Consider the following code:
#include <windows.h>
#include <TraceLoggingActivity.h>
#include <TraceLoggingProvider.h>
#include <winmeta.h>
TRACELOGGING_DEFINE_PROVIDER(
g_hMyComponentProvider,
"SimpleTraceLoggingProvider",
// {0205c616-cf97-5c11-9756-56a2cee02ca7}
(0x0205c616,0xcf97,0x5c11,0x97,0x56,0x56,0xa2,0xce,0xe0,0x2c,0xa7));
void test()
{
TraceLoggingFunction(g_hMyComponentProvider);
}
int main()
{
TraceLoggingRegister(g_hMyComponentProvider);
test();
TraceLoggingUnregister(g_hMyComponentProvider);
}
It compiles with MSVC, but clang-cl reports an error:
C:\Program Files (x86)\Windows Kits\10\\include\10.0.22621.0\\shared/TraceLoggingActivity.h(377,30): note: expanded from macro '_tlgThisFunctionName'
#define _tlgThisFunctionName __FUNCTION__
^
.\tl.cpp(14,5): error: cannot initialize an array element of type 'char' with an lvalue of type 'const char[5]'
TraceLoggingFunction(g_hMyComponentProvider);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The second commit is not needed to support above code, however, during isolated tests in ms_predefined_expr.cpp
I found that MSVC accepts code with constexpr, whereas clang-cl does not.
I see that in most places PredefinedExpr is supported in constant evaluation, so I didn't wrap my code with ``if(MicrosoftExt)``.
Reviewed By: cor3ntin
Differential Revision: https://reviews.llvm.org/D158591
Predefined identifiers like __FUNCTION__ are treated like string
literals in MSVC, which means they can be concatentated together with
an adjacent string literal. Clang now supports this behavior as well,
in Microsoft extensions mode.
Fixes https://github.com/llvm/llvm-project/issues/63563
Differential Revision: https://reviews.llvm.org/D153914
