[Bug c++/51489] New: constexpr not working consistently

[Bug c++/51489] New: constexpr not working consistently

[dave at boostpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51489

             Bug #: 51489
           Summary: constexpr not working consistently
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dave@boostpro.com


I think this is a bug, and the program should compile.

  struct array
  {
      constexpr array() :x(0) {}
      constexpr int const* begin() { return &x; }
      int x;
  };
  constexpr array aa;
  constexpr auto b = aa.begin();
  static_assert(b-b == 0, "compiles just fine");
  static_assert(aa.begin()-aa.begin() == 0, "compiler thinks it's not a
constant expression");

[Bug c++/51489] constexpr not working consistently

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51489

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-12-18
                 CC|                            |jason at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> 2011-12-18 06:27:49 UTC ---
Specifically, DR 1313 makes this a valid constant-expression.

[Bug c++/51489] constexpr not working consistently

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51489

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> 2011-12-19 05:57:58 UTC ---
Author: jason
Date: Mon Dec 19 05:57:52 2011
New Revision: 182470

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182470
Log:
    PR c++/51489
    * semantics.c (cxx_eval_outermost_constant_expr): Check for
    conversion from pointer to integer here.
    (cxx_eval_constant_expression) [NOP_EXPR]: Not here.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-ptrsub.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/51489] constexpr not working consistently

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51489

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.7.0

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2011-12-19 05:58:26 UTC ---
Fixed.