From 7f139d8103c432123ec62c7b74d04d4360c9c86b Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sun, 5 Jun 2011 05:14:41 +0000
Subject: [PATCH] Allow block returns in C++ with the form

  return <expression> ;

in blocks with a 'void' result type, so long as <expression> has type
'void'. This follows the rules for C++ functions.

llvm-svn: 132658
---
 clang/lib/Sema/SemaStmt.cpp     |  8 ++++++--
 clang/test/SemaObjCXX/blocks.mm | 26 ++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 1ecb4196b9d5..d3a22cdbb98c 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -1617,13 +1617,17 @@ Sema::ActOnBlockReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   // compatibility to worry about here.
   ReturnStmt *Result = 0;
   if (CurBlock->ReturnType->isVoidType()) {
-    if (RetValExp) {
+    if (RetValExp && !RetValExp->isTypeDependent() &&
+        (!getLangOptions().CPlusPlus || !RetValExp->getType()->isVoidType())) {
       Diag(ReturnLoc, diag::err_return_block_has_expr);
       RetValExp = 0;
     }
     Result = new (Context) ReturnStmt(ReturnLoc, RetValExp, 0);
   } else if (!RetValExp) {
-    return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
+    if (!CurBlock->ReturnType->isDependentType())
+      return StmtError(Diag(ReturnLoc, diag::err_block_return_missing_expr));
+
+    Result = new (Context) ReturnStmt(ReturnLoc, 0, 0);
   } else {
     const VarDecl *NRVOCandidate = 0;
 
diff --git a/clang/test/SemaObjCXX/blocks.mm b/clang/test/SemaObjCXX/blocks.mm
index 6c2343df0e09..c91fd103e133 100644
--- a/clang/test/SemaObjCXX/blocks.mm
+++ b/clang/test/SemaObjCXX/blocks.mm
@@ -118,3 +118,29 @@ void f(int (^bl)(A* a)); // expected-note {{candidate function not viable: no kn
 void g() {
   f(^(B* b) { return 0; }); // expected-error {{no matching function for call to 'f'}}
 }
+
+namespace DependentReturn {
+  template<typename T>
+  void f(T t) {
+    (void)^(T u) {
+      if (t != u)
+        return t + u;
+      else
+        return;
+    };
+
+    (void)^(T u) {
+      if (t == u)
+        return;
+      else
+        return t + u;
+    };
+  }
+
+  struct X { };
+  void operator+(X, X);
+  bool operator==(X, X);
+  bool operator!=(X, X);
+
+  template void f<X>(X);
+}