Sema: Use the right type for PredefinedExpr when it's in a lambda.

1. We now print the return type of lambdas and return type deduced functions
as "auto". Trailing return types with decltype print the underlying type.
2. Use the lambda or block scope for the PredefinedExpr type instead of the
parent function. This fixes PR16946, a strange mismatch between type of the
expression and the actual result.
3. Verify the type in CodeGen.
4. The type for blocks is still wrong. They are numbered and the name is not
known until CodeGen.

llvm-svn: 188900

1 files changed, 12 insertions, 1 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 6a1e500d330..c2bbda33433 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -585,7 +585,18 @@ std::string PredefinedExpr::ComputeName(IdentType IT, const Decl *CurrentDecl) {
 
     POut.flush();
 
-    if (!isa<CXXConstructorDecl>(FD) && !isa<CXXDestructorDecl>(FD))
+    // Print "auto" for all deduced return types. This includes C++1y return
+    // type deduction and lambdas. For trailing return types resolve the
+    // decltype expression. Otherwise print the real type when this is
+    // not a constructor or destructor.
+    if ((isa<CXXMethodDecl>(FD) &&
+         cast<CXXMethodDecl>(FD)->getParent()->isLambda()) ||
+        (FT && FT->getResultType()->getAs<AutoType>()))
+      Proto = "auto " + Proto;
+    else if (FT && FT->getResultType()->getAs<DecltypeType>())
+      FT->getResultType()->getAs<DecltypeType>()->getUnderlyingType()
+          .getAsStringInternal(Proto, Policy);
+    else if (!isa<CXXConstructorDecl>(FD) && !isa<CXXDestructorDecl>(FD))
       AFT->getResultType().getAsStringInternal(Proto, Policy);
 
     Out << Proto;