[cfe-dev] GNU extensions - different behaviour of g++ and clang for taking address of temporary array

[Richard Smith via cfe-dev]

On 19 Feb 2018 10:31, "Aleksei Sidorin via cfe-dev" <cfe-dev at lists.llvm.org>
wrote:

Hi all,

Consider a test case:
#include <stdio.h>

typedef int a[];

void print(int *c) {
   printf("%d\n", c[0]);
}

int main() {
   print(a{2});
   return 0;
}

`g++ -std=gnu++11 -fsyntax-only` fails to compile this code: "error: taking
address of temporary array". However, clang accepts it without any warnings
and there is no any ASan output for it. Could someone explain me if it a
GCC or Clang issue?


It's a GCC bug -- this code is valid. The array to pointer conversion is
used to convert the int[1] temporary to a pointer; a reference is not bound
to it.

(GCC's behaviour is not unreasonable, though, and perhaps we should warn on
such constructs. I would imagine the GCC diagnostic would be suppressed by
making c a pointer to const int?)

-- 
Best regards,
Aleksei Sidorin,
SRR, Samsung Electronics


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