Add some text from the C++ standard and additional ambiguity resolution tests.

No funcitonality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@57136 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 7 deletions

diff --git a/lib/Parse/ParseTentative.cpp b/lib/Parse/ParseTentative.cpp
index 9bd35dd110..bd2d106923 100644
--- a/lib/Parse/ParseTentative.cpp
+++ b/lib/Parse/ParseTentative.cpp
@@ -282,16 +282,24 @@ bool Parser::isCXXConditionDeclaration() {
   return TPR == TPResult::True();
 }
 
-/// isCXXTypeIdInParens - Assumes that a '(' was parsed and now we want to

-/// know whether the parens contain an expression or a type-id.

-/// Returns true for a type-id and false for an expression.

-/// If during the disambiguation process a parsing error is encountered,

-/// the function returns true to let the declaration parsing code handle it.

-///

-/// type-id:

+/// isCXXTypeIdInParens - Assumes that a '(' was parsed and now we want to
+/// know whether the parens contain an expression or a type-id.
+/// Returns true for a type-id and false for an expression.
+/// If during the disambiguation process a parsing error is encountered,
+/// the function returns true to let the declaration parsing code handle it.
+///
+/// type-id:
 ///   type-specifier-seq abstract-declarator[opt]
 ///
 bool Parser::isCXXTypeIdInParens() {
+
+  // C++ 8.2p2:
+  // The ambiguity arising from the similarity between a function-style cast and
+  // a type-id can occur in different contexts. The ambiguity appears as a
+  // choice between a function-style cast expression and a declaration of a
+  // type. The resolution is that any construct that could possibly be a type-id
+  // in its syntactic context shall be considered a type-id.
+
   TPResult TPR = isCXXDeclarationSpecifier();
   if (TPR != TPResult::Ambiguous())
     return TPR != TPResult::False(); // Returns true for TPResult::True() or
@@ -706,6 +714,16 @@ Parser::TPResult Parser::TryParseDeclarationSpecifier() {
 ///         exception-specification[opt]
 ///
 bool Parser::isCXXFunctionDeclarator() {
+
+  // C++ 8.2p1:
+  // The ambiguity arising from the similarity between a function-style cast and
+  // a declaration mentioned in 6.8 can also occur in the context of a
+  // declaration. In that context, the choice is between a function declaration
+  // with a redundant set of parentheses around a parameter name and an object
+  // declaration with a function-style cast as the initializer. Just as for the
+  // ambiguities mentioned in 6.8, the resolution is to consider any construct
+  // that could possibly be a declaration a declaration.
+
   TentativeParsingAction PA(*this);
 
   ConsumeParen();