[Bug c++/95473] New: GCC misses -Wnull-dereference warning in a simple code

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95473

            Bug ID: 95473
           Summary: GCC misses -Wnull-dereference warning in a simple code
           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: ---

$cat null_ref.cc
int main(){
    int &x1 = *(int *)nullptr; // null reference
    return 0;
}

GCC can not catch any warning when I use -Wnull-dereference option. 
I also try to add -O1~Os, but GCC still produces nothing.

While in clang

$clang++-trunk -Wnull-dereference null_ref.cc 
null_ref.cc:2:15: warning: binding dereferenced null pointer to reference has
undefined behavior [-Wnull-dereference]
    int &x1 = *(int *)nullptr; // null reference
              ^~~~~~~~~~~~~~~
1 warning generated.

$g++ --version
g++ (GCC) 11.0.0 20200526 (experimental)
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