[Bug c++/113031] New: [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[Bug c++/113031] New: [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

            Bug ID: 113031
           Summary: [14 Regression] ICE in cxx_fold_indirect_ref_1
                    starting with r14-6508
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
                CC: nathanieloshead at gmail dot com
  Target Milestone: ---

I'm seeing new ICEs in the libstdc++ testsuite with the following non-default
settings:

> 
> GLIBCXX_TESTSUITE_STDS=20 make check RUNTESTFLAGS="--target_board=unix/-D_GLIBCXX_USE_CXX11_ABI=0"
> 


/home/jwakely/src/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/include/variant:1626:17:
internal compiler error: Segmentation fault
0x11373c4 crash_signal
       ../../gcc/toplev.cc:316
0x496192 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5712
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
0x496487 cxx_fold_indirect_ref_1
       ../../gcc/cp/constexpr.cc:5743
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Created attachment 56884
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56884&action=edit
Gzipped preprocessed source

Compile the attached .ii with '-std=gnu++20 -O' (or any non-zero optimization
level) to reproduce the ICE.

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
   Target Milestone|---                         |14.0

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[nathanieloshead at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

--- Comment #2 from Nathaniel Shead <nathanieloshead at gmail dot com> ---
Reduced to:


template <typename> class variant;

template <typename _Types, typename _Tp>
auto __variant_cast(_Tp __rhs) { return static_cast<variant<_Types>&&>(__rhs);
}

template <typename _Types>
struct _Move_assign_base : _Types {
  void operator=(_Move_assign_base __rhs) { __variant_cast<_Types>(__rhs); }
};

template <typename _Types>
struct variant : _Move_assign_base<_Types> {
  void emplace() {
    variant __tmp;
    *this = __tmp;
  }
};

struct _Undefined_class {
  struct _Nocopy_types {
    void (_Undefined_class::*_M_member_pointer)();
  };
  struct function : _Nocopy_types {
    struct optional {
      void test03() {
        variant<function> v;
        v.emplace();
      }
    };
  };
};


The following patch seems to fix the immediate problem (but not yet fully
regtested):

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index e1b2d27fc36..051f73fb73f 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -5709,7 +5709,8 @@ cxx_fold_indirect_ref_1 (const constexpr_ctx *ctx,
location_t loc, tree type,
          }

       /* Handle conversion to "as base" type.  */
-      if (CLASSTYPE_AS_BASE (optype) == type)
+      if (CLASS_TYPE_P (optype)
+         && CLASSTYPE_AS_BASE (optype) == type)
        return op;

       /* Handle conversion to an empty base class, which is represented with a

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-12-15
     Ever confirmed|0                           |1

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
That was quick, thanks!

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathaniel Shead <nshead@gcc.gnu.org>:

https://gcc.gnu.org/g:39f9c426f58448d6df340cdccd84e05721a20921

commit r14-6619-g39f9c426f58448d6df340cdccd84e05721a20921
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Sat Dec 16 10:59:03 2023 +1100

    c++: Fix unchecked use of CLASSTYPE_AS_BASE [PR113031]

    My previous commit (naively) assumed that a TREE_CODE of RECORD_TYPE or
    UNION_TYPE was sufficient for optype to be considered a "class type".
    However, this does not account for e.g. template type parameters of
    record or union type. This patch corrects to check for CLASS_TYPE_P
    before checking for as-base conversion.

            PR c++/113031

    gcc/cp/ChangeLog:

            * constexpr.cc (cxx_fold_indirect_ref_1): Check for CLASS_TYPE
            before using CLASSTYPE_AS_BASE.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/pr113031.C: New test.

    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

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

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

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So fixed?

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[nathanieloshead at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

--- Comment #6 from Nathaniel Shead <nathanieloshead at gmail dot com> ---
Yes, fixed as far as I'm aware.

[Bug c++/113031] [14 Regression] ICE in cxx_fold_indirect_ref_1 starting with r14-6508

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113031

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

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

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
.