Allow yield expressions without a RHS.

test/mjsunit/harmony/generators-parsing.js

Index: test/mjsunit/harmony/generators-parsing.js
diff --git a/test/mjsunit/harmony/generators-parsing.js b/test/mjsunit/harmony/generators-parsing.js
index 2a4a68c37cd3f71089c280d8b52dbe507b0f6fda..21790b0e1383b0a67dac5774a605b4c8d9916fab 100644
--- a/test/mjsunit/harmony/generators-parsing.js
+++ b/test/mjsunit/harmony/generators-parsing.js
@@ -35,6 +35,40 @@ function* g() { yield 3; yield 4; }
 // Yield expressions.
 function* g() { (yield 3) + (yield 4); }
 
+// Yield without a RHS.
+function* g() { yield; }

[marja, 2014/06/26 10:41:52]

Could you add a test that calls this kind of function (which has yield without a
value) and assert that the right thing is yielded? (What is the right thing in
this case?)

[wingo, 2014/06/26 11:04:27]

You can see an example of this on line 63.  (The right thing is
{value:undefined, done:false}.)

+function* g() { yield }
+function* g() {
+  yield
+}
+function* g() { (yield) }
+function* g() { [yield] }
+function* g() { {yield} }
+function* g() { yield, yield }
+function* g() { yield; yield }
+function* g() { (yield) ? yield : yield }
+function* g() {
+  (yield)
+  ? yield
+  : yield
+}
+
+// If yield has a RHS, it needs to start on the same line.  The * in a
+// yield* counts as starting the RHS.
+function* g() {
+  yield *
+  foo
+}
+assertThrows("function* g() { yield\n* foo }", SyntaxError);
+assertEquals(undefined,
+             (function*(){
+               yield
+               3
+             })().next().value);
+
+// A YieldExpression is not a LogicalORExpression.
+assertThrows("function* g() { yield ? yield : yield }", SyntaxError);
+
 // You can have a generator in strict mode.
 function* g() { "use strict"; yield 3; yield 4; }
 
@@ -50,14 +84,10 @@ function* g() { yield 1; return 2; yield "dead"; }
 // Named generator expression.
 (function* g() { yield 3; });
 
-// A generator without a yield is specified as causing an early error.  This
-// behavior is currently unimplemented.  See
-// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
+// You can have a generator without a yield.
 function* g() { }
 
-// A YieldExpression in the RHS of a YieldExpression is currently specified as
-// causing an early error.  This behavior is currently unimplemented.  See
-// https://bugs.ecmascript.org/show_bug.cgi?id=1283.
+// A YieldExpression is valid as the RHS of a YieldExpression.
 function* g() { yield yield 1; }
 function* g() { yield 3 + (yield 4); }
 
@@ -86,9 +116,6 @@ assertThrows("function* g() { yield: 1 }", SyntaxError)
 // functions.
 function* g() { function f() { yield (yield + yield (0)); } }
 
-// Yield needs a RHS.
-assertThrows("function* g() { yield; }", SyntaxError);
-
 // Yield in a generator is not an identifier.
 assertThrows("function* g() { yield = 10; }", SyntaxError);