[PATCH] D45383: Limit types of builtins that can be redeclared.

[Eli Friedman via Phabricator via cfe-commits]

efriedma added a comment.

We can could add an exception to the "don't allow redeclarations with custom type-checking" rule to specifically allow redeclaring `__va_start`.  The general rule is that we don't want user code redeclaring them because they don't have a specific signature, so our internal representation could change between releases.  But `__va_start` has a specific fixed signature from the Microsoft SDK headers, so it should be fine to allow redeclaring it without a warning.


https://reviews.llvm.org/D45383