[Bug c++/95639] New: wrong error location

[Bug c++/95639] New: wrong error location

[f.heckenbach@fh-soft.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95639

            Bug ID: 95639
           Summary: wrong error location
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: f.heckenbach@fh-soft.de
  Target Milestone: ---

This may be similar to #93979, but I'm not sure.

% cat test.cpp
#define S(A) sizeof (A)

int main ()
{
  int a[10];
  return (int) S (a);
}
% g++ -Wold-style-cast test.cpp
t.cpp: In function 'int main()':
t.cpp:1:23: warning: use of old-style cast to 'int' [-Wold-style-cast]
    1 | #define S(A) sizeof (A)
      |                       ^
t.cpp:6:16: note: in expansion of macro 'S'
    6 |   return (int) S (a);
      |                ^

The warning itself is correct, but the location and the note point at the
macro, while the offending cast is in main.

[Bug c++/95639] wrong error location

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95639

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |mpolacek at gcc dot gnu.org
   Last reconfirmed|                            |2020-06-11

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.

[Bug c++/95639] wrong error location

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95639

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
With a trivial patch we generate:

95639.C: In function ‘int main()’:
95639.C:6:14: warning: use of old-style cast to ‘int’ [-Wold-style-cast]
    6 |   return (int) S (a);
      |              ^
      |          -----
      |          static_cast<int> ()


I suspect that's much better.

[Bug c++/95639] wrong error location

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95639

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|mpolacek at gcc dot gnu.org        |unassigned at gcc dot gnu.org

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Not that trivial because it breaks -fdiagnostics-generate-patch.

[Bug c++/95639] wrong error location

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95639

Eric Gallager <egallager at gcc dot gnu.org> changed:

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

--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #2)
> With a trivial patch we generate:
> 
> 95639.C: In function ‘int main()’:
> 95639.C:6:14: warning: use of old-style cast to ‘int’ [-Wold-style-cast]
>     6 |   return (int) S (a);
>       |              ^
>       |          -----
>       |          static_cast<int> ()
> 
> 
> I suspect that's much better.

(In reply to Marek Polacek from comment #3)
> Not that trivial because it breaks -fdiagnostics-generate-patch.

Could you post the patch anyways so we can figure out how to fix it?