fmt: make type of fmt.Errorf the same as that of errors.New

This applies only for cases where %w is not used.

The purpose of this change is to reduce test failures where tests
depend on these two being the same type, as they previously were.

Change-Id: I2dd28b93fe1d59f3cfbb4eb0875d1fb8ee699746
Reviewed-on: https://go-review.googlesource.com/c/go/+/167402
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/fmt/errors_test.go b/src/fmt/errors_test.go
index a3cd26ef3e..ed77709ea0 100644
--- a/src/fmt/errors_test.go
+++ b/src/fmt/errors_test.go
@@ -378,6 +378,21 @@ func TestErrorFormatter(t *testing.T) {
 	}
 }
 
+func TestSameType(t *testing.T) {
+	err0 := errors.New("inner")
+	want := fmt.Sprintf("%T", err0)
+
+	err := fmt.Errorf("foo: %v", err0)
+	if got := fmt.Sprintf("%T", err); got != want {
+		t.Errorf("got %v; want %v", got, want)
+	}
+
+	err = fmt.Errorf("foo %s", "bar")
+	if got := fmt.Sprintf("%T", err); got != want {
+		t.Errorf("got %v; want %v", got, want)
+	}
+}
+
 var _ errors.Formatter = wrapped{}
 
 type wrapped struct {