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")
	}

decide which.

The obvious thing for cgo to do is to process the preamble, expanding
#includes and processing the corresponding C code. That would require
a full C parser and type checker that was also aware of any extensions
known to the system compiler (for example, all the GNU C extensions) as
well as the system-specific header locations and system-specific

</pre>

<p>
the variable <code>a</code> will be initialized after <code>b</code> but
whether <code>x</code> is initialized before <code>b</code>, between
<code>b</code> and <code>a</code>, or after <code>a</code>, and
thus also the moment at which <code>sideEffect()</code> is called (before
or after <code>x</code> is initialized) is not specified.
</p>

<p>

field, [`Policies`](/pkg/crypto/x509/#Certificate.Policies), which supports
certificate policy OIDs with components larger than 31 bits. By default this
field is only used during parsing, when it is populated with policy OIDs, but
not used during marshaling. It can be used to marshal these larger OIDs, instead
of the existing PolicyIdentifiers field, by using the
[`x509usepolicies` setting.](/pkg/crypto/x509/#CreateCertificate).

	n := len(b) * count

	if len(b) == 0 {
		return []byte{}
	}

	// Past a certain chunk size it is counterproductive to use
	// larger chunks as the source of the write, as when the source
	// is too large we are basically just thrashing the CPU D-cache.
	// So if the result length is larger than an empirically-found
	// limit (8KB), we stop growing the source string once the limit

	ADD $-8589869055, R5            // 3fe0fffe63ff00017bff83e463ff00017cbf2a14 or 0602000138a50001

	//TODO: this compiles to add r5,r6,r0. It should be addi r5,r6,0.
	//      this is OK since r0 == $0, but the latter is preferred.
	ADD $0, R6, R5             	// 7ca60214

        //TODO: the assembler rewrites these into ADDIS $19, R5, Rx and ADD $-10617, Rx, Rx, but the test only sees the first ADDIS

</pre>

<p>
the variable <code>a</code> will be initialized after <code>b</code> but
whether <code>x</code> is initialized before <code>b</code>, between
<code>b</code> and <code>a</code>, or after <code>a</code>, and
thus also the moment at which <code>sideEffect()</code> is called (before
or after <code>x</code> is initialized) is not specified.
</p>

<p>

</p>

<p>
Reads of memory locations larger than a single machine word
are encouraged but not required to meet the same semantics
as word-sized memory locations,
observing a single allowed write <i>w</i>.
For performance reasons,
implementations may instead treat larger operations
as a set of individual machine-word-sized operations
in an unspecified order.

		case TypeGNULongName, TypeGNULongLink:
			format.mayOnlyBe(FormatGNU)
			realname, err := readSpecialFile(tr)
			if err != nil {
				return nil, err
			}

			var p parser
			switch hdr.Typeflag {
			case TypeGNULongName:
				gnuLongName = p.parseString(realname)
			case TypeGNULongLink:
				gnuLongLink = p.parseString(realname)
			}

func (w *Walker) parseFile(dir, file string) (*ast.File, error) {
	filename := filepath.Join(dir, file)
	if f := parsedFileCache[filename]; f != nil {
		return f, nil
	}

	f, err := parser.ParseFile(fset, filename, nil, parser.ParseComments)
	if err != nil {
		return nil, err
	}
	parsedFileCache[filename] = f

	return f, nil
}

// Disable before debugging non-obvious errors from the type-checker.