[Bug libstdc++/82685] New: basic_string_view<char> operator""sv(const char*, size_t) should be noexcept

["pavel.kryukov at phystech dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82685

            Bug ID: 82685
           Summary: basic_string_view<char> operator""sv(const char*,
                    size_t) should be noexcept
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pavel.kryukov at phystech dot edu
  Target Milestone: ---

`string_view` literal operators should have 'noexcept' specifier according to
the C++17 standard:
https://github.com/cplusplus/draft/blob/4ba4e9c2c04b7680ac2a56b65c241ec10c427c3f/source/strings.tex#L4611

Currently GCC implements the literal operators via
`basic_string_view<_charT>(const _charT*, size_t)` ctor which may throw an
exception according to the same standard.
https://github.com/gcc-mirror/gcc/blob/0f6374027d3cd77f80f353eb1c2c61c5ad2b6dfd/libstdc%2B%2B-v3/include/std/string_view#L638