[Bug c++/116534] New: [14 regression] internal compiler error with comparison of pointers calculated with array offset

[Bug c++/116534] New: [14 regression] internal compiler error with comparison of pointers calculated with array offset

[john at drouhard dot dev]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116534

            Bug ID: 116534
           Summary: [14 regression] internal compiler error with
                    comparison of pointers calculated with array offset
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: john at drouhard dot dev
  Target Milestone: ---

The following produces an internal compiler when compiled with -Wall starting
with gcc 14:


$ cat test.cpp
template <class A>
class Test {
    void foo(unsigned x, unsigned y) {
        bool test = &a[x] == &b[y];
    }
    unsigned *a;
    unsigned *b;
};



$ g++ -Wall ./test.cpp
./test.cpp: In member function 'void Test<A>::foo(unsigned int, unsigned int)':
./test.cpp:4:34: internal compiler error: Segmentation fault
    4 |         bool test = &a[x] == &b[y];
      |                                  ^
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug c++/116534] [14 regression] internal compiler error with comparison of pointers calculated with array offset

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116534

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-08-29
           Keywords|                            |ice-on-valid-code
           Priority|P3                          |P2
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |14.3

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r14-4793:

commit dad311874ac3b3cf4eca1c04f67cae80c953f7b8
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Oct 20 10:45:00 2023 -0400

    c++: remove NON_DEPENDENT_EXPR, part 1

[Bug c++/116534] [14/15 regression] internal compiler error with comparison of pointers calculated with array offset

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116534

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
            Summary|[14 regression] internal    |[14/15 regression] internal
                   |compiler error with         |compiler error with
                   |comparison of pointers      |comparison of pointers
                   |calculated with array       |calculated with array
                   |offset                      |offset
             Status|NEW                         |ASSIGNED

[Bug c++/116534] [14/15 regression] internal compiler error with comparison of pointers calculated with array offset

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116534

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:7ca486889b1b1c7e7bcbbca3b6caa103294ec07d

commit r15-3673-g7ca486889b1b1c7e7bcbbca3b6caa103294ec07d
Author: Marek Polacek <polacek@redhat.com>
Date:   Thu Aug 29 10:40:50 2024 -0400

    c++: ICE with -Wtautological-compare in template [PR116534]

    Pre r14-4793, we'd call warn_tautological_cmp -> operand_equal_p
    with operands wrapped in NON_DEPENDENT_EXPR, which works, since
    o_e_p bails for codes it doesn't know.  But now we pass operands
    not encapsulated in NON_DEPENDENT_EXPR, and crash, because the
    template tree for &a[x] has null DECL_FIELD_OFFSET.

    This patch extends r12-7797 to cover the case when DECL_FIELD_OFFSET
    is null.

            PR c++/116534

    gcc/ChangeLog:

            * fold-const.cc (operand_compare::operand_equal_p): If either
            field's DECL_FIELD_OFFSET is null, compare the fields with ==.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wtautological-compare4.C: New test.

    Reviewed-by: Jason Merrill <jason@redhat.com>

[Bug c++/116534] [14 regression] internal compiler error with comparison of pointers calculated with array offset

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116534

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[14/15 regression] internal |[14 regression] internal
                   |compiler error with         |compiler error with
                   |comparison of pointers      |comparison of pointers
                   |calculated with array       |calculated with array
                   |offset                      |offset

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed on trunk so far.