Within the body of a lambda expression, decltype((x)) for an

id-expression 'x' will compute the type based on the assumption that
'x' will be captured, even if it isn't captured, per C++11
[expr.prim.lambda]p18. There are two related refactors that go into
implementing this:

  1) Split out the check that determines whether we should capture a
  particular variable reference, along with the computation of the
  type of the field, from the actual act of capturing the
  variable. 
  2) Always compute the result of decltype() within Sema, rather than
  AST, because the decltype() computation is now context-sensitive.

llvm-svn: 150347

2 files changed, 8 insertions, 35 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index bb93a68d265..cc651f9c9c5 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -2913,44 +2913,13 @@ QualType ASTContext::getTypeOfType(QualType tofType) const {
   return QualType(tot, 0);
 }
 
-/// getDecltypeForExpr - Given an expr, will return the decltype for that
-/// expression, according to the rules in C++0x [dcl.type.simple]p4
-static QualType getDecltypeForExpr(const Expr *e, const ASTContext &Context) {
-  if (e->isTypeDependent())
-    return Context.DependentTy;
-
-  // If e is an id expression or a class member access, decltype(e) is defined
-  // as the type of the entity named by e.
-  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(e)) {
-    if (const ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl()))
-      return VD->getType();
-  }
-  if (const MemberExpr *ME = dyn_cast<MemberExpr>(e)) {
-    if (const FieldDecl *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()))
-      return FD->getType();
-  }
-  // If e is a function call or an invocation of an overloaded operator,
-  // (parentheses around e are ignored), decltype(e) is defined as the
-  // return type of that function.
-  if (const CallExpr *CE = dyn_cast<CallExpr>(e->IgnoreParens()))
-    return CE->getCallReturnType();
-
-  QualType T = e->getType();
-
-  // Otherwise, where T is the type of e, if e is an lvalue, decltype(e) is
-  // defined as T&, otherwise decltype(e) is defined as T.
-  if (e->isLValue())
-    T = Context.getLValueReferenceType(T);
-
-  return T;
-}
 
 /// getDecltypeType -  Unlike many "get<Type>" functions, we don't unique
 /// DecltypeType AST's. The only motivation to unique these nodes would be
 /// memory savings. Since decltype(t) is fairly uncommon, space shouldn't be
 /// an issue. This doesn't effect the type checker, since it operates
 /// on canonical types (which are always unique).
-QualType ASTContext::getDecltypeType(Expr *e) const {
+QualType ASTContext::getDecltypeType(Expr *e, QualType UnderlyingType) const {
   DecltypeType *dt;
   
   // C++0x [temp.type]p2:
@@ -2976,8 +2945,8 @@ QualType ASTContext::getDecltypeType(Expr *e) const {
       dt = Canon;
     }
   } else {
-    QualType T = getDecltypeForExpr(e, *this);
-    dt = new (*this, TypeAlignment) DecltypeType(e, T, getCanonicalType(T));
+    dt = new (*this, TypeAlignment) DecltypeType(e, UnderlyingType, 
+                                      getCanonicalType(UnderlyingType));
   }
   Types.push_back(dt);
   return QualType(dt, 0);
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 556f97d8582..e15bac0b447 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1581,7 +1581,11 @@ QualType ASTNodeImporter::VisitDecltypeType(const DecltypeType *T) {
   if (!ToExpr)
     return QualType();
   
-  return Importer.getToContext().getDecltypeType(ToExpr);
+  QualType UnderlyingType = Importer.Import(T->getUnderlyingType());
+  if (UnderlyingType.isNull())
+    return QualType();
+
+  return Importer.getToContext().getDecltypeType(ToExpr, UnderlyingType);
 }
 
 QualType ASTNodeImporter::VisitUnaryTransformType(const UnaryTransformType *T) {