This implements P2362, which has not yet been approved by the
C++ committee, but because wide-multi character literals are
implementation defined, clang might not have to wait for WG21.
This change is also being applied in C mode as the behavior is
implementation-defined in C as well and there's no benefit to
having different rules between the languages.
The other part of P2362, making non-representable character
literals ill-formed, is already implemented by clang
Move the logic for determining the `wchar_t` type information into the
driver. Rather than passing the single bit of information of
`-fshort-wchar` indicate to the frontend the desired type of `wchar_t`
through a new `-cc1` option of `-fwchar-type` and indicate the
signedness through `-f{,no-}signed-wchar`. This replicates the current
logic which was spread throughout Basic into the
`RenderCharacterOptions`.
Most of the changes to the tests are to ensure that the frontend uses
the correct type. Add a new test set under `test/Driver/wchar_t.c` to
ensure that we calculate the proper types for the various cases.
llvm-svn: 315126
Corentin Jabot