The [RuneLen] function returns the number of 16-bit words in
the UTF-16 encoding of the rune. It returns -1 if the rune

\n   U+000A line feed or newline
\r   U+000D carriage return
\t   U+0009 horizontal tab
\v   U+000B vertical tab
\\   U+005C backslash
\'   U+0027 single quote  (valid escape only within rune literals)
\"   U+0022 double quote  (valid escape only within string literals)
</pre>

<p>
An unrecognized character following a backslash in a rune literal is illegal.
</p>

<pre class="ebnf">

	}
	testValidHeader(&h, t)
}

// Issue 4393. It is valid to have an extra data header
// which contains no body.
func TestZeroLengthHeader(t *testing.T) {
	h := FileHeader{
		Name:   "extadata.txt",
		Method: Deflate,
		Extra: []byte{

</p>

<h2 id="badcompiler">Incorrect compilation</h2>

<p>
The Go memory model restricts compiler optimizations as much as it does Go programs.
Some compiler optimizations that would be valid in single-threaded programs are not valid in all Go programs.
In particular, a compiler must not introduce writes that do not exist in the original program,
it must not allow a single read to observe multiple values,