test/nilptr: add more tests

These tests were suggested in golang.org/issue/6080.
They were fixed as part of the new nil pointer checks
that I added a few weeks ago.

Recording the tests as part of marking the issue closed.

Fixes #6080.

R=golang-dev, r, bradfitz
CC=golang-dev
https://golang.org/cl/13255049

test/nilptr.go

@@ -40,6 +40,10 @@ func main() {
 	shouldPanic(p10)
 	shouldPanic(p11)
 	shouldPanic(p12)
+	shouldPanic(p13)
+	shouldPanic(p14)
+	shouldPanic(p15)
+	shouldPanic(p16)
 }
 
 func shouldPanic(f func()) {
@@ -152,3 +156,27 @@ func p12() {
 	var p *T = nil
 	println(*(&((*p).i)))
 }
+
+// Tests suggested in golang.org/issue/6080.
+
+func p13() {
+	var x *[10]int
+	y := x[:]
+	_ = y
+}
+
+func p14() {
+	println((*[1]int)(nil)[:])
+}
+
+func p15() {
+	for i := range (*[1]int)(nil)[:] {
+		_ = i
+	}
+}
+
+func p16() {
+	for i, v := range (*[1]int)(nil)[:] {
+		_ = i + v
+	}
+}