[Clang] Clang and GCC diverge on parsing `new (std::nothrow_t())`

[Xniao]

Description:

I'm seeking clarification on whether the following code is well-formed C++.
GCC accepts it, but Clang rejects it with:
error: cannot allocate function type 'std::nothrow_t ()' with new

Program

#include <new>

int main() {
    char* p = new (std::nothrow_t()) char[1];
    return 0;
}

Is this a parsing difference, or is one compiler incorrect?
Repro: https://godbolt.org/z/17zfedxds

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Jireh Guo (Xniao)

## Description: I'm seeking clarification on whether the following code is well-formed C++. GCC accepts it, but Clang rejects it with: `error: cannot allocate function type 'std::nothrow_t ()' with new`

Program

#include <new>

int main() {
    char* p = new (std::nothrow_t()) char[1];
    return 0;
}

Is this a parsing difference, or is one compiler incorrect?
Repro: https://godbolt.org/z/17zfedxds

[frederick-vs-ja]

I think GCC is wrong per [dcl.ambig.res]/2. MSVC and EDG also parse std::nothrow_t() inside the parentheses as a type-id.

[Xniao]

Thanks for the analysis and confirming the behavior.

For cross-linking purposes, the corresponding GCC bug report is: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121333

[AaronBallman]

GCC folks seem to agree: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121333#c3

So I think this issue can be closed as the question is resolved?