[Bug c++/50059] New: [C++0x] Broken error message with __builtin_remquo & constexpr

[Bug c++/50059] New: [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

             Bug #: 50059
           Summary: [C++0x] Broken error message with __builtin_remquo &
                    constexpr
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: paolo.carlini@oracle.com


Consider this:

int r = 0;
constexpr double d = __builtin_remquo(1, 1, &r);

The error message is:

a.cc:2:49: error: expression ‘(r <unknown operator> 1)’ is not a
constant-expression

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-12 14:49:27 UTC ---
__builtin_modf has similar problems

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-08-12
                 CC|                            |jason at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-12 15:06:49 UTC ---
Happens also with <cmath> and std::remquo, std::modf, CC-ing Jason.

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-12 16:21:08 UTC ---
... and __builtin_frexp (std::frexp)

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-12 18:01:43 UTC ---
And I suspect that this diagnostic issue may be not unrelated to what I was
noticing today together with PR50060: these badly printed intrinsics (remquo,
modf, frexp) can be optimized by the middle-end but aren't really viable as
constexpr functions because of the pointer parameter. Thus, by the time error.c
is involved the middle-end has computed the constants and erased any info about
the name of the intrinsics. Can be?

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-13 20:03:26 UTC ---
Author: jason
Date: Sat Aug 13 20:03:23 2011
New Revision: 177735

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=177735
Log:
    PR c++/50059
    * error.c (dump_expr): Handle MODIFY_EXPR properly.

Added:
    trunk/gcc/testsuite/g++.dg/diagnostic/expr1.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/error.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
         AssignedTo|unassigned at gcc dot       |jason at redhat dot com
                   |gnu.org                     |
   Target Milestone|---                         |4.7.0

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2011-08-13 20:13:40 UTC ---
Fixed to print (r = 0) instead.  Anything further would need to change the
front end to delay folding like the C front end does.

[Bug c++/50059] [C++0x] Broken error message with __builtin_remquo & constexpr

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50059

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-13 21:33:52 UTC ---
Ah, thanks also for the clarification. Anyway, at least now the error message
makes clear why *exactly* the functions isn't viable as constexpr.