Silence two GCC warnings in Skia include files

Since 9c9a711ac5d8f32ac318d0e4ecab7b3a26bc2150 "Update skia to m111", various
versions of GCC produce

> In file included from workdir/UnpackedTarball/skia/include/gpu/GrRecordingContext.h:13,
>                  from workdir/UnpackedTarball/skia/include/gpu/GrDirectContext.h:11,
>                  from workdir/UnpackedTarball/skia/tools/sk_app/WindowContext.h:14,
>                  from vcl/inc/skia/utils.hxx:35,
>                  from vcl/skia/SkiaHelper.cxx:34:
> workdir/UnpackedTarball/skia/include/private/base/SkTArray.h:520:33: error: ‘cfi’ attribute directive ignored [-Werror=attributes]
>   520 |     static T* TCast(void* buffer) {
>       |                                 ^
> workdir/UnpackedTarball/skia/include/private/base/SkTArray.h: In constructor ‘SkSTArray<N, T, MEM_MOVE>::SkSTArray(std::initializer_list<_Up>)’:
> workdir/UnpackedTarball/skia/include/private/base/SkTArray.h:654:40: error: declaration of ‘data’ shadows a member of ‘SkSTArray<N, T, MEM_MOVE>’ [-Werror=shadow]
>   654 |     SkSTArray(std::initializer_list<T> data) : SkSTArray(data.begin(), SkToInt(data.size())) {}
>       |               ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
> workdir/UnpackedTarball/skia/include/private/base/SkTArray.h:684:22: note: shadowed declaration is here
>   684 |     using INHERITED::data;
>       |                      ^~~~

The -Werror=attributes is because GCC __attribute__((no_sanitize("...")))
accepts the same values as -fsanitize, but GCC doesn't support Clang's
-fsanitize=cfi.

The -Werror=shadow is because GCC is somewhat picky about uses of a name for a
variable when that name is also brought in by a using declaration from a
dependent base, as it /could/ be brought in as a variable (and not just as a
function, in which case there would normally be no such shadowing warning):

> $ cat test.cc
> template<typename> struct SkTArray { void data(); };
> template<typename T> struct SkSTArray: SkTArray<T> {
>     SkSTArray(int data) { (void) data; }
>     using SkTArray<T>::data;
> };
> $ g++ -Wshadow -fsyntax-only test.cc
> test.cc: In constructor ‘SkSTArray<T>::SkSTArray(int)’:
> test.cc:3:19: warning: declaration of ‘data’ shadows a member of ‘SkSTArray<T>’ [-Wshadow]
>     3 |     SkSTArray(int data) { (void) data; }
>       |               ~~~~^~~~
> test.cc:4:24: note: shadowed declaration is here
>     4 |     using SkTArray<T>::data;
>       |                        ^~~~

It feels more natural to silence these warnings at the site including the
relevant Skia include files, rather than as a patch to external/skia, as, at
least theoretically, we should also be able to build against a system's Skia
include files.

Change-Id: I0860b6a84e61da656038da8c77f3947d97ad8cf5
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/146364
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/vcl/inc/skia/utils.hxx b/vcl/inc/skia/utils.hxx
index 355718e8bfa1..3c19192e1c3a 100644
--- a/vcl/inc/skia/utils.hxx
+++ b/vcl/inc/skia/utils.hxx
@@ -32,7 +32,15 @@
 #include <premac.h>
 #include <SkRegion.h>
 #include <SkSurface.h>
+#if defined __GNUC__ && !defined __clang__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wattributes"
+#pragma GCC diagnostic ignored "-Wshadow"
+#endif
 #include <tools/sk_app/WindowContext.h>
+#if defined __GNUC__ && !defined __clang__
+#pragma GCC diagnostic pop
+#endif
 #include <postmac.h>
 
 #include <string_view>