Implement the Microsoft __is_convertible_to type trait, modeling the
semantics after the C++0x is_convertible type trait. This
implementation is not 100% complete, because it allows access errors
to be hard errors (rather than just evaluating false).

Original patch by Steven Watanabe!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@124425 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index 67351f7..5928871 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -537,8 +537,9 @@
 ///                   '__is_polymorphic'
 ///                   '__is_union'
 ///
-/// [GNU] binary-type-trait:
-///                   '__is_base_of'                          [TODO]
+///       binary-type-trait:
+/// [GNU]             '__is_base_of'       
+/// [MS]              '__is_convertible_to'
 ///
 ExprResult Parser::ParseCastExpression(bool isUnaryExpression,
                                        bool isAddressOfOperand,
@@ -988,6 +989,7 @@
 
   case tok::kw___builtin_types_compatible_p:
   case tok::kw___is_base_of:
+  case tok::kw___is_convertible_to:
     return ParseBinaryTypeTrait();
 
   case tok::at: {
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index 5a16729..e769eca 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -1828,6 +1828,7 @@
   default: llvm_unreachable("Not a known binary type trait");
   case tok::kw___is_base_of:                 return BTT_IsBaseOf;
   case tok::kw___builtin_types_compatible_p: return BTT_TypeCompatible;
+  case tok::kw___is_convertible_to:          return BTT_IsConvertibleTo;
   }
 }
 
diff --git a/lib/Parse/ParseTentative.cpp b/lib/Parse/ParseTentative.cpp
index 35d7254..a603c37 100644
--- a/lib/Parse/ParseTentative.cpp
+++ b/lib/Parse/ParseTentative.cpp
@@ -655,6 +655,7 @@
   case tok::kw___is_abstract:
   case tok::kw___is_base_of:
   case tok::kw___is_class:
+  case tok::kw___is_convertible_to:
   case tok::kw___is_empty:
   case tok::kw___is_enum:
   case tok::kw___is_pod: