io: revert: add an Err field to LimitedReader

We are having a hard time deciding the exact semantics
of the Err field, and we need to ship the beta.
So revert the Err field change; it can wait for Go 1.20.

For #51115.

This reverts CL 396215.

Change-Id: I7719386567d3da10a614058a11f19dbccf304b4d
Reviewed-on: https://go-review.googlesource.com/c/go/+/410133
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Russ Cox <rsc@golang.org>

1 files changed, 0 insertions, 14 deletions

diff --git a/src/io/example_test.go b/src/io/example_test.go
index e4b20bd981..419e449982 100644
--- a/src/io/example_test.go
+++ b/src/io/example_test.go
@@ -6,7 +6,6 @@ package io_test
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -284,16 +283,3 @@ func ExampleReadAll() {
 	// Output:
 	// Go is a general-purpose language designed with systems programming in mind.
 }
-
-func ExampleLimitedReader() {
-	r := strings.NewReader("some io.Reader stream to be read\n")
-	sentinel := errors.New("reached read limit")
-	lr := &io.LimitedReader{R: r, N: 4, Err: sentinel}
-
-	if _, err := io.Copy(os.Stdout, lr); err != sentinel {
-		log.Fatal(err)
-	}
-
-	// Output:
-	// some
-}