Re: [PATCH] AC_LANG_INT_SAVE: Modernize function declarators (C89 and above).

[Paul Eggert]

On 8/7/20 1:01 PM, Vincent Lefevre wrote:
The program
int main(void)
{
   return 0;
}

compiles fine with g++, even using "-std=c++17 -pedantic".

I expect the problem was with non-GNU C++ compilers, not with g++. However, I'm 
not the C++ guy so I'm the wrong person to ask about the details. You could 
write to Bruno Haible - I think he was the one preferring 'int main () ...'.