https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89728
Bug ID: 89728
Summary: ctype is underconstrained
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: antoshkka at gmail dot com
Target Milestone: ---
Because of that overloads from [locale.convenience] compile well with creepy
charT template arguments like std::string:
std::tolower(std::string{}, std::locale::classic());
That leads to runtime exceptions (bad cast to ctype<basic_string<char>>)
instead of a compile time.
Some other standard library implementations are more restrictive and do not
allow such weird template parameters for ctype:
error: implicit instantiation of undefined template
'std::__1::ctype<std::__1::basic_string<char> >'
