[Bug c++/56247] New: internal compiler error: in tsubst_copy, at cp/pt.c:12131

[Bug c++/56247] New: internal compiler error: in tsubst_copy, at cp/pt.c:12131

[dsagald8 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

             Bug #: 56247
           Summary: internal compiler error: in tsubst_copy, at
                    cp/pt.c:12131
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dsagald8@gmail.com


Created attachment 29392
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29392
Test case

ICE when the same member function pointer (to a base class's method) is used as
a template parameter from two different methods of the same templated child
class. What's a bit unusual here is that the bug is only triggered if the same
instantiation occurs in two different methods.

The reduced test case is short enough to include directly:

--------
struct Base {
    void method() {}
};  

typedef void (Base::*MemPtr)();

// Template with a member function pointer "non-type parameter".
template<MemPtr func>
struct Wrapper {};

template<class C>
struct Child : public Base {
    // Templated derived class instantiates the Wrapper with the same parameter
    // in two different virtual methods.
    void foo() { typedef Wrapper<&Base::method> W; }
    void bar() { typedef Wrapper<&Base::method> W; }
};

// Instantiate Child with some type. 
template class Child<int>;
--------

Here's the detailed gcc output:
% /usr/local/bin/g++47 -v -save-temps -c bugtest.cc
Using built-in specs.
COLLECT_GCC=/usr/local/bin/g++47
Target: x86_64-portbld-freebsd8.2
Configured with: ./../gcc-4.7-20120818/configure --disable-nls
--enable-languages=c,c++,objc,fortran --libdir=/usr/local/lib/gcc47
--libexecdir=/usr/local/libexec/gcc47 --program-suffix=47
--with-as=/usr/local/bin/as --with-gmp=/usr/local
--with-gxx-include-dir=/usr/local/lib/gcc47/include/c++/
--with-ld=/usr/local/bin/ld --with-libiconv-prefix=/usr/local
--with-pkgversion='FreeBSD Ports Collection' --with-system-zlib
--enable-languages=c,c++,objc,fortran,java --prefix=/usr/local
--mandir=/usr/local/man --infodir=/usr/local/info/gcc47
--build=x86_64-portbld-freebsd8.2
Thread model: posix
gcc version 4.7.2 20120818 (prerelease) (FreeBSD Ports Collection) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
 /usr/local/libexec/gcc47/gcc/x86_64-portbld-freebsd8.2/4.7.2/cc1plus -E -quiet
-v src/scratch/bugtest.cc -mtune=generic -march=x86-64 -fpch-preprocess -o
bugtest.ii
ignoring nonexistent directory
"/usr/local/lib/gcc47/gcc/x86_64-portbld-freebsd8.2/4.7.2/../../../../../x86_64-portbld-freebsd8.2/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc47/include/c++/
 /usr/local/lib/gcc47/include/c++//x86_64-portbld-freebsd8.2
 /usr/local/lib/gcc47/include/c++//backward
 /usr/local/lib/gcc47/gcc/x86_64-portbld-freebsd8.2/4.7.2/include
 /usr/local/include
 /usr/local/lib/gcc47/gcc/x86_64-portbld-freebsd8.2/4.7.2/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-c' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
 /usr/local/libexec/gcc47/gcc/x86_64-portbld-freebsd8.2/4.7.2/cc1plus
-fpreprocessed bugtest.ii -quiet -dumpbase bugtest.cc -mtune=generic
-march=x86-64 -auxbase bugtest -version -o bugtest.s
GNU C++ (FreeBSD Ports Collection) version 4.7.2 20120818 (prerelease)
(x86_64-portbld-freebsd8.2)
        compiled by GNU C version 4.7.2 20120818 (prerelease), GMP version
5.0.1, MPFR version 3.0.0, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (FreeBSD Ports Collection) version 4.7.2 20120818 (prerelease)
(x86_64-portbld-freebsd8.2)
        compiled by GNU C version 4.7.2 20120818 (prerelease), GMP version
5.0.1, MPFR version 3.0.0, MPC version 0.8.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 4c5936a9f1a6230b2e84e5f997572e48
src/scratch/bugtest.cc: In instantiation of 'void Child<C>::bar() [with C =
int]':
src/scratch/bugtest.cc:21:16:   required from here
src/scratch/bugtest.cc:17:49: internal compiler error: in tsubst_copy, at
cp/pt.c:12131
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-02-07
            Summary|internal compiler error: in |[4.6/4.7/4.8 Regression]
                   |tsubst_copy, at             |internal compiler error: in
                   |cp/pt.c:12131               |tsubst_copy, at
                   |                            |cp/pt.c:12131
     Ever Confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-02-07 23:44:56 UTC ---
Confirmed. 4.5.4 works for me.

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org
   Target Milestone|---                         |4.6.4

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-08 08:46:12 UTC ---
Started with http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149223

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

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

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

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

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

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

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-09 20:39:21 UTC ---
Author: jason
Date: Sat Feb  9 20:39:13 2013
New Revision: 195922

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195922
Log:
    PR c++/56247
    * pt.c (eq_specializations): Set comparing_specializations.
    * tree.c (cp_tree_equal): Check it.
    * cp-tree.h: Declare it.

Added:
    trunk/gcc/testsuite/g++.dg/template/ptrmem23.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/pt.c
    trunk/gcc/cp/tree.c

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-09 20:47:31 UTC ---
Author: jason
Date: Sat Feb  9 20:47:24 2013
New Revision: 195923

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195923
Log:
    PR c++/56247
    * pt.c (eq_specializations): Set comparing_specializations.
    * tree.c (cp_tree_equal): Check it.
    * cp-tree.h: Declare it.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/g++.dg/template/ptrmem23.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/cp-tree.h
    branches/gcc-4_7-branch/gcc/cp/pt.c
    branches/gcc-4_7-branch/gcc/cp/tree.c

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2013-02-09 20:54:05 UTC ---
Author: jason
Date: Sat Feb  9 20:53:59 2013
New Revision: 195924

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195924
Log:
    PR c++/56247
    * pt.c (eq_specializations): Set comparing_specializations.
    * tree.c (cp_tree_equal): Check it.
    * cp-tree.h: Declare it.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/g++.dg/template/ptrmem23.C
Modified:
    branches/gcc-4_6-branch/gcc/cp/ChangeLog
    branches/gcc-4_6-branch/gcc/cp/cp-tree.h
    branches/gcc-4_6-branch/gcc/cp/pt.c
    branches/gcc-4_6-branch/gcc/cp/tree.c

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-11 08:48:14 UTC ---
Fixed.

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[dsagald8 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

DS <dsagald8 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |VERIFIED

--- Comment #7 from DS <dsagald8 at gmail dot com> 2013-03-01 19:59:04 UTC ---
Awesome quick work. Very impressive -- thank you!

[Bug c++/56247] [4.6/4.7/4.8 Regression] internal compiler error: in tsubst_copy, at cp/pt.c:12131

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56247

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:f83adb68ed9cef1fbd4c16447eb4e89676df9f62

commit r10-7787-gf83adb68ed9cef1fbd4c16447eb4e89676df9f62
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat Apr 18 06:22:21 2020 -0400

    c++: spec_hasher::equal and PARM_DECLs [PR94632]

    In the testcase below, during specialization of c<int>::d, we build two
    identical specializations of the parameter type b<decltype(e)::k> -- one
when
    substituting into c<int>::d's TYPE_ARG_TYPES and another when substituting
into
    c<int>::d's DECL_ARGUMENTS.

    We don't reuse the first specialization the second time around as a
consequence
    of the fix for PR c++/56247 which made PARM_DECLs always compare different
from
    one another during spec_hasher::equal.  As a result, when looking up
existing
    specializations of 'b', spec_hasher::equal considers the template argument
    decltype(e')::k to be different from decltype(e'')::k, where e' and e'' are
the
    result of two calls to tsubst_copy on the PARM_DECL e.

    Since the two specializations are considered different due to the mentioned
fix,
    their TYPE_CANONICAL points to themselves even though they are otherwise
    identical types, and this triggers an ICE in
maybe_rebuild_function_decl_type
    when comparing the TYPE_ARG_TYPES of c<int>::d to its DECL_ARGUMENTS.

    This patch fixes this issue at the spec_hasher::equal level by ignoring the
    'comparing_specializations' flag in cp_tree_equal whenever the
DECL_CONTEXTs of
    the two parameters are identical.  This seems to be a sufficient condition
to be
    able to correctly compare PARM_DECLs structurally.  (This also subsumes the
    CONSTRAINT_VAR_P check since constraint variables all have empty, and
therefore
    identical, DECL_CONTEXTs.)

    gcc/cp/ChangeLog:

            PR c++/94632
            * tree.c (cp_tree_equal) <case PARM_DECL>: Ignore
            comparing_specializations if the parameters' contexts are
identical.

    gcc/testsuite/ChangeLog:

            PR c++/94632
            * g++.dg/template/canon-type-14.C: New test.