sanitize/tsan_interface.h is NOT modules friendly

[pinskia]

fowarded from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122344.

GCC's libstdc++'s memory includes sanitize/tsan_interface.h if thread sanitizer is turned on BUT if you use memory in a modules to export anything, GCC 15+ errors out due to TU-local entities being in use:

error: 'template<class _Tp> std::_Sp_atomic< <template-parameter-1-1> >::_Atomic_count::~_Atomic_count()' exposes TU-local entity '__tsan_mutex_not_static'
tsan_interface.h:50:23: note: '__tsan_mutex_not_static' declared with internal linkage
50 | static const unsigned __tsan_mutex_not_static = 1 << 8;

That is __tsan_mutex_not_static is not modules friendly.
None of the following are:

// Mutex has static storage duration and no-op constructor and destructor.
// This effectively makes tsan ignore destroy annotation.
static const unsigned __tsan_mutex_linker_init      = 1 << 0;
// Mutex is write reentrant.
static const unsigned __tsan_mutex_write_reentrant  = 1 << 1;
// Mutex is read reentrant.
static const unsigned __tsan_mutex_read_reentrant   = 1 << 2;
// Mutex does not have static storage duration, and must not be used after
// its destructor runs.  The opposite of __tsan_mutex_linker_init.
// If this flag is passed to __tsan_mutex_destroy, then the destruction
// is ignored unless this flag was previously set on the mutex.
static const unsigned __tsan_mutex_not_static       = 1 << 8;

These constants still are an issue:

llvm-project/compiler-rt/include/sanitizer/tsan_interface.h

Line 50 in 086666d

static const unsigned __tsan_mutex_not_static = 1 << 8;

[frederick-vs-ja]

Looks like that we should use inline variables here whenever supported.

[d7d1cd]

Is there a case where a variable in a header should be static rather than inline?

@pinskia @frederick-vs-ja

[d7d1cd]

PR created #166399