Add the check name to the clang-tidy diagnostic output.

Summary:
Pass check names all the way from ClangTidyModule through
ClangTidyCheck and ClangTidyContext to ClangTidyError, and output it in
handleErrors. This allows to find mis-behaving check and disable it easily.

Reviewers: djasper, klimek

Reviewed By: djasper

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2534

llvm-svn: 199094
diff --git a/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp b/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
index bf1e3e3..8b25d02 100644
--- a/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/google/GoogleTidyModule.cpp
@@ -35,7 +35,7 @@
   if (!Ctor->isExplicit() && !Ctor->isImplicit() && Ctor->getNumParams() >= 1 &&
       Ctor->getMinRequiredArguments() <= 1) {
     SourceLocation Loc = Ctor->getLocation();
-    Context->Diag(Loc, "Single-argument constructors must be explicit")
+    diag(Loc, "Single-argument constructors must be explicit")
         << FixItHint::CreateInsertion(Loc, "explicit ");
   }
 }