After this, NUMERIC_CONSTANT and strings should parse only one way.
There are 8 types of literals, and 24 valid (literal, TokenKind) pairs.
This means adding 8 new named guards (or 24, if we want to assert the token).
It seems fairly clear to me at this point that the guard names are unneccesary
indirection: the guards are in fact coupled to the rule signature.
(Also add the zero guard I forgot in the previous patch.)
Differential Revision: https://reviews.llvm.org/D130066
This isn't allowed by the standard grammar but is allowed in C, and clang/GCC
permit it as an extension.
It avoids the need to determine which type of list we have in error-recovery.
While here, also support array index designators `{ [4]=1 }` which are
also legal in C, and common extensions in C++.
Differential Revision: https://reviews.llvm.org/D128687
Sam McCall