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git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@60119 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/Parse/Parser.cpp b/lib/Parse/Parser.cpp
index ec07b42319..42d95e7f02 100644
--- a/lib/Parse/Parser.cpp
+++ b/lib/Parse/Parser.cpp
@@ -700,6 +700,15 @@ Parser::ExprResult Parser::ParseSimpleAsm() {
 /// This simplifies handling of C++ scope specifiers and allows efficient
 /// backtracking without the need to re-parse and resolve nested-names and
 /// typenames.
+/// It will mainly be called when we expect to treat identifiers as typenames
+/// (if they are typenames). For example, in C we do not expect identifiers
+/// inside expressions to be treated as typenames so it will not be called
+/// for expressions in C.
+/// The benefit for C/ObjC is that a typename will be annotated and
+/// Actions.isTypeName will not be needed to be called again (e.g. isTypeName
+/// will not be called twice, once to check whether we have a declaration
+/// specifier, and another one to get the actual type inside
+/// ParseDeclarationSpecifiers).
 void Parser::TryAnnotateTypeOrScopeToken() {
   if (Tok.is(tok::annot_qualtypename) || Tok.is(tok::annot_cxxscope))
     return;