[Bug c++/95559] New: Compiling "{{}}" result is inconsistent in different versions

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95559

            Bug ID: 95559
           Summary: Compiling "{{}}" result is inconsistent in different
                    versions
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

This case test.cc

#include<iostream>
int main() {
    return {{}};
}

In the version of GCC 6.1 - 8.4, it's compiled ok.

But in GCC 6.1 lower and 8.4 higher version, for example, in GCC trunk

$g++-trunk test.cc 
test.cc: In function 'int main()':
test.cc:3:15: error: too many braces around scalar initializer for type 'int'
    3 |     int var = {{}};
      | 

I also compiled test.cc in recent released Clang, and they all accept "{{}}".

Should GCC compile "{{}}" fine also? I think this is a supported feature
according to https://en.cppreference.com/w/cpp/language/return.