[Bug c++/107335] New: call to throw_bad_cast even with -fno-exceptions

[Bug c++/107335] New: call to throw_bad_cast even with -fno-exceptions

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

            Bug ID: 107335
           Summary: call to throw_bad_cast even with -fno-exceptions
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hiraditya at msn dot com
  Target Milestone: ---

Testcase:
#include<iostream>

void foo() {
    std::cout << std::endl;
}

$ g++ -std=c++17 -O3 -fno-exceptions

```asm
foo():
        mov     rax, QWORD PTR std::cout[rip]
        push    rbx
        mov     rax, QWORD PTR [rax-24]
        mov     rbx, QWORD PTR std::cout[rax+240]
        test    rbx, rbx
        je      .L10
        cmp     BYTE PTR [rbx+56], 0
        je      .L5
        movsx   esi, BYTE PTR [rbx+67]
.L6:
        mov     edi, OFFSET FLAT:std::cout
        call    std::basic_ostream<char, std::char_traits<char> >::put(char)
        pop     rbx
        mov     rdi, rax
        jmp     std::basic_ostream<char, std::char_traits<char> >::flush()
.L5:
        mov     rdi, rbx
        call    std::ctype<char>::_M_widen_init() const
        mov     rax, QWORD PTR [rbx]
        mov     esi, 10
        mov     rax, QWORD PTR [rax+48]
        cmp     rax, OFFSET FLAT:_ZNKSt5ctypeIcE8do_widenEc
        je      .L6
        mov     rdi, rbx
        call    rax
        movsx   esi, al
        jmp     .L6
.L10: 
        call    std::__throw_bad_cast() <----------- call to __throw_bad_cast
_GLOBAL__sub_I_foo():
        sub     rsp, 8
        mov     edi, OFFSET FLAT:_ZStL8__ioinit
        call    std::ios_base::Init::Init() [complete object constructor]
        mov     edx, OFFSET FLAT:__dso_handle
        mov     esi, OFFSET FLAT:_ZStL8__ioinit
        mov     edi, OFFSET FLAT:_ZNSt8ios_base4InitD1Ev
        add     rsp, 8
        jmp     __cxa_atexit
```

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-10-20
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
 
[/opt/compiler-explorer/gcc-trunk-20221020/include/c++/13.0.0/bits/basic_ios.h:50:18]
std::__throw_bad_cast ();

Inside include/bits/basic_ios.h :

  template<typename _Facet>
    inline const _Facet&
    __check_facet(const _Facet* __f)
    {
      if (!__f)
        __throw_bad_cast();
      return *__f;
    }

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
But that's not a throw, it's a function call. If the definition of that
function is compiled without exceptions then it will abort instead of throw.

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
So what exactly is the bug? You want the abort to happen right there? There are
dozens of place we call functions like that instead of throwing.

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

--- Comment #4 from AK <hiraditya at msn dot com> ---
I wasn't sure if this is expected. Thanks for clarifying.

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

--- Comment #5 from AK <hiraditya at msn dot com> ---
Is this the definition of throw_bad_cast?

https://github.com/gcc-mirror/gcc/blob/16e2427f50c208dfe07d07f18009969502c25dc8/gcc/cp/rtti.c#L221

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to AK from comment #5)
> Is this the definition of throw_bad_cast?
> 
> https://github.com/gcc-mirror/gcc/blob/
> 16e2427f50c208dfe07d07f18009969502c25dc8/gcc/cp/rtti.c#L221

No.
The definition is in libstdc++v3/src/c++11/functexcept.cc .

[Bug libstdc++/107335] call to throw_bad_cast even with -fno-exceptions

[hiraditya at msn dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107335

AK <hiraditya at msn dot com> changed:

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

--- Comment #7 from AK <hiraditya at msn dot com> ---
not a bug