[Bug c++/95508] New: [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[Bug c++/95508] New: [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

            Bug ID: 95508
           Summary: [10/11 Regression] ICE on unexpected expression
                    implicit_conv_expr since r10-7096
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

Since r10-7096-gd417b4f5414d9076300ab41974a14424f722688c the following testcase
ICEs:
template <typename>
struct A;
template <typename>
struct B {
  operator int () { return 0; }
};
template <>
struct A<unsigned> : B<int> {};
struct D {
  template <typename>
  int foo () { return e[f]; }
  int e[6];
  A<unsigned> f;
};
rh1837006.C: In member function ‘int D::foo()’:
rh1837006.C:11:26: internal compiler error: unexpected expression
‘(int)((D*)this)->D::f’ of kind implicit_conv_expr
   11 |   int foo () { return e[f]; }
      |                          ^
0xaf874b cxx_eval_constant_expression
        ../../gcc/cp/constexpr.c:6541
0xaf8cef cxx_eval_outermost_constant_expr
        ../../gcc/cp/constexpr.c:6746
0xafd0db maybe_constant_value(tree_node*, tree_node*, bool)
        ../../gcc/cp/constexpr.c:7019
0xcc3e00 cp_build_array_ref(unsigned int, tree_node*, tree_node*, int)
        ../../gcc/cp/typeck.c:3568
...

[Bug c++/95508] [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
                 CC|                            |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |10.2
           Priority|P3                          |P2
   Last reconfirmed|                            |2020-06-03
             Status|UNCONFIRMED                 |NEW

[Bug c++/95508] [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

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

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

[Bug c++/95508] [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |staffordstyle at gmail dot com

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
*** Bug 95705 has been marked as a duplicate of this bug. ***

[Bug c++/95508] [10/11 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

--- Comment #2 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:ae2ebf011fec926e003645c33c07a03619ea216a

commit r11-1449-gae2ebf011fec926e003645c33c07a03619ea216a
Author: Marek Polacek <polacek@redhat.com>
Date:   Wed Jun 17 09:19:02 2020 -0400

    c++: ICE with IMPLICIT_CONV_EXPR in array subscript [PR95508]

    Since r10-7096 convert_like, when called in a template, creates an
    IMPLICIT_CONV_EXPR when we're converting to/from array type.

    In this test, we have e[f], and we're converting f (of type class A) to
    int, so convert_like in build_new_op_1 created the IMPLICIT_CONV_EXPR
    that got into cp_build_array_ref which calls maybe_constant_value.  My
    patch above failed to adjust this spot to call fold_non_dependent_expr
    instead, which can handle codes like I_C_E in a template.  Fixed by
    using a new function maybe_fold_non_dependent_expr, which, if the expr
    can't be evaluated to a constant, returns the original expression.

    gcc/cp/ChangeLog:

            PR c++/95508
            * constexpr.c (maybe_fold_non_dependent_expr): New.
            * cp-tree.h (maybe_fold_non_dependent_expr): Declare.
            * typeck.c (cp_build_array_ref): Call maybe_fold_non_dependent_expr
            instead of maybe_constant_value.

    gcc/testsuite/ChangeLog:

            PR c++/95508
            * g++.dg/template/conv16.C: New test.

[Bug c++/95508] [10 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[10/11 Regression] ICE on   |[10 Regression] ICE on
                   |unexpected expression       |unexpected expression
                   |implicit_conv_expr since    |implicit_conv_expr since
                   |r10-7096                    |r10-7096

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed on trunk, testing 10 now.

[Bug c++/95508] [10 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Marek Polacek
<mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:1bab254fd30c2b94a675b9057349fc80946375b1

commit r10-8315-g1bab254fd30c2b94a675b9057349fc80946375b1
Author: Marek Polacek <polacek@redhat.com>
Date:   Wed Jun 17 14:38:05 2020 -0400

    c++: ICE with IMPLICIT_CONV_EXPR in array subscript [PR95508]

    Since r10-7096 convert_like, when called in a template, creates an
    IMPLICIT_CONV_EXPR when we're converting to/from array type.

    In this test, we have e[f], and we're converting f (of type class A) to
    int, so convert_like in build_new_op_1 created the IMPLICIT_CONV_EXPR
    that got into cp_build_array_ref which calls maybe_constant_value.  My
    patch above failed to adjust this spot to call fold_non_dependent_expr
    instead, which can handle codes like I_C_E in a template.  Fixed by
    using a new function maybe_fold_non_dependent_expr, which, if the expr
    can't be evaluated to a constant, returns the original expression.

    gcc/cp/ChangeLog:

            PR c++/95508
            * constexpr.c (maybe_fold_non_dependent_expr): New.
            * cp-tree.h (maybe_fold_non_dependent_expr): Declare.
            * typeck.c (cp_build_array_ref): Call maybe_fold_non_dependent_expr
            instead of maybe_constant_value.

    gcc/testsuite/ChangeLog:

            PR c++/95508
            * g++.dg/template/conv16.C: New test.

[Bug c++/95508] [10 Regression] ICE on unexpected expression implicit_conv_expr since r10-7096

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95508

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

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

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.