[Bug preprocessor/52998] New: caret and -ftrack-macro-expansion don't mix well

[Bug preprocessor/52998] New: caret and -ftrack-macro-expansion don't mix well

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

             Bug #: 52998
           Summary: caret and -ftrack-macro-expansion don't mix well
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: manu@gcc.gnu.org


With GCC 4.8 and -ftrack-macro-expansion, we get:

manuel@gcc12:~$ cat macro-caret.c
#define OPERATE(OPRD1, OPRT, OPRD2) \
  OPRD1 OPRT OPRD2;

#define SHIFTL(A,B) \
  OPERATE (A,<<,B)

#define MULT(A) \
  SHIFTL (A,1)

void
g ()
{
  MULT (1.0);// 1.0 << 1; <-- so this is an error.
}

manuel@gcc12:~$ ~/trunk/186353M/build/gcc/cc1plus macro-caret.c
-ftrack-macro-expansion
macro-caret.c:8:13: error: invalid operands of types ‘double’ and ‘int’ to
binary ‘operator<<’
   SHIFTL (A,1)
             ^
macro-caret.c:2:14: note: in expansion of macro 'OPERATE'
   OPRD1 OPRT OPRD2;
              ^
macro-caret.c:5:3: note: expanded from here
   OPERATE (A,<<,B)
   ^
macro-caret.c:5:17: note: in expansion of macro 'SHIFTL'
   OPERATE (A,<<,B)
                 ^
macro-caret.c:8:3: note: expanded from here
   SHIFTL (A,1)
   ^
macro-caret.c:8:13: note: in expansion of macro 'MULT'
   SHIFTL (A,1)
             ^
macro-caret.c:13:3: note: expanded from here
   MULT (1.0);// 1.0 << 1; <-- so this is an error.
   ^

And with GCC:

manuel@gcc12:~$ ~/trunk/186353M/build/gcc/cc1 macro-caret.c
-ftrack-macro-expansion
macro-caret.c: In function ‘g’:
macro-caret.c:5:14: error: invalid operands to binary << (have ‘double’ and
‘int’)
   OPERATE (A,<<,B)
              ^
macro-caret.c:2:9: note: in expansion of macro 'OPERATE'
   OPRD1 OPRT OPRD2;
         ^
macro-caret.c:5:3: note: expanded from here
   OPERATE (A,<<,B)
   ^
macro-caret.c:5:14: note: in expansion of macro 'SHIFTL'
   OPERATE (A,<<,B)
              ^
macro-caret.c:8:3: note: expanded from here
   SHIFTL (A,1)
   ^
macro-caret.c:8:3: note: in expansion of macro 'MULT'
   SHIFTL (A,1)
   ^
macro-caret.c:13:3: note: expanded from here
   MULT (1.0);// 1.0 << 1; <-- so this is an error.
   ^

Note that cc1plus prints the error at 8:13 and cc1 at 5:14. Without
-ftrac-macro-expansion, both give 13:3.

[Bug preprocessor/52998] caret and -ftrack-macro-expansion don't mix well

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
           Priority|P3                          |P4
                 CC|                            |dodji at gcc dot gnu.org
            Version|unknown                     |4.8.0

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-04-15 20:35:08 UTC ---
I think with and without macro expansion, the error should be given at 13:3,
and unwind from outermost to innermost. Innermost to outermost makes sense if
we show preprocessed lines:

macro-caret.c:5:14: error: invalid operands to binary << (have ‘double’ and
‘int’)
   1.0 << 1
       ^
macro-caret.c:2:9: note: in expansion of macro 'OPERATE' [with OPRD1=0.1,
OPRT=<<, OPRD2=1]
   OPRD1 OPRT OPRD2;
         ^
macro-caret.c:5:3: note: expanded from here
   OPERATE (1.0,<<,1)
   ^
macro-caret.c:5:14: note: in expansion of macro 'SHIFTL' [with A=1.0, B=1]
   OPERATE (A,<<,B)
              ^
macro-caret.c:8:3: note: expanded from here
   SHIFTL (1.0,1)
   ^
macro-caret.c:8:3: note: in expansion of macro 'MULT' [with A=1.0]
   SHIFTL (A,1)
   ^
macro-caret.c:13:3: note: expanded from here
   MULT (1.0);// 1.0 << 1; <-- so this is an error.


Otherwise, the error is shown at some code the user has not typed, and that
shows no obvious error (OPERATE (A,<<,B)) . Hence, the user has to read the
output once to find the source of the error (MULT), and then again to unwind
the macro expansion. In that case, it is better to go outermost to innermost,
so the user can follow the macro expansion as it occurs.

What do you think Dodji?

[Bug preprocessor/52998] caret and -ftrack-macro-expansion don't mix well

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

--- Comment #2 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-04-15 20:37:44 UTC ---
(In reply to comment #1)
> I think with and without macro expansion, the error should be given at 13:3,
> and unwind from outermost to innermost. Innermost to outermost makes sense if
> we show preprocessed lines:
> 
> macro-caret.c:5:14: error: invalid operands to binary << (have ‘double’ and
> ‘int’)
>    1.0 << 1
>        ^

But with preprocessed source lines, the best location is 5:14, because this way
the user can compare what is in that line with the preprocessed line shown by
GCC. So, in some sense, cc1 is right, and cc1plus is wrong.

[Bug preprocessor/52998] caret and -ftrack-macro-expansion don't mix well

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-04-24
     Ever Confirmed|0                           |1

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-04-24 04:36:42 UTC ---
Confirmed.

[Bug preprocessor/52998] different macro unwinder for C and C++ (-ftrack-macro-expansion)

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|caret and                   |different macro unwinder
                   |-ftrack-macro-expansion     |for C and C++
                   |don't mix well              |(-ftrack-macro-expansion)

--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-04-30 17:28:05 UTC ---
Just a note that the recent commits about tracking macro locations haven't
changed this issue.

I change the summary to reflect that this has nothing to do with caret
diagnostics, just that it becomes evident thanks to it.

[Bug preprocessor/52998] different macro unwinder for C and C++ (-ftrack-macro-expansion)

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52998

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
C++ and C match up in GCC 6+.