DR1048: drop top-level cv-qualifiers when deducing the return type of a

lambda-expression in C++11, to match the C++14 rules.

llvm-svn: 224620

1 files changed, 7 insertions, 2 deletions

diff --git a/clang/lib/Sema/SemaLambda.cpp b/clang/lib/Sema/SemaLambda.cpp
index a64a0fb323d..90a81f4ec45 100644
--- a/clang/lib/Sema/SemaLambda.cpp
+++ b/clang/lib/Sema/SemaLambda.cpp
@@ -617,7 +617,7 @@ void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
   // If it was ever a placeholder, it had to been deduced to DependentTy.
   assert(CSI.ReturnType.isNull() || !CSI.ReturnType->isUndeducedType()); 
 
-  // C++ Core Issue #975, proposed resolution:
+  // C++ core issue 975:
   //   If a lambda-expression does not include a trailing-return-type,
   //   it is as if the trailing-return-type denotes the following type:
   //     - if there are no return statements in the compound-statement,
@@ -631,6 +631,10 @@ void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
   //       same, that common type;
   //     - otherwise, the program is ill-formed.
   //
+  // C++ core issue 1048 additionally removes top-level cv-qualifiers
+  // from the types of returned expressions to match the C++14 auto
+  // deduction rules.
+  //
   // In addition, in blocks in non-C++ modes, if all of the return
   // statements are enumerator-like expressions of some type T, where
   // T has a name for linkage, then we infer the return type of the
@@ -679,7 +683,8 @@ void Sema::deduceClosureReturnType(CapturingScopeInfo &CSI) {
     const ReturnStmt *RS = *I;
     const Expr *RetE = RS->getRetValue();
 
-    QualType ReturnType = (RetE ? RetE->getType() : Context.VoidTy);
+    QualType ReturnType =
+        (RetE ? RetE->getType() : Context.VoidTy).getUnqualifiedType();
     if (Context.hasSameType(ReturnType, CSI.ReturnType))
       continue;