[Bug c++/89814] New: [9 Regression] ICE (segfault) with -Wduplicated-cond

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89814

            Bug ID: 89814
           Summary: [9 Regression] ICE (segfault) with -Wduplicated-cond
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Keywords: diagnostic, ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
  Target Milestone: ---

GCC 9.0.1 20190325/x86_64-pc-linux-gnu
now segfaults with "g++ -Wduplicated-cond" - it worked about a week ago.


The real-world fail is in:

gcc-trunk/include/c++/9.0.1/bits/stl_iterator_base_funcs.h: In function
‘constexpr void std::__advance(_RandomAccessIterator&, _Distance,
std::random_access_iterator_tag)’:
gcc-trunk/include/c++/9.0.1/bits/stl_iterator_base_funcs.h:182:54: internal
compiler error: Segmentation fault


Backtrace of the fail below:

0xfadc8f crash_signal
        ../../gcc/toplev.c:326
0xcabedc operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/fold-const.c:2977
0xcac09a operand_equal_p(tree_node const*, tree_node const*, unsigned int)
        ../../gcc/fold-const.c:2950
0xb1d951 warn_duplicated_cond_add_or_warn(unsigned int, tree_node*,
vec<tree_node*, va_heap, vl_ptr>**)
        ../../gcc/c-family/c-warn.c:2318
0x9d4b05 cp_parser_selection_statement
        ../../gcc/cp/parser.c:11809


//----------------------
struct forward_iterator_tag { };
struct random_access_iterator_tag { };

template < typename _RandomAccessIterator,
           typename _Distance >
inline constexpr void
__advance (_RandomAccessIterator & __i, _Distance __n,
           random_access_iterator_tag)
{
  if (__builtin_constant_p (__n) && __n == 1)
    ++__i;
  else if (__builtin_constant_p (__n) && __n == -1)
    --__i;
  else
    __i += __n;
}