[Bug c++/107755] New: ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[Bug c++/107755] New: ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[pokechu022+gccbugzilla at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

            Bug ID: 107755
           Summary: ICE: in fold_convert_loc, at fold-const.c:2435, with
                    -Wlogical-op, implicit user-defined conversion
                    operator, template function, logical operator, and
                    conditional operator
           Product: gcc
           Version: 10.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pokechu022+gccbugzilla at gmail dot com
  Target Milestone: ---

Created attachment 53928
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53928&action=edit
failing code using (!false && (false ? a : b))

A combination of -Wlogical-op, a template function, an implicit user-defined
conversion operator, a logical AND or OR operator, and a ternary conditional
operator results in an ICE.

```
$ gcc-10 -Wlogical-op -save-temps test.cpp
test.cpp: In function ‘bool Bar()’:
test.cpp:12:35: internal compiler error: in fold_convert_loc, at
fold-const.c:2435
   12 |   return (!false && (false ? a : b));
      |                                   ^
0x7f08a2bf4082 __libc_start_main
        ../csu/libc-start.c:308
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-10/README.Bugs> for instructions.
$ gcc-10 -v
Using built-in specs.
COLLECT_GCC=gcc-10
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
10.3.0-1ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-10
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-10-S4I5Pr/gcc-10-10.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-S4I5Pr/gcc-10-10.3.0/debian/tmp-gcn/usr,hsa
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.3.0 (Ubuntu 10.3.0-1ubuntu1~20.04)
```

I tested at https://godbolt.org/z/574Wq1Ws5 and found that this issue was not
present in 4.7.4 and is present in 4.8.1, 12.2, and trunk. Here's the output on
trunk from compiler explorer, for convenience:

```
Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/gcc-snapshot/bin/g++
Target: x86_64-linux-gnu
Configured with: ../gcc-trunk-20221118/configure
--prefix=/opt/compiler-explorer/gcc-build/staging --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu
--enable-languages=c,c++,fortran,ada,objc,obj-c++,d --enable-ld=yes
--enable-gold=yes --enable-libstdcxx-debug --enable-libstdcxx-time=yes
--enable-linker-build-id --enable-lto --enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build-gcc-7b3b2f50953c5143d4b14b59d322d8a793f411dd-binutils-2.38
--enable-libstdcxx-backtrace=yes
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 13.0.0 20221117 (experimental)
(Compiler-Explorer-Build-gcc-7b3b2f50953c5143d4b14b59d322d8a793f411dd-binutils-2.38) 
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' '/app/output.s'
'-masm=intel' '-S' '-Wlogical-op' '-v' '-shared-libgcc' '-mtune=generic'
'-march=x86-64' '-dumpdir' '/app/'

/opt/compiler-explorer/gcc-trunk-20221118/bin/../libexec/gcc/x86_64-linux-gnu/13.0.0/cc1plus
-quiet -v -imultiarch x86_64-linux-gnu -iprefix
/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/
-D_GNU_SOURCE <source> -quiet -dumpdir /app/ -dumpbase output.cpp -dumpbase-ext
.cpp -masm=intel -mtune=generic -march=x86-64 -g -Wlogical-op -version
-fdiagnostics-color=always -o /app/output.s
GNU C++17
(Compiler-Explorer-Build-gcc-7b3b2f50953c5143d4b14b59d322d8a793f411dd-binutils-2.38)
version 13.0.0 20221117 (experimental) (x86_64-linux-gnu)
        compiled by GNU C version 9.4.0, GMP version 6.2.1, MPFR version 4.1.0,
MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/backward"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/include-fixed/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/include-fixed"
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/x86_64-linux-gnu

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/backward

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/include

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/include-fixed/x86_64-linux-gnu

/opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/x86_64-linux-gnu/13.0.0/include-fixed
 /usr/local/include
 /opt/compiler-explorer/gcc-trunk-20221118/bin/../lib/gcc/../../include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C++17
(Compiler-Explorer-Build-gcc-7b3b2f50953c5143d4b14b59d322d8a793f411dd-binutils-2.38)
version 13.0.0 20221117 (experimental) (x86_64-linux-gnu)
        compiled by GNU C version 9.4.0, GMP version 6.2.1, MPFR version 4.1.0,
MPC version 1.2.1, isl version isl-0.24-GMP

GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: d17bd4a13b030ab0955e667094fe2b0e
<source>: In function 'bool Bar()':
<source>:12:35: internal compiler error: in fold_convert_loc, at
fold-const.cc:2495
   12 |   return (!false && (false ? a : b));
      |                                   ^
0x23ac0ce internal_error(char const*, ...)
        ???:0
0xaaf7fc fancy_abort(char const*, int, char const*)
        ???:0
0xfb89a1 fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0xfc093d fold_build2_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ???:0
0xfcc891 build_range_check(unsigned int, tree_node*, tree_node*, int,
tree_node*, tree_node*)
        ???:0
0xfcc857 build_range_check(unsigned int, tree_node*, tree_node*, int,
tree_node*, tree_node*)
        ???:0
0xdfe839 warn_logical_operator(unsigned int, tree_code, tree_node*, tree_code,
tree_node*, tree_code, tree_node*)
        ???:0
0xae1b92 build_new_op(op_location_t const&, tree_code, int, tree_node*,
tree_node*, tree_node*, tree_node*, tree_node**, int)
        ???:0
0xd42852 build_x_binary_op(op_location_t const&, tree_code, tree_node*,
tree_code, tree_node*, tree_code, tree_node*, tree_node**, int)
        ???:0
0xc8e277 c_parse_file()
        ???:0
0xdd7a09 c_common_parse_file()
        ???:0
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.
Compiler returned: 1
```

A few variants that also trigger the same ICE. The first operand to the ternary
operator can be anything (false, true, a bool parameter, etc.). The logical
operator can be either || or &&, and the ternary operator can be on either side
of it. The other operand of the logical operator can be a bool parameter or
!false or !true (but using false or true without a NOT avoids the ICE, probably
due to a separate optimisation). The function containing the ternary operator
must be a template, even if the template parameters are not used.

The second and third operands to the ternary operator must be of different
types and must use an implicit user-defined conversion operator. In my example,
I compared a bool to a type implicitly convertible to bool, but this also
happens with int + implicit conversion to bool, int + implicit conversion to
int, two distinct types implicitly convertible to bool, two types implicitly
convertible to int, etc. It does not happen if the same type (including
template parameters) is used for both operands, nor if no user-defined
conversion operator is involved (e.g. int + bool).

This issue was originally found at
https://github.com/dolphin-emu/dolphin/pull/11289.

[Bug c++/107755] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[pokechu022+gccbugzilla at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

Pokechu22 <pokechu022+gccbugzilla at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |10.3.0, 12.2.0, 4.8.1,
                   |                            |9.4.0
      Known to work|                            |4.7.4

--- Comment #1 from Pokechu22 <pokechu022+gccbugzilla at gmail dot com> ---
Here are a few cases that would be useful to include in a test:

```
return (!false && (false ? a : b));
return (!true && (false ? a : b));
return (!false || (false ? a : b));
return (!true || (false ? a : b));
return (x && (y ? a : b));
return (x || (y ? a : b));
```

As an aside, `(false | (false ? a : b))` (where a is bool and b is Foo) used to
cause an ICE (confirmed in 4.7.4, 4.8.1, and 5.5). This was fixed in or before
6.1. I can't find a bug report corresponding to that issue either, but it
probably should be verified that that doesn't regress either.

[Bug c++/107755] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-11-21
                 CC|                            |marxin at gcc dot gnu.org

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed.

[Bug c++/107755] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

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

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

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Must have started with r187194.

[Bug c++/107755] [10/11/12/13 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.5
           Priority|P3                          |P2
           Keywords|                            |ice-on-valid-code
            Summary|ICE: in fold_convert_loc,   |[10/11/12/13 Regression]
                   |at fold-const.c:2435, with  |ICE: in fold_convert_loc,
                   |-Wlogical-op, implicit      |at fold-const.c:2435, with
                   |user-defined conversion     |-Wlogical-op, implicit
                   |operator, template          |user-defined conversion
                   |function, logical operator, |operator, template
                   |and conditional operator    |function, logical operator,
                   |                            |and conditional operator

[Bug c++/107755] [10/11/12/13 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
One possible fix would be not to emit these warnings while
processing_template_decl, the warning goes too deep into the expressions and
even when the operands are neither type nor value dependent, if
processing_template_decl they are far from what the middle-end code can grok.
I wonder where IMPLICIT_CONV_EXPR gets lost, so the COND_EXPR with
boolean_type_node type has RECORD_TYPE operand.

[Bug c++/107755] [10/11/12/13 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

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

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think so too.

[Bug c++/107755] [10/11/12/13 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

--- Comment #6 from CVS 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:5ce8961b46f050a96e8c542b34b1cf024ba95f1b

commit r13-5627-g5ce8961b46f050a96e8c542b34b1cf024ba95f1b
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Jan 31 14:36:30 2023 -0500

    c++: ICE with -Wlogical-op [PR107755]

    Here we crash in the middle end because warn_logical_operator calls
    build_range_check which calls various fold_* functions and those
    don't work too well when we're still processing template trees.  For
    instance here we crash because we're converting a RECORD_TYPE to bool.
    At this point VIEW_CONVERT_EXPR<struct Foo>(b) hasn't yet been converted
    to Foo::operator bool (&b).

    I was excited to fix this with instantiation_dependent_expression_p
    which can now be called from c-family/ as well, but the problem isn't
    that the expression is dependent.  So, p_t_d it is.

            PR c++/107755

    gcc/cp/ChangeLog:

            * call.cc (build_new_op): Don't call warn_logical_operator when
            processing a template.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wlogical-op-4.C: New test.

[Bug c++/107755] [10/11/12/13 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Marek Polacek
<mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:fb2d50f72caf3b84b315bc760368670680999749

commit r12-9095-gfb2d50f72caf3b84b315bc760368670680999749
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Jan 31 14:36:30 2023 -0500

    c++: ICE with -Wlogical-op [PR107755]

    Here we crash in the middle end because warn_logical_operator calls
    build_range_check which calls various fold_* functions and those
    don't work too well when we're still processing template trees.  For
    instance here we crash because we're converting a RECORD_TYPE to bool.
    At this point VIEW_CONVERT_EXPR<struct Foo>(b) hasn't yet been converted
    to Foo::operator bool (&b).

    I was excited to fix this with instantiation_dependent_expression_p
    which can now be called from c-family/ as well, but the problem isn't
    that the expression is dependent.  So, p_t_d it is.

            PR c++/107755

    gcc/cp/ChangeLog:

            * call.cc (build_new_op): Don't call warn_logical_operator when
            processing a template.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wlogical-op-4.C: New test.

    (cherry picked from commit 5ce8961b46f050a96e8c542b34b1cf024ba95f1b)

[Bug c++/107755] [10/11 Regression] ICE: in fold_convert_loc, at fold-const.c:2435, with -Wlogical-op, implicit user-defined conversion operator, template function, logical operator, and conditional operator

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107755

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
            Summary|[10/11/12/13 Regression]    |[10/11 Regression] ICE: in
                   |ICE: in fold_convert_loc,   |fold_convert_loc, at
                   |at fold-const.c:2435, with  |fold-const.c:2435, with
                   |-Wlogical-op, implicit      |-Wlogical-op, implicit
                   |user-defined conversion     |user-defined conversion
                   |operator, template          |operator, template
                   |function, logical operator, |function, logical operator,
                   |and conditional operator    |and conditional operator
         Resolution|---                         |FIXED

--- Comment #8 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.