From 6773e2961de8f9e588cbf0e939ab3f325dd6fef9 Mon Sep 17 00:00:00 2001
From: littledan <littledan@chromium.org>
Date: Fri, 28 Aug 2015 15:43:00 -0700
Subject: [PATCH] Propagate switch statement value for 'eval'

This patch changes the switch scope desugaring to create blocks which
propagate their 'return value' for eval.

BUG=v8:4399
R=adamk
LOG=Y

Review URL: https://codereview.chromium.org/1309303006

Cr-Commit-Position: refs/heads/master@{#30454}
---
 src/parser.cc                              | 13 +++++++++++--
 test/cctest/test-ast-expression-visitor.cc |  1 +
 test/mjsunit/regress/regress-4399.js       | 17 +++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 test/mjsunit/regress/regress-4399.js

diff --git a/src/parser.cc b/src/parser.cc
index a357aa177..43694df11 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -2987,7 +2987,7 @@ Statement* Parser::ParseSwitchStatement(ZoneList<const AstRawString*>* labels,
   // }
 
   Block* switch_block =
-      factory()->NewBlock(NULL, 2, true, RelocInfo::kNoPosition);
+      factory()->NewBlock(NULL, 2, false, RelocInfo::kNoPosition);
   int switch_pos = peek_position();
 
   Expect(Token::SWITCH, CHECK_OK);
@@ -3004,8 +3004,17 @@ Statement* Parser::ParseSwitchStatement(ZoneList<const AstRawString*>* labels,
       factory()->NewExpressionStatement(tag_assign, RelocInfo::kNoPosition);
   switch_block->AddStatement(tag_statement, zone());
 
+  // make statement: undefined;
+  // This is needed so the tag isn't returned as the value, in case the switch
+  // statements don't have a value.
+  switch_block->AddStatement(
+      factory()->NewExpressionStatement(
+          factory()->NewUndefinedLiteral(RelocInfo::kNoPosition),
+          RelocInfo::kNoPosition),
+      zone());
+
   Block* cases_block =
-      factory()->NewBlock(NULL, 1, true, RelocInfo::kNoPosition);
+      factory()->NewBlock(NULL, 1, false, RelocInfo::kNoPosition);
   Scope* cases_scope = NewScope(scope_, BLOCK_SCOPE);
   cases_scope->SetNonlinear();
 
diff --git a/test/cctest/test-ast-expression-visitor.cc b/test/cctest/test-ast-expression-visitor.cc
index c7ef3605f..f4c1028ab 100644
--- a/test/cctest/test-ast-expression-visitor.cc
+++ b/test/cctest/test-ast-expression-visitor.cc
@@ -303,6 +303,7 @@ TEST(VisitSwitchStatment) {
         CHECK_VAR(.switch_tag, DEFAULT_TYPE);
         CHECK_EXPR(Literal, DEFAULT_TYPE);
       }
+      CHECK_EXPR(Literal, DEFAULT_TYPE);
       CHECK_VAR(.switch_tag, DEFAULT_TYPE);
       CHECK_EXPR(Literal, DEFAULT_TYPE);
     }
diff --git a/test/mjsunit/regress/regress-4399.js b/test/mjsunit/regress/regress-4399.js
new file mode 100644
index 000000000..c76c0c83b
--- /dev/null
+++ b/test/mjsunit/regress/regress-4399.js
@@ -0,0 +1,17 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Test that switch has the appropriate 'eval' value
+
+assertEquals("foo", eval('switch(1) { case 1: "foo" }'));
+assertEquals("foo", eval('{ switch(1) { case 1: "foo" } }'));
+assertEquals("foo", eval('switch(1) { case 1: { "foo" } }'));
+assertEquals("foo", eval('switch(1) { case 1: "foo"; break; case 2: "bar"; break }'));
+assertEquals("bar", eval('switch(2) { case 1: "foo"; break; case 2: "bar"; break }'));
+assertEquals("bar", eval('switch(1) { case 1: "foo"; case 2: "bar"; break }'));
+
+// The tag is not the value, if there's no value
+
+assertEquals(undefined, eval('switch (1) {}'));
+assertEquals(undefined, eval('switch (1) { case 1: {} }'));
-- 
2.34.1