[Bug c++/95705] New: Internal compiler error generated when using int cast as array index

[staffordstyle at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95705

            Bug ID: 95705
           Summary: Internal compiler error generated when using int cast
                    as array index
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: staffordstyle at gmail dot com
  Target Milestone: ---

main.ii
===================================
# 1 "main.cpp"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 1 "<command-line>" 2
# 1 "main.cpp"
struct IntLike
{
  operator int() const
  {
    return 0;
  }
};

template<typename T>
void useAsArrayIndex( const IntLike a )
{
  float myArray[1];
  myArray[ a ];
}

int main()
{
}


Compile command:
===================================
g++ -save-temps main.cpp
main.cpp: In function ‘void useAsArrayIndex(IntLike)’:
main.cpp:13:14: internal compiler error: unexpected expression ‘(int)a’ of kind
implicit_conv_expr
   13 |   myArray[ a ];
      |              ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.


Compiler version:
===================================
g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/home/me/toolchain/install/libexec/gcc/x86_64-pc-linux-gnu/10.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/me/toolchain/source/gcc/./configure
--prefix=/home/me/toolchain/install --disable-multilib --disable-bootstrap
--enable-shared --enable-languages=c,c++,fortran
--with-mpc=/home/me/toolchain/install --with-mpfr=/home/me/toolchain/install
--with-gmp=/home/me/toolchain/install --with-isl=/home/me/toolchain/install
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.1.0 (GCC)



I also tested on godbolt with these versions of GCC:
9.3 no error
10.1 same error as above
11 same error as above

Also, thank you for GCC.