if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after ReadByte at EOF: got no error")
	}

	// check not at EOF
	b.WriteString("abcdefghijklmnopqrstuvwxyz")

	// after unsuccessful read
	if n, err := b.Read(nil); n != 0 || err != nil {
		t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
	}
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after Read(nil): got no error")
	}

// Copyright 2015 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 contains the majority of valid opcode combinations
// available in cmd/internal/obj/ppc64/asm9.go with
// their valid instruction encodings.

#include "../../../../../runtime/textflag.h"

// In case of index mode instructions, usage of
// (Rx)(R0) is equivalent to (Rx+R0)

API, and should be named after the issue number of the API proposal.
For example, if the directory `6-stdlib/99-minor` is present,
then an `api/next` file with the line

    pkg net/http, function F #12345

should have a corresponding file named `doc/next/6-stdlib/99-minor/net/http/12345.md`.
At a minimum, that file should contain either a full sentence or a TODO,
ideally referring to a person with the responsibility to complete the note.

<a href="#Predeclared_identifiers"><code>nil</code></a>;
that case is selected when the expression in the TypeSwitchGuard
is a <code>nil</code> interface value.
There may be at most one <code>nil</code> case.
</p>

<p>
Given an expression <code>x</code> of type <code>interface{}</code>,
the following type switch:
</p>

<pre>
switch i := x.(type) {
case nil:

#!/usr/bin/env bash
# Copyright 2015 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.

# Usage: buildall.bash [-e] [pattern]
#
# buildall.bash builds the standard library for all Go-supported
# architectures.
#
# Originally the Go build system used it as a smoke test to quickly
# flag portability issues in builders named "misc-compile" or "all-compile".

of Go in effect in the referring file. (The effective version is determined
by the `go` directive in the file's enclosing `go.mod` file, and
by any [`//go:build` constraints](https://pkg.go.dev/cmd/go#hdr-Build_constraints)
in the file.)

For example, it will report a diagnostic for a reference to the
`reflect.TypeFor` function (introduced in go1.22) from a file in a
module whose go.mod file specifies `go 1.21`.