[Bug c++/94768] New: Wreturn-type should be error, not warning

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94768

            Bug ID: 94768
           Summary: Wreturn-type should be error, not warning
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

For this C++ code:

void g( int);

struct S
{
        int a;
        int b;

        S & operator = ( const S & that)
        {
                g( that.a);
        }
};

G++ produces only a warning, although it does give us a clue
what it is expecting:

$ /home/dcb/gcc/results/bin/gcc -c -g -O2 -Wall apr26d.cc
apr26d.cc: In member function ‘S& S::operator=(const S&)’:
apr26d.cc:12:2: warning: no return statement in function returning non-void
[-Wreturn-type]
   11 |   g( that.a);
  +++ |+  return *this;
   12 |  }
      |  ^
$ 

I have to add -Werror=return-type to get compilation to stop.

$ /home/dcb/gcc/results/bin/gcc -c -Werror=return-type apr26d.cc
apr26d.cc: In member function ‘S& S::operator=(const S&)’:
apr26d.cc:12:2: error: no return statement in function returning non-void
[-Werror=return-type]
   11 |   g( that.a);
  +++ |+  return *this;
   12 |  }
      |  ^
cc1plus: some warnings being treated as errors
$ 

I'll have a look at switching on Werror=return-type permanently locally.

IMHO, for a C++ function returning non-void, a complete absence of any return
statement in the function really should produce an error.

Yes a warning is a diagnostic and so conforms with ISO C++ rules,
but finding obvious bugs at compile time is preferable to runtime.