Introduce the notion of instantiation dependence into Clang's AST. A

type/expression/template argument/etc. is instantiation-dependent if
it somehow involves a template parameter, even if it doesn't meet the
requirements for the more common kinds of dependence (dependent type,
type-dependent expression, value-dependent expression).

When we see an instantiation-dependent type, we know we always need to
perform substitution into that instantiation-dependent type. This
keeps us from short-circuiting evaluation in places where we
shouldn't, and lets us properly implement C++0x [temp.type]p2.

In theory, this would also allow us to properly mangle
instantiation-dependent-but-not-dependent decltype types per the
Itanium C++ ABI, but we aren't quite there because we still mangle
based on the canonical type in cases like, e.g.,

  template<unsigned> struct A { };
  template<typename T>
    void f(A<sizeof(sizeof(decltype(T() + T())))>) { }
  template void f<int>(A<sizeof(sizeof(int))>);

and therefore get the wrong answer.

llvm-svn: 134225

1 files changed, 22 insertions, 0 deletions

diff --git a/clang/lib/AST/DeclarationName.cpp b/clang/lib/AST/DeclarationName.cpp
index cef54e97c93..72c0e9da7f1 100644
--- a/clang/lib/AST/DeclarationName.cpp
+++ b/clang/lib/AST/DeclarationName.cpp
@@ -533,6 +533,28 @@ bool DeclarationNameInfo::containsUnexpandedParameterPack() const {
   llvm_unreachable("All name kinds handled.");
 }
 
+bool DeclarationNameInfo::isInstantiationDependent() const {
+  switch (Name.getNameKind()) {
+  case DeclarationName::Identifier:
+  case DeclarationName::ObjCZeroArgSelector:
+  case DeclarationName::ObjCOneArgSelector:
+  case DeclarationName::ObjCMultiArgSelector:
+  case DeclarationName::CXXOperatorName:
+  case DeclarationName::CXXLiteralOperatorName:
+  case DeclarationName::CXXUsingDirective:
+    return false;
+    
+  case DeclarationName::CXXConstructorName:
+  case DeclarationName::CXXDestructorName:
+  case DeclarationName::CXXConversionFunctionName:
+    if (TypeSourceInfo *TInfo = LocInfo.NamedType.TInfo)
+      return TInfo->getType()->isInstantiationDependentType();
+    
+    return Name.getCXXNameType()->isInstantiationDependentType();
+  }
+  llvm_unreachable("All name kinds handled.");
+}
+
 std::string DeclarationNameInfo::getAsString() const {
   std::string Result;
   llvm::raw_string_ostream OS(Result);