This is a missing piece for C99 conformance.
This patch handles UCNs by adding a '\\' case to LexTokenInternal and
LexIdentifier -- if we see a backslash, we tentatively try to read in a UCN.
If the UCN is not syntactically well-formed, we fall back to the old
treatment: a backslash followed by an identifier beginning with 'u' (or 'U').
Because the spelling of an identifier with UCNs still has the UCN in it, we
need to convert that to UTF-8 in Preprocessor::LookUpIdentifierInfo.
Of course, valid code that does *not* use UCNs will see only a very minimal
performance hit (checks after each identifier for non-ASCII characters,
checks when converting raw_identifiers to identifiers that they do not
contain UCNs, and checks when getting the spelling of an identifier that it
does not contain a UCN).
This patch also adds basic support for actual UTF-8 in the source. This is
treated almost exactly the same as UCNs except that we consider stray
Unicode characters to be mistakes and offer a fixit to remove them.
llvm-svn: 173369
starting with an underscore is ill-formed.
Since this rule rejects programs that were using <inttypes.h>'s macros, recover
from this error by treating the ud-suffix as a separate preprocessing-token,
with a DefaultError ExtWarn. The approach of treating such cases as two tokens
is under discussion for standardization, but is in any case a conforming
extension and allows existing codebases to keep building while the committee
makes up its mind.
Reword the warning on the definition of literal operators not starting with
underscores (which are, strangely, legal) to more explicitly state that such
operators can't be called by literals. Remove the special-case diagnostic for
hexfloats, since it was both triggering in the wrong cases and incorrect.
llvm-svn: 152287
grammar requires a string-literal and not a user-defined-string-literal. The
two constructs are still represented by the same TokenKind, in order to prevent
a combinatorial explosion of different kinds of token. A flag on Token tracks
whether a ud-suffix is present, in order to prevent clients from needing to look
at the token's spelling.
llvm-svn: 152098
Douglas Gregor