https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85951
Bug ID: 85951
Summary: make_signed and make_unsigned are incorrect for
wchar_t, char16_t, and char32_t
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: kretz at kde dot org
Target Milestone: ---
make_(un)signed_t of char16_t, char32_t, or wchar_t should never be
char16_t/char32_t/wchar_t, just like it is the case for make_signed_t<char>
(which is signed char).
According to http://eel.is/c++draft/basic.fundamental#2 and #3 char16_t,
char32_t, and wchar32_t are neither _signed integer types_ nor _unsigned
integer types_. Therefore, the third outcome in
http://eel.is/c++draft/meta.trans.sign applies: "type names the (un)signed
integer type with smallest rank for which sizeof(T) == sizeof(type), with the
same cv-qualifiers as T".
cf. https://godbolt.org/g/aG4CnD
