[Bug c++/114997] New: ICE with -std=c++20: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[Bug c++/114997] New: ICE with -std=c++20: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[clopez at igalia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

            Bug ID: 114997
           Summary: ICE with -std=c++20: unexpected expression
                    ‘static_cast<UnsignedType>('\"')’ of kind
                    static_cast_expr
           Product: gcc
           Version: 12.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: clopez at igalia dot com
  Target Milestone: ---

Created attachment 58137
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58137&action=edit
preprocessed file from JSONObject.cpp to reproduce the problem

On the WebKit project recently this commit landed:
https://github.com/WebKit/WebKit/commit/4855c7a1dc4214523c0b3d0c430215456ed7a0a9

It caused GCC-12 to fail with an ICE.

./Source/JavaScriptCore/runtime/JSONObject.cpp: In lambda function:
./Source/JavaScriptCore/runtime/JSONObject.cpp:1124:89: internal compiler
error: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind
static_cast_expr
 1124 |                 constexpr auto quoteMask =
WTF::splatBulk(static_cast<UnsignedType>('"'));
      |                                                                        
                ^
0x7ffb005ff1c9 __libc_start_call_main
        ../sysdeps/nptl/libc_start_call_main.h:58
0x7ffb005ff284 __libc_start_main_impl
        ../csu/libc-start.c:360
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.

I checked that it fails with the last released version of GCC 12 (12.3.0) both
from Yocto
when cross-building for ARM64 as well as the GCC 12.3.0 shipped in
Debian/testing.

On Debian I tested with gcc-13 and with it builds fine.

I'm attaching the .ii file to reproduce the problem (compressed with xz as it
is quite big)

To reproduce it, download the .ii file and simple execute this command:


  g++-12 -O3 --std=c++20 -c JSONObject.ii


Not sure if useful information, but the original compiler command had the
following switches enabled

g++-12 -DBUILDING_JavaScriptCore -DBUILDING_WEBKIT=1 -DBUILDING_WITH_CMAKE=1
-DBUILDING_WPE__=1 -DBWRAP_EXECUTABLE=\"/usr/bin/bwrap\"
-DDBUS_PROXY_EXECUTABLE=\"/usr/bin/xdg-dbus-proxy\" -DGETTEXT_PACKAGE=\"WPE\"
-DHAVE_CONFIG_H=1 -DJSC_GLIB_API_ENABLED -DPAS_BMALLOC=1
-DPKGLIBDIR=\"/usr/local/lib/wpe-webkit-2.0\" -DSTATICALLY_LINKED_WITH_WTF
-DSTATICALLY_LINKED_WITH_bmalloc
[...-I/long/list/of/includes/excluded/for/clarity...]
-fdiagnostics-color=always -Wextra -Wall  -fmax-errors=20 -Wno-odr
-Wno-stringop-overread -Wno-stringop-overflow -Wno-nonnull -Wno-array-bounds
-Wno-expansion-to-defined -Wno-noexcept-type -Wno-psabi
-Wno-misleading-indentation -Wno-maybe-uninitialized -Wundef -Wpointer-arith
-Wmissing-format-attribute -Wformat-security -Wcast-align
-Wno-tautological-compare -fno-strict-aliasing -fno-exceptions -fno-rtti
-ffunction-sections -fdata-sections -O3 -DNDEBUG -fPIC -fvisibility=hidden
-fvisibility-inlines-hidden -ffp-contract=off -std=c++20 -c
Source/JavaScriptCore/runtime/JSONObject.cpp

[Bug c++/114997] ICE with -std=c++20: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[clopez at igalia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

--- Comment #1 from Carlos Alberto Lopez Perez <clopez at igalia dot com> ---
The original cpp file that causes the issue can be found here:
https://raw.githubusercontent.com/WebKit/WebKit/4855c7a1dc4214523c0b3d0c430215456ed7a0a9/Source/JavaScriptCore/runtime/JSONObject.cpp

just for reference, the md5hash of the file is

$ md5sum Source/JavaScriptCore/runtime/JSONObject.cpp
a4799453f1b2b3c0e2bec60a095c962d  Source/JavaScriptCore/runtime/JSONObject.cpp

[Bug c++/114997] ICE with -std=c++20: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[clopez at igalia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

--- Comment #2 from Carlos Alberto Lopez Perez <clopez at igalia dot com> ---
On WebKit we finally work-arounded the problem by replacing `constexpr` with
`const` at commit
https://github.com/WebKit/WebKit/commit/1ee00a2309c03ed119e8591022ba14f936440d71

[Bug c++/114997] ICE with -std=c++20: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced testcase:
```
typedef int vv __attribute__((__vector_size__(sizeof(int))));
constexpr vv ff(int code) { return vv{code}; }
template <typename _Tp> struct h {
    typedef _Tp type;
};
template <class T> void f() {
    using ut = h<unsigned char>::type;
    constexpr auto c = ff(static_cast<ut>('\\'));
}
```

[Bug c++/114997] ICE: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
My reduced testcase has failed since 4.8.0 and started to pass in GCC 13.1.0.
I wonder what fixed it (I suspect r13-3438  and if so I doubt that can be
backported).

Note the issue is with constexpr and vector initializers (which is why I
suspect r13-3438  was the fix).

[Bug c++/114997] [11/12 Only] ICE: unexpected expression ‘static_cast<UnsignedType>('\"')’ of kind static_cast_expr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114997

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.5
            Summary|ICE: unexpected expression  |[11/12 Only] ICE:
                   |‘static_cast<UnsignedType>( |unexpected expression
                   |'\"')’ of kind              |‘static_cast<UnsignedType>(
                   |static_cast_expr            |'\"')’ of kind
                   |                            |static_cast_expr