[Bug c++/51633] New: [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[Bug c++/51633] New: [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[reichelt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

             Bug #: 51633
           Summary: [c++0x] [4.6/4.7 Regression] ICE with invalid
                    constexpr constructor
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: reichelt@gcc.gnu.org


The following invalid code snippet triggers an ICE since GCC 4.6.0:

==========================
struct A
{
  ~A();
};

struct B
{
  A a;
  constexpr B() {}
};
==========================

bug.cc: In constructor 'constexpr B::B()':
bug.cc:9:18: internal compiler error: in
build_constexpr_constructor_member_initializers, at cp/semantics.c:5908
Please submit a full bug report, [etc.]

A slightly different code snippet triggers an ICE in a different place:

==========================
struct A
{
  constexpr A() {}
  ~A();
};

struct B
{
  A a;
  constexpr B() { return; }
};
==========================

bug.cc: In constructor 'constexpr B::B()':
bug.cc:10:27: internal compiler error: in build_data_member_initialization, at
cp/semantics.c:5782
Please submit a full bug report, [etc.]

This looks related to PR51612 where the ICE happens in the same place.

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[reichelt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

Volker Reichelt <reichelt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code
   Target Milestone|---                         |4.6.3

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-12-20 10:30:39 UTC ---
By the way, calling these issues "Regression" doesn't seem appropriate:
granted, 4.5 may have parsed some constrexpr usages, but didn't have any
semantics implemented, could very hardly fail.

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-12-30 06:20:47 UTC ---
(In reply to comment #1)
> By the way, calling these issues "Regression" doesn't seem appropriate:
> granted, 4.5 may have parsed some constrexpr usages, but didn't have any
> semantics implemented, could very hardly fail.

In the past we decided accepts invalid changing into an ICE is a regression
which is why this was considered a regression (I Can find the previous bug
reports that mention that).

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-01-01 13:54:44 UTC ---
Bah...

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

Dodji Seketeli <dodji at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-01-09
                 CC|                            |dodji at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |dodji at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #4 from Dodji Seketeli <dodji at gcc dot gnu.org> 2012-01-11 13:22:55 UTC ---
It seems to me that the first example might actually be considered as
valid.

One non-fully clear reason why it could have been considered invalid
in the first place is tat the constructor of B does not explicitly
initialize a.

But then A doesn't have any member.  So we can say in the end that "B
doesn't have any non-initialized member".  And that can be argued to
comply with this relevant pre-requisite for constexpr constructors in
[dcl.constexpr]/8:

    every non-static data member and base class sub-object shall be
    initialized

I have discussed this with Jason off-line and he seems to agree.

Thought anyone?

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2012-01-11 13:52:11 UTC ---
The testcase is valid because A's implicitly-declared default constructor is
constexpr.  We just need to fix build_constexpr_member_initializers to deal
with the trees that we get for B().

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

--- Comment #6 from Dodji Seketeli <dodji at gcc dot gnu.org> 2012-01-12 23:28:52 UTC ---
Author: dodji
Date: Thu Jan 12 23:28:46 2012
New Revision: 183144

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183144
Log:
PR c++/51633 - ICEs with constexpr constructor

gcc/cp/

    PR c++/51633
    * semantics.c (cp_parser_ctor_initializer_opt_and_function_body):
    Set the pointer to the last block of the constructor to the
    current statement.
    (build_constexpr_constructor_member_initializers): Get
    build_data_member_initialization a chance to deal with more
    statements before we choke.

gcc/testsuite/

    PR c++/51633
    * g++.dg/cpp0x/constexpr-diag4.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-diag4.C
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-diag5.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/parser.c
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/51633] [c++0x] [4.6/4.7 Regression] ICE with invalid constexpr constructor

[dodji at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51633

Dodji Seketeli <dodji at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #7 from Dodji Seketeli <dodji at gcc dot gnu.org> 2012-01-12 23:34:16 UTC ---
Should be fixed in trunk (4.7).