reflect: panic if ArrayOf is called with negative length

Since we cannot change the signature of reflect.ArrayOf to return an
error, we panic instead of producing a wrong result.

Fixes #43603

Change-Id: I23915df8d190f35af4d00ab86768868cd621e839
Reviewed-on: https://go-review.googlesource.com/c/go/+/284136
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/reflect/all_test.go b/src/reflect/all_test.go
index 35cc469d74..accda7fa74 100644
--- a/src/reflect/all_test.go
+++ b/src/reflect/all_test.go
@@ -4636,6 +4636,14 @@ func TestArrayOfDirectIface(t *testing.T) {
 	}
 }
 
+// Ensure passing in negative lengths panics.
+// See https://golang.org/issue/43603
+func TestArrayOfPanicOnNegativeLength(t *testing.T) {
+	shouldPanic("reflect: negative length passed to ArrayOf", func() {
+		ArrayOf(-1, TypeOf(byte(0)))
+	})
+}
+
 func TestSliceOf(t *testing.T) {
 	// check construction and use of type not in binary
 	type T int