Add custom callback object for typo correction in BuildRecoveryCallExpr.

The new callback, in addition to limiting which keywords to include in
the pool of typo correction candidates, also filters out non-keyword
candidates that don't refer to (template) functions that accept the
number of arguments that are present for the call being recovered.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148962 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed