MS compatibility: placement operator new[] falls back to operator new

[llvmbot]

Bugzilla Link	13164
Resolution	FIXED
Resolved on	May 29, 2013 20:57
Version	trunk
OS	All
Blocks	llvm/llvm-bugzilla-archive#13707
Reporter	LLVM Bugzilla Contributor
CC	@AaronBallman,@DougGregor,@tritao

Extended Description

MSVC 10 (and presumably the previous versions as well) will compile the following without errors

#include <stddef.h>
struct arbitrary_t {} arbitrary;
void * operator new(size_t size, arbitrary_t);

int main() {
    int * p = new(arbitrary) int[4];
}

On the other hand, clang will (correctly) report

test.cpp:7:15: error: no matching function for call to 'operator new[]'
    int * p = new(arbitrary) int[4];
              ^  ~~~~~~~~~~~

Unfortunately, the header in MS's WDK only contains the non-array version of operator new(std::size_t, std::nothrow), which prevents anything that depends on WDK from being buildable with clang.

[llvmbot]

Note that MSVC will diagnose when the operator new function is looked up directly:

int * p = (int*)::operator new[](sizeof(int), arbitrary);

error C2039: 'new[]' : is not a member of '`global namespace''

[llvmbot]

Fix (no tests, -fsyntax-only): avakar/clang@9f61719

[AaronBallman]

Fixed in r182905

[tritao]

mentioned in issue llvm/llvm-bugzilla-archive#13707