Re-enable format string warnings on printf.
The warnings are still incomplete. Apparently it is undefined to use a
vector specifier without a length modifier, which is not currently
warned on. Additionally, type warnings appear to not be working with
the hh modifier, and aren't warning on all of the special restrictions
from c99 printf.
llvm-svn: 352540
This reverts r348083. This was based on a misreading of the spec
for printf specifiers.
Also revert r343653, as without a subsequent patch, a correctly
specified format for a vector will incorrectly warn.
Fixes bug 40491.
llvm-svn: 352539
Sven van Haastregt