Implement most of N3638 (return type deduction for normal functions).

Missing (somewhat ironically) is support for the new deduction rules
in lambda functions, plus PCH support for return type patching.

llvm-svn: 181108

1 files changed, 26 insertions, 12 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index f4e53e61058..b827dc1080a 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -2036,6 +2036,16 @@ const FunctionType *ASTContext::adjustFunctionType(const FunctionType *T,
   return cast<FunctionType>(Result.getTypePtr());
 }
 
+void ASTContext::adjustDeducedFunctionResultType(FunctionDecl *FD,
+                                                 QualType ResultType) {
+  // FIXME: Need to inform serialization code about this!
+  for (FD = FD->getMostRecentDecl(); FD; FD = FD->getPreviousDecl()) {
+    const FunctionProtoType *FPT = FD->getType()->castAs<FunctionProtoType>();
+    FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
+    FD->setType(getFunctionType(ResultType, FPT->getArgTypes(), EPI));
+  }
+}
+
 /// getComplexType - Return the uniqued reference to the type for a complex
 /// number with the specified element type.
 QualType ASTContext::getComplexType(QualType T) const {
@@ -3564,18 +3574,20 @@ QualType ASTContext::getUnaryTransformType(QualType BaseType,
   return QualType(Ty, 0);
 }
 
-/// getAutoType - We only unique auto types after they've been deduced.
-QualType ASTContext::getAutoType(QualType DeducedType,
-                                 bool IsDecltypeAuto,
+/// getAutoType - Return the uniqued reference to the 'auto' type which has been
+/// deduced to the given type, or to the canonical undeduced 'auto' type, or the
+/// canonical deduced-but-dependent 'auto' type.
+QualType ASTContext::getAutoType(QualType DeducedType, bool IsDecltypeAuto,
                                  bool IsDependent) const {
+  if (DeducedType.isNull() && !IsDecltypeAuto && !IsDependent)
+    return getAutoDeductType();
+
+  // Look in the folding set for an existing type.
   void *InsertPos = 0;
-  if (!DeducedType.isNull()) {
-    // Look in the folding set for an existing type.
-    llvm::FoldingSetNodeID ID;
-    AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent);
-    if (AutoType *AT = AutoTypes.FindNodeOrInsertPos(ID, InsertPos))
-      return QualType(AT, 0);
-  }
+  llvm::FoldingSetNodeID ID;
+  AutoType::Profile(ID, DeducedType, IsDecltypeAuto, IsDependent);
+  if (AutoType *AT = AutoTypes.FindNodeOrInsertPos(ID, InsertPos))
+    return QualType(AT, 0);
 
   AutoType *AT = new (*this, TypeAlignment) AutoType(DeducedType,
                                                      IsDecltypeAuto,
@@ -3617,8 +3629,10 @@ QualType ASTContext::getAtomicType(QualType T) const {
 /// getAutoDeductType - Get type pattern for deducing against 'auto'.
 QualType ASTContext::getAutoDeductType() const {
   if (AutoDeductTy.isNull())
-    AutoDeductTy = getAutoType(QualType(), false);
-  assert(!AutoDeductTy.isNull() && "can't build 'auto' pattern");
+    AutoDeductTy = QualType(
+      new (*this, TypeAlignment) AutoType(QualType(), /*decltype(auto)*/false,
+                                          /*dependent*/false),
+      0);
   return AutoDeductTy;
 }