[Bug c++/64356] New: Some constexpr expressions not recognized as constexpr

[Bug c++/64356] New: Some constexpr expressions not recognized as constexpr

[sneves at dei dot uc.pt]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64356

            Bug ID: 64356
           Summary: Some constexpr expressions not recognized as constexpr
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sneves at dei dot uc.pt

Consider the following snippet:

  template<size_t N>
  constexpr uint64_t f(const char (&x)[N]) {
    uint64_t s = 0;
  #if defined(FAILS)
    for(uint64_t c : x)
      s += c;
  #else
    for(size_t i = 0; i < N; ++i)
      s += x[i];
  #endif
    return s;
  }

  template<size_t N>
  constexpr uint64_t g(const char (&x)[N]) {
    char y[N] = {0};
    for(size_t i = 0; i < N; ++i)
      y[i] = x[i];
  #if defined(FAILS)
    return f(y);
  #else
    return f(x);
  #endif
  }

  constexpr auto x = g(__DATE__);

When FAILS is defined, GCC (trunk, 20141219) refuses to recognize x as a
constant expression, while with FAILS undefined it works as expected. Clang
accepts both variants.

[Bug c++/64356] Some constexpr expressions not recognized as constexpr

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64356

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-12
     Ever confirmed|0                           |1

[Bug c++/64356] Some constexpr expressions not recognized as constexpr

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64356

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

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

[Bug c++/64356] Some constexpr expressions not recognized as constexpr

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64356

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Tue Jan 13 21:04:43 2015
New Revision: 219559

URL: https://gcc.gnu.org/viewcvs?rev=219559&root=gcc&view=rev
Log:
    PR c++/64356
    PR libstdc++/58777
    * constexpr.c (cxx_eval_binary_expression): Don't VERIFY_CONSTANT
    pointer expressions.
    (cxx_eval_increment_expression): Likewise.

Added:
    trunk/gcc/testsuite/g++.dg/cpp1y/constexpr-local2.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/constexpr.c
    trunk/gcc/testsuite/g++.dg/cpp1y/pr63996.C
   
trunk/libstdc++-v3/testsuite/experimental/optional/constexpr/make_optional.cc
    trunk/libstdc++-v3/testsuite/experimental/optional/constexpr/observers/2.cc
    trunk/libstdc++-v3/testsuite/experimental/optional/constexpr/observers/3.cc

[Bug c++/64356] Some constexpr expressions not recognized as constexpr

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64356

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Thu Jan 15 20:46:09 2015
New Revision: 219687

URL: https://gcc.gnu.org/viewcvs?rev=219687&root=gcc&view=rev
Log:
    PR c++/64356
    * constexpr.c (cxx_eval_binary_expression): Fix pasto.

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/constexpr.c