[libc++] Change workaround for init_priority((100)) outside of system headers
We had previously been using a different workaround for pretending that
we were inside a system header, however it had some undesirable effects
on dependency parsing for build systems, as explained in [1].
This patch changes the workaround to use `#pragma GCC system_header`,
which shouldn't suffer from the same issue. Unfortunately, it is a lot
more verbose. The issue is that `#pragma GCC system_header` is ignored
when we are inside a source file, so we have to create a header just for
the sake of using it. IMO this seems like an artificial restriction
without much benefit, but investigating that is a different story.
For now, this should at least solve build system problems at the
cost of some readability.
[1]: https://reviews.llvm.org/D95972#3178968
Differential Revision: https://reviews.llvm.org/D115334
NOKEYCHECK=True
GitOrigin-RevId: 515afe8b13a659a7a979280ed87891e74cc7915c
diff --git a/src/chrono.cpp b/src/chrono.cpp
index 8ff3faf..5aa7af7 100644
--- a/src/chrono.cpp
+++ b/src/chrono.cpp
@@ -80,9 +80,9 @@
GetSystemTimeAsFileTimePtr fp;
};
-# 83 "chrono.cpp" 1 3
-GetSystemTimeInit GetSystemTimeAsFileTimeFunc _LIBCPP_INIT_PRIORITY_MAX;
-# 85 "chrono.cpp" 2
+// Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
+// attribute with a value that's reserved for the implementation (we're the implementation).
+#include "chrono_system_time_init.h"
} // namespace
#endif