An error on not-int-const:1 indicates that foo is not an integer constant.
An error on not-num-const:1 indicates that foo is not a number constant.
An error on not-str-lit:1 indicates that foo is not a string literal.
An error on not-signed-int-const:1 indicates that foo is not a signed integer constant.

The line number specifies the name involved. In the example, 1 is foo.

Next, cgo must learn the details of each type, variable, function, or

		rc, err = OpenReader(path)
		if err == nil {
			defer rc.Close()
			z = &rc.Reader
		}
		var err2 error
		raw, err2 = os.ReadFile(path)
		if err2 != nil {
			t.Errorf("ReadFile(%s) error=%v", path, err2)
			return
		}
	}
	if err != zt.Error {
		t.Errorf("error=%v, want %v", err, zt.Error)
		return
	}

	// bail if file is not zip
	if err == ErrFormat {
		return
	}

		switch err := recover().(type) {
		case nil:
			t.Fatal("bytes.Buffer.ReadFrom didn't panic")
		case error:
			// this is the error string of errNegativeRead
			wantError := "bytes.Buffer: reader returned negative count from Read"
			if err.Error() != wantError {
				t.Fatalf("recovered panic: got %v, want %v", err.Error(), wantError)
			}
		default:
			t.Fatalf("unexpected panic value: %#v", err)
		}
	}()

</p>

<h2 id="Errors">Errors</h2>

<p>
The predeclared type <code>error</code> is defined as
</p>

<pre>
type error interface {
	Error() string
}
</pre>

<p>
It is the conventional interface for representing an error condition,
with the nil value representing no error.
For instance, a function to read data from a file might be defined:
</p>

<pre>

	MOVBU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVHU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVWU	X5, (X6)			// ERROR "unsupported unsigned store"
	MOVF	F0, F1, F2			// ERROR "illegal MOV instruction"
	MOVD	F0, F1, F2			// ERROR "illegal MOV instruction"
	MOV	X10, X11, X12			// ERROR "illegal MOV instruction"
	MOVW	X10, X11, X12			// ERROR "illegal MOV instruction"

// and an error is returned explaining why.
//
// As a by-product of checking the fields, this function returns paxHdrs, which
// contain all fields that could not be directly encoded.
// A value receiver ensures that this method does not mutate the source Header.
func (h Header) allowedFormats() (format Format, paxHdrs map[string]string, err error) {
	format = FormatUSTAR | FormatPAX | FormatGNU

pkg syscall (windows-386), const WSAENOPROTOOPT = 10042 #62254
pkg syscall (windows-386), const WSAENOPROTOOPT Errno #62254
pkg syscall (windows-amd64), const WSAENOPROTOOPT = 10042 #62254

pkg archive/tar, type FileInfoNames interface { Gname, IsDir, ModTime, Mode, Name, Size, Sys, Uname } #50102
pkg archive/tar, type FileInfoNames interface, Gname() (string, error) #50102
pkg archive/tar, type FileInfoNames interface, IsDir() bool #50102
pkg archive/tar, type FileInfoNames interface, ModTime() time.Time #50102
pkg archive/tar, type FileInfoNames interface, Mode() fs.FileMode #50102
pkg archive/tar, type FileInfoNames interface, Name() string #50102

		usage()
	}

	var zb bytes.Buffer
	zw := zip.NewWriter(&zb)
	seen := make(map[string]bool)
	err := filepath.WalkDir(".", func(path string, d fs.DirEntry, err error) error {
		if d.IsDir() {
			return nil
		}
		data, err := os.ReadFile(path)
		if err != nil {
			log.Fatal(err)
		}
		if strings.HasSuffix(path, ".zip") {
			log.Fatalf("unexpected file during walk: %s", path)

[`x509usepolicies` setting.](/pkg/crypto/x509/#CreateCertificate).


### Go 1.21

Go 1.21 made it a run-time error to call `panic` with a nil interface value,
controlled by the [`panicnil` setting](/pkg/builtin/#panic).

Go 1.21 made it an error for html/template actions to appear inside of an ECMAScript 6
template literal, controlled by the