[clang] Make handling of unnamed template params similar to function params

Summary:
Clang uses the location identifier should be inserted for declarator
decls when a decl is unnamed. But for type template and template template
paramaters it uses the location of "typename/class" keyword, which makes it hard
for tooling to insert/change parameter names.

This change tries to unify these two cases by making template parameter
parsing and sourcerange operations similar to function params/declarator decls.

Reviewers: ilya-biryukov

Subscribers: arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68143

llvm-svn: 373340

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 40c39c845db..c03ae22fb5d 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -510,8 +510,12 @@ SourceRange TemplateTypeParmDecl::getSourceRange() const {
   if (hasDefaultArgument() && !defaultArgumentWasInherited())
     return SourceRange(getBeginLoc(),
                        getDefaultArgumentInfo()->getTypeLoc().getEndLoc());
-  else
-    return TypeDecl::getSourceRange();
+  // TypeDecl::getSourceRange returns a range containing name location, which is
+  // wrong for unnamed template parameters. e.g:
+  // it will return <[[typename>]] instead of <[[typename]]>
+  else if (getDeclName().isEmpty())
+    return SourceRange(getBeginLoc());
+  return TypeDecl::getSourceRange();
 }
 
 unsigned TemplateTypeParmDecl::getDepth() const {