Percetto is using designated struct initializers, but those are not
supported in standard C++ before C++20, resulting in some compilation
warnings.
The previous fix for that was using a diagnostic valid for clang but not
for g++ resulting in another warning when building with g++:
-----------------------------------------------------------------------
In file included from ../monado/src/xrt/auxiliary/math/m_relation_history.cpp:19:
../monado/src/xrt/auxiliary/util/u_trace_marker.h:21:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas]
21 | #pragma GCC diagnostic ignored "-Wc99-designator"
| ^~~~~~~~~~~~~~~~~~
-----------------------------------------------------------------------
For GCC the diagnostics to disable is actually "-Wpedantic", as shown
below:
-----------------------------------------------------------------------
In file included from ../monado/src/xrt/auxiliary/util/u_trace_marker.h:25,
from ../monado/src/xrt/auxiliary/math/m_relation_history.cpp:19:
../external/percetto/src/percetto.h: In function ‘void percetto_event_with_args(percetto_category*, uint32_t, const char*, int32_t, const percetto_track*, int64_t, uint64_t)’:
../external/percetto/src/percetto.h:424:5: warning: C++ designated initializers only available with ‘-std=c++2a’ or ‘-std=gnu++2a’ [-Wpedantic]
424 | .track = track,
| ^
-----------------------------------------------------------------------
And for clang "-Wc++20-designator" should be slightly more accurate:
-----------------------------------------------------------------------
In file included from ../monado/src/xrt/auxiliary/util/u_trace_marker.h:29:
../external/percetto/src/percetto.h:424:5: warning: designated initializers are a C++20 extension [-Wc++20-designator]
.track = track,
^
-----------------------------------------------------------------------
Fix all the warnings by ignoring the right diagnostics depending on the
compiler, taking care of differentiating clang++ from g++ as they both
define __GNUC__.
