string values from Go to C and back to Go.

Using //export in a file places a restriction on the preamble:
since it is copied into two different C output files, it must not
contain any definitions, only declarations. If a file contains both
definitions and declarations, then the two output files will produce
duplicate symbols and the linker will fail. To avoid this, definitions

</p>
<ul>
	<li>
	If <code>S</code> contains an embedded field <code>T</code>,
	the <a href="#Method_sets">method sets</a> of <code>S</code>
	and <code>*S</code> both include promoted methods with receiver
	<code>T</code>. The method set of <code>*S</code> also
	includes promoted methods with receiver <code>*T</code>.
	</li>

	<li>
	If <code>S</code> contains an embedded field <code>*T</code>,

	w := NewWalker(context, context.Dir)
	for _, pkg := range w.stdPackages {
		if strings.HasPrefix(pkg, "vendor/") || strings.HasPrefix(pkg, "golang.org/x/") {
			t.Fatalf("stdPackages contains unexpected package %s", pkg)
		}
	}
}

func TestIssue64958(t *testing.T) {
	defer func() {
		if x := recover(); x != nil {
			t.Errorf("expected no panic; recovered %v", x)
		}
	}()

	b := rZipBytes()
	return bytes.NewReader(b), int64(len(b))
}

// biggestZipBytes returns the bytes of a zip file biggest.zip
// that contains a zip file bigger.zip that contains a zip file
// big.zip that contains big.file, which contains 2³²-1 zeros.
// The big.zip file is interesting because it has no zip64 header,
// much like the innermost zip files in the well-known 42.zip.
//

					if strings.ContainsAny(abspath, "\r\n") {
						// This should have been checked when the file path was first resolved,
						// but we double check here just to be sure.
						fatalf("internal error: ParseGo: abspath contains unexpected newline character: %q", abspath)
					}
					f.Preamble += fmt.Sprintf("#line %d %q\n", sourceLine(cg), abspath)
					f.Preamble += commentText(cg) + "\n"
					f.Preamble += "#line 1 \"cgo-generated-wrapper\"\n"

			addr := obj.Addr{}
			parser.operand(&addr)
		})

		switch {
		case err == nil:
			t.Errorf("fail at %s: got no errors; expected %s\n", test.input, test.error)
		case !strings.Contains(err.Error(), test.error):
			t.Errorf("fail at %s: got %s; expected %s", test.input, err, test.error)
		}
	}
}

func testOperandParser(t *testing.T, parser *Parser, tests []operandTest) {

	b := NewReader(new(negativeReader))
	defer func() {
		switch err := recover().(type) {
		case nil:
			t.Fatal("read did not panic")
		case error:
			if !strings.Contains(err.Error(), "reader returned negative count from Read") {
				t.Fatalf("wrong panic: %v", err)
			}
		default:
			t.Fatalf("unexpected panic value: %T(%v)", err, err)
		}
	}()

// forces us to be a more liberal.
// Thus, we only reject all keys with NUL, and only reject NULs in values
// for the PAX version of the USTAR string fields.
// The key must not contain an '=' character.
func validPAXRecord(k, v string) bool {
	if k == "" || strings.Contains(k, "=") {
		return false
	}
	switch k {
	case paxPath, paxLinkpath, paxUname, paxGname:
		return !hasNUL(v)
	default:
		return !hasNUL(k)
	}

	ErrInsecurePath    = errors.New("archive/tar: insecure file path")
	errMissData        = errors.New("archive/tar: sparse file references non-existent data")
	errUnrefData       = errors.New("archive/tar: sparse file contains unreferenced data")
	errWriteHole       = errors.New("archive/tar: write non-NUL byte in sparse hole")
)

type headerError []string

func (he headerError) Error() string {

		// to where the expansion occurs. We care about where
		// the expansion occurs, so in that case treat the note
		// as an error.
		isError := strings.Contains(line, ": error:")
		isErrorNote := strings.Contains(line, ": note:") && sawUnmatchedErrors
		if !isError && !isErrorNote {
			continue
		}

		c1 := strings.Index(line, ":")
		if c1 < 0 {
			continue
		}