Implement ES6 completion semantics (--harmony-completion).

test/mjsunit/harmony/completion.js

+// 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.
+
+// Flags: --harmony-completion
+
+
+function assertUndef(x) {
+  assertEquals(undefined, x);
+}
+
+
+// IfStatement [13.6.7]
+assertUndef(eval('42; if (true) ; else 0;'));  // ES5: 42
+assertUndef(eval('42; if (true) ;'));  // ES5: 42
+assertUndef(eval('42; if (false) 0;'));  // ES5: 42
+
+
+// IterationStatement [13.7] (a few of them)
+assertUndef(eval('42; do ; while (false);'));  // ES5: 42
+assertUndef(eval('42; var x = 1; do ; while (x--);'));  // ES5: 42
+assertUndef(eval('42; while (false) 0;'));  // ES5: 42
+assertUndef(eval('42; while (true) break;'));  // ES5: 42
+assertUndef(eval('42; var x = 1; while (x--) ;'));  // ES5: 42
+assertUndef(eval('42; for (; false; ) 0;'));  // ES5: 42
+assertUndef(eval('42; for (var x = 1; x; x--) ;'));  // ES5: 42
+
+
+// WithStatement [13.11.7]
+assertUndef(eval('42; with ({}) ;'));  // ES5: 42
+
+
+// SwitchStatement [13.12.11]
+assertUndef(eval('42; switch (0) {};'));  // ES5: 42
+assertUndef(eval('42; switch (0) { case 1: 1; };'));  // ES5: 42
+assertUndef(eval('42; switch (0) { case 0: ; };'));  // ES5: 42
+assertUndef(eval('42; switch (0) { default: ; };'));  // ES5: 42
+assertUndef(eval('42; switch (0) { case 0: break; }'));  // ES5: 42
+assertEquals(0, eval('42; switch (0) { case 0: 0; }'));
+assertEquals(0, eval('42; switch (0) { case 0: 0; break; }'));
+
+
+// TryStatement [13.15.8]
+assertUndef(eval('42; try { } catch(e) { };'));  // ES5: 42
+assertUndef(eval('42; try { } catch(e) { 0; };'));  // ES5: 42
+assertUndef(eval('42; try { throw Error } catch(e) { };'));  // ES5: 42
+assertUndef(eval('42; try { throw Error } catch(e) { } finally { };'));  // ES5: 42
+
+
+// Some combinations
+assertUndef(eval('42; switch (0) { case 0: if (true) break; }'));  // ES5: 42
+assertUndef(eval('42; switch (0) { case 0: 0; if (true) ; }'));  // ES5: 0
+assertUndef(eval('42; switch (0) { case 0: 0; try { break } catch(e) { }; }'));  // ES5: 0
+
+// The following is not what ES6 says, but see ES bug 4540.
+assertUndef(eval('42; switch (0) { case 0: 0; if (true) break; }'));  // ES5: 0