[Bug c++/96884] New: Missing diagnostics when applying the member operator on this in class template

[Bug c++/96884] New: Missing diagnostics when applying the member operator on this in class template

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96884

            Bug ID: 96884
           Summary: Missing diagnostics when applying the member operator
                    on this in class template
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anders.granlund.0 at gmail dot com
  Target Milestone: ---

Program (main.cpp):

  template<typename T>
  class V
  {
      int *a;
      void f()
      {
          this.a = 0;
      }
  };

  int main()
  {
  }

Compilation command line:

  g++ -std=c++17 -pedantic-errors main.cpp

Observed behaviour:

  No compilation errors.

Expected behaviour:

  Compilation error about incorrectly trying to use the member operator (.)
instead of (->) on the this keyword.

Note:

  clang++ gives the expected error message.

[Bug c++/96884] Missing diagnostics when applying the member operator on this in class template

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96884

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
We give an error when you actually call f in an instance of V:

96884.C: In instantiation of ‘void V<T>::f() [with T = int]’:
96884.C:14:9:   required from here
96884.C:7:16: error: request for member ‘a’ in ‘(V<int>*)this’, which is of
pointer type ‘V<int>*’ (maybe you meant to use ‘->’ ?)
    7 |           this.a = 0;
      |           ~~~~~^

which is OK.

[Bug c++/96884] Missing diagnostics when applying the member operator on this in class template

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96884

Anders Granlund <anders.granlund.0 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Anders Granlund <anders.granlund.0 at gmail dot com> ---
Yes. You are correct this is not a bug. The standard allows both possibilities
in this case.