[Bug c++/52830] New: ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[Bug c++/52830] New: ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[lucdanton at free dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

             Bug #: 52830
           Summary: ICE: "canonical types differ for identity types ..."
                    when attempting SFINAE with member type
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: lucdanton@free.fr


Created attachment 27061
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27061
Testcase

Using

$ gcc-snapshot --version
gcc-snapshot (Debian 20120313-1) 4.8.0 20120313 (experimental) [trunk revision
185345]

I get the following when attempting to compile what I believe to be a correct
testcase program (although I could be wrong on correctness):

main.cpp:25:21: internal compiler error: canonical types differ for identical
types std::enable_if<std::is_same<typename foo<T>::type, U>::value, int> and
std::enable_if<std::is_same<T, U>::value, int>

The program compiles and behaves as expected if T is used instead of
type/typename foo<T>::type in both declaration and definition, or if bar is
defined inline.

[Bug c++/52830] ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-05-30
     Ever confirmed|0                           |1

[Bug c++/52830] ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[patrick.a.moran at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Patrick Moran <patrick.a.moran at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |patrick.a.moran at gmail dot com

--- Comment #1 from Patrick Moran <patrick.a.moran at gmail dot com> ---
Created attachment 32992
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32992&action=edit
Another reproduction

Adding my reproducing test case from a duplicate bug I filed before I mark it a
duplicate (the failure behavior is different on 4.9.0 than from snapshot, but
I've confirmed it's the same issue).

[Bug c++/52830] ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[patrick.a.moran at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

--- Comment #2 from Patrick Moran <patrick.a.moran at gmail dot com> ---
*** Bug 61370 has been marked as a duplicate of this bug. ***

[Bug c++/52830] ICE: "canonical types differ for identity types ..." when attempting SFINAE with member type

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

--- Comment #4 from David Binderman <dcb314 at hotmail dot com> ---
Created attachment 35426
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35426&action=edit
gzipped C++ source code

gcc trunk dated 20150427 ices in the same way on the attached code.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:a210d404d08e363af4b2e2a60986c3cb08f8ebc5

commit r11-4890-ga210d404d08e363af4b2e2a60986c3cb08f8ebc5
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Nov 10 14:57:19 2020 -0500

    c++: Add 5 unfixed tests.

    A couple of dg-ice tests.

    gcc/testsuite/ChangeLog:

            PR c++/52830
            PR c++/88982
            PR c++/90799
            PR c++/87765
            PR c++/89565
            * g++.dg/cpp0x/constexpr-52830.C: New test.
            * g++.dg/cpp0x/vt-88982.C: New test.
            * g++.dg/cpp1z/class-deduction76.C: New test.
            * g++.dg/cpp1z/constexpr-lambda26.C: New test.
            * g++.dg/cpp2a/nontype-class39.C: New test.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Alex Coplan <acoplan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |acoplan at gcc dot gnu.org

--- Comment #8 from Alex Coplan <acoplan at gcc dot gnu.org> ---
Hi!

This ICE (or similar) is breaking the debian build on aarch64 (specifically for
the polymake package): https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=974058

I reduced to the following (invalid) testcase which hits the ICE on trunk
(reproduced on both x86 and aarch64):

constexpr int value = 1;
struct is_derived_from_instance_of;
template <bool, typename> struct enable_if;
template <bool _Cond, typename _Tp = void>
using enable_if_t = typename enable_if<_Cond, _Tp>::type;
template <typename> using is_generic_vector = is_derived_from_instance_of;
template <typename E> class matrix_methods {
  template <typename> using is_generic_matrix = is_derived_from_instance_of;
  template <typename, typename, typename, typename> struct block_matrix {
    template <typename Left, typename Right, typename Rowwise>
    block_matrix<Left, Right, Rowwise,
                 enable_if_t<value && is_generic_matrix<E>::value>>
        block_matrix<Left, Right, Rowwise,
                     enable_if_t<value && is_generic_vector<E>::value>>

This ICEs with:

$ aarch64-elf-gcc -c test.cc
test.cc:14:70: internal compiler error: canonical types differ for identical
types 'enable_if<(value && matrix_methods<E>::is_generic_matrix<E>::value),
void>' and 'enable_if<(value && is_generic_vector<E>::value), void>'
   14 |                      enable_if_t<value && is_generic_vector<E>::value>>
      |                                                                      ^~
0x98d86a comptypes(tree_node*, tree_node*, int)
        /home/alecop01/toolchain/src/gcc/gcc/cp/typeck.c:1538
0x98eb82 same_type_ignoring_top_level_qualifiers_p(tree_node*, tree_node*)
        /home/alecop01/toolchain/src/gcc/gcc/cp/typeck.c:1574
0x98cba4 structural_comptypes
        /home/alecop01/toolchain/src/gcc/gcc/cp/typeck.c:1423
0x98d6bd comptypes(tree_node*, tree_node*, int)
        /home/alecop01/toolchain/src/gcc/gcc/cp/typeck.c:1556
0x8b04bc template_args_equal(tree_node*, tree_node*, bool)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:9175
0x8afea7 comp_template_args(tree_node*, tree_node*, tree_node**, tree_node**,
bool)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:9222
0x8b0283 template_args_equal(tree_node*, tree_node*, bool)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:9146
0x8afea7 comp_template_args(tree_node*, tree_node*, tree_node**, tree_node**,
bool)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:9222
0x8bd1a3 spec_hasher::equal(spec_entry*, spec_entry*)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:1716
0x9263e3 hash_table<spec_hasher, false,
xcallocator>::find_with_hash(spec_entry* const&, unsigned int)
        /home/alecop01/toolchain/src/gcc/gcc/hash-table.h:923
0x8f32d8 lookup_template_class_1
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:9830
0x8f32d8 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        /home/alecop01/toolchain/src/gcc/gcc/cp/pt.c:10186
0x941d2f finish_template_type(tree_node*, tree_node*, int)
        /home/alecop01/toolchain/src/gcc/gcc/cp/semantics.c:3442
0x882bad cp_parser_template_id
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:16967
0x8830ea cp_parser_class_name
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:24190
0x886f96 cp_parser_qualifying_entity
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:6861
0x886f96 cp_parser_nested_name_specifier_opt
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:6543
0x887073 cp_parser_nested_name_specifier
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:6787
0x887127 cp_parser_ptr_operator
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:22243
0x87b800 cp_parser_declarator
        /home/alecop01/toolchain/src/gcc/gcc/cp/parser.c:21468
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.


I'm attempting to reduce a testcase which preserves the validity of the source
code, but this is proving to be much more expensive.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Alex Coplan <acoplan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0
   Last reconfirmed|2014-05-30 00:00:00         |2020-11-20
      Known to fail|                            |11.0

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #9 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This was fixed in r11-5942.  Alex, please try gcc with this revision.  If your
test still ICEs, please file a bug or reopen this one.  Thanks.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

--- Comment #10 from Alex Coplan <acoplan at gcc dot gnu.org> ---
Thanks. The testcase no longer ICEs on trunk.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---
                 CC|                            |nathan at gcc dot gnu.org

--- Comment #11 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
Sadly the 'fixing' commit was buggy, see 98372.

What;s happening here is that the two declarations are not known to be the same
until the second one is complete and matched with the first.  But they contain
an instantiation over decltype(earlier_arg), and the two different
'earlier_args' have different contexts (and so we think are different from the
POV of specializations), until we do the matching up and morph the second one
into the first.  After that the two parameter instances have the same context
and so we ICE.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.0                        |11.2

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 11.1 has been released, retargeting bugs to GCC 11.2.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[xry111 at mengyan1223 dot wang]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Xi Ruoyao <xry111 at mengyan1223 dot wang> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xry111 at mengyan1223 dot wang

--- Comment #13 from Xi Ruoyao <xry111 at mengyan1223 dot wang> ---
According to recent test results (for e.g.,
https://gcc.gnu.org/pipermail/gcc-testresults/2021-April/685744.html), it's no
longer ice-on-valid-code, but reject-valid-code now.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.2                        |---

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |12.0
                 CC|                            |jason at gcc dot gnu.org

--- Comment #14 from Jason Merrill <jason at gcc dot gnu.org> ---
This seems to be fixed on trunk.

[Bug c++/52830] ICE: "canonical types differ for identical types ..." when attempting SFINAE with member type

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52830

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0
         Resolution|---                         |FIXED
                 CC|                            |ppalka at gcc dot gnu.org
             Status|REOPENED                    |RESOLVED

--- Comment #15 from Patrick Palka <ppalka at gcc dot gnu.org> ---
(In reply to Jason Merrill from comment #14)
> This seems to be fixed on trunk.

Looks like ever since r12-3766, which also removed the dg-ice from
constexpr-52830.C, so I suppose we can close this PR then.