=clang++ --disable-system --enable-ubsan
       --target-list-exclude=alpha-linux-user,microblazeel-linux-user,aarch64_be-linux-user,i386-linux-user,m68k-linux-user,mipsn32el-linux-user,xtensaeb-linux-user
-      --extra-cflags=-fsanitize=undefined --extra-cflags=-fno-sanitize-recover=undefined
-      --extra-cflags=-fno-sanitize=function
+      --extra-cflags=-fno-sanitize-recover=undefined
     MAKE_CHECK_ARGS: check-unit check-tcg
 
 # Set LD_JOBS=1 because this requires LTO and ld consumes a large amount of memory.

meson.build

@@ -493,8 +493,15 @@ if get_option('ubsan')
   # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84285
   if cc.links('int main(int argc, char **argv) { return argc + 1; }',
               args: [qemu_ldflags, '-fsanitize=undefined'])
-    qemu_cflags = ['-fsanitize=undefined'] + qemu_cflags
-    qemu_ldflags = ['-fsanitize=undefined'] + qemu_ldflags
+    qemu_cflags += ['-fsanitize=undefined']
+    qemu_ldflags += ['-fsanitize=undefined']
+
+    # Suppress undefined behaviour from function call to mismatched type.
+    # In addition, tcg prologue does not emit function type prefix
+    # required by function call sanitizer.
+    if cc.has_argument('-fno-sanitize=function')
+      qemu_cflags += ['-fno-sanitize=function']
+    endif
   else
     error('Your compiler does not support -fsanitize=undefined')
   endif