+// Copyright 2019 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.
+
+// This file contains tests for the errorsas checker.
+
+package a
+
+import "errors"
+
+type myError int
+
+func (myError) Error() string { return "" }
+
+func perr() *error { return nil }
+
+type iface interface {
+ m()
+}
+
+func two() (error, interface{}) { return nil, nil }
+
+func _() {
+ var (
+ e error
+ m myError
+ i int
+ f iface
+ ei interface{}
+ )
+ errors.As(nil, &e) // *error
+ errors.As(nil, &m) // *T where T implemements error
+ errors.As(nil, &f) // *interface
+ errors.As(nil, perr()) // *error, via a call
+ errors.As(nil, ei) // empty interface
+
+ errors.As(nil, nil) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
+ errors.As(nil, e) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
+ errors.As(nil, m) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
+ errors.As(nil, f) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
+ errors.As(nil, &i) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
+ errors.As(two())
+}