go code: replace closed(c) with x, ok := <-c

R=golang-dev, rog, bradfitzwork, r
CC=golang-dev
https://golang.org/cl/4243072

2 files changed, 24 insertions, 11 deletions

diff --git a/test/chan/perm.go b/test/chan/perm.go
index c725829d13..038ff94e36 100644
--- a/test/chan/perm.go
+++ b/test/chan/perm.go
@@ -22,21 +22,18 @@ func main() {
 
 	c <- 0 // ok
 	<-c    // ok
-	//TODO(rsc): uncomment when this syntax is valid for receive+check closed
-	//	x, ok := <-c	// ok
-	//	_, _ = x, ok
+	x, ok := <-c	// ok
+	_, _ = x, ok
 
 	cr <- 0 // ERROR "send"
 	<-cr    // ok
-	//TODO(rsc): uncomment when this syntax is valid for receive+check closed
-	//	x, ok = <-cr	// ok
-	//	_, _ = x, ok
+	x, ok = <-cr	// ok
+	_, _ = x, ok
 
 	cs <- 0 // ok
 	<-cs    // ERROR "receive"
-	////TODO(rsc): uncomment when this syntax is valid for receive+check closed
-	////	x, ok = <-cs	// ERROR "receive"
-	////	_, _ = x, ok
+	x, ok = <-cs	// ERROR "receive"
+	_, _ = x, ok
 
 	select {
 	case c <- 0: // ok
diff --git a/test/chan/select3.go b/test/chan/select3.go
index 47941063c0..b4e8f8e4bf 100644
--- a/test/chan/select3.go
+++ b/test/chan/select3.go
@@ -88,12 +88,16 @@ func main() {
 		ch <- 7
 	})
 
-	// receiving (a small number of times) from a closed channel never blocks
+	// receiving from a closed channel never blocks
 	testBlock(never, func() {
 		for i := 0; i < 10; i++ {
 			if <-closedch != 0 {
 				panic("expected zero value when reading from closed channel")
 			}
+			if x, ok := <-closedch; x != 0 || ok {
+				println("closedch:", x, ok)
+				panic("expected 0, false from closed channel")
+			}
 		}
 	})
 
@@ -191,12 +195,24 @@ func main() {
 		case <-closedch:
 		}
 	})
+	testBlock(never, func() {
+		select {
+		case x := <-closedch:
+			_ = x
+		}
+	})
+	testBlock(never, func() {
+		select {
+		case x, ok := <-closedch:
+			_, _ = x, ok
+		}
+	})
 	testPanic(always, func() {
 		select {
 		case closedch <- 7:
 		}
 	})
-	
+
 	// select should not get confused if it sees itself
 	testBlock(always, func() {
 		c := make(chan int)