test: add test for nil check / bounds check compiler confusion

This test started failing at CL 228106 and was fixed by CL 228677.

Fixes #38496

Change-Id: I2dadcd99227347e8d28179039f5f345e728c4595
Reviewed-on: https://go-review.googlesource.com/c/go/+/228698
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/test/fixedbugs/issue38496.go b/test/fixedbugs/issue38496.go
new file mode 100644
index 0000000000..717aa5d41d
--- /dev/null
+++ b/test/fixedbugs/issue38496.go
@@ -0,0 +1,20 @@
+// run
+
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Make sure bounds check elision isn't confused with nil check elision.
+
+package main
+
+func main() {
+	defer func() {
+		err := recover()
+		if err == nil {
+			panic("failed to check nil ptr")
+		}
+	}()
+	var m [2]*int
+	_ = *m[1] // need a nil check, but not a bounds check
+}