From 4f53cbe431f529fc2bd62c2c8020791eb85d0d4d Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@apple.com>
Date: Wed, 4 May 2016 18:07:20 +0000
Subject: [PATCH] [ObjC] Enter a new evaluation context before calling
 BuildBlockForLambdaConversion.

Previously, clang would build an incorrect AST for the following code:

id test() {
  return @{@"a": [](){}, @"b": [](){}};
}

ReturnStmt 0x10d080448
`-ExprWithCleanups 0x10d080428
  |-cleanup Block 0x10d0801f0 // points to the second BlockDecl
    ...
    -BlockDecl 0x10d07f150 // First block
    ...
    -BlockDecl 0x10d0801f0 // Second block
    ...
     `-ExprWithCleanups 0x10d0801d0
       |-cleanup Block 0x10d07f150 // points to the first BlockDecl

To fix the bug, this commit enters a new evaluation context to reset
ExprNeedsCleanups before each block is parsed.

rdar://problem/16879958

Differential Revision: http://reviews.llvm.org/D18815


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@268527 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaExprCXX.cpp         |  3 +++
 test/SemaObjCXX/block-cleanup.mm | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 test/SemaObjCXX/block-cleanup.mm

diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 88f2bc798a..e11d9c84fe 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -6229,9 +6229,12 @@ ExprResult Sema::BuildCXXMemberCallExpr(Expr *E, NamedDecl *FoundDecl,
       // follows the normal lifetime rules for block literals instead of being
       // autoreleased.
       DiagnosticErrorTrap Trap(Diags);
+      PushExpressionEvaluationContext(PotentiallyEvaluated);
       ExprResult Exp = BuildBlockForLambdaConversion(E->getExprLoc(),
                                                      E->getExprLoc(),
                                                      Method, E);
+      PopExpressionEvaluationContext();
+
       if (Exp.isInvalid())
         Diag(E->getExprLoc(), diag::note_lambda_to_block_conv);
       return Exp;
diff --git a/test/SemaObjCXX/block-cleanup.mm b/test/SemaObjCXX/block-cleanup.mm
new file mode 100644
index 0000000000..0c6a6d8c26
--- /dev/null
+++ b/test/SemaObjCXX/block-cleanup.mm
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.11.0 -std=gnu++11 -o /dev/null -x objective-c++ -fblocks -ast-dump %s 2>&1 | FileCheck %s
+
+// CHECK:      -FunctionDecl {{.*}} test 'id (void)'
+// CHECK-NEXT:   -CompoundStmt
+// CHECK-NEXT:     -ReturnStmt
+// CHECK-NEXT:       -ExprWithCleanups
+// CHECK-NEXT:         -cleanup Block
+// CHECK-NEXT:         -cleanup Block
+
+@interface NSDictionary
++ (id)dictionaryWithObjects:(const id [])objects forKeys:(const id [])keys count:(unsigned long)cnt;
+@end
+
+id test() {
+  return @{@"a": [](){}, @"b": [](){}};
+}
-- 
2.50.1