enormous amount of work.

Cgo takes a different approach. It determines the meaning of C
identifiers not by parsing C code but by feeding carefully constructed
programs into the system C compiler and interpreting the generated
error messages, debug information, and object files. In practice,
parsing these is significantly less work and more robust than parsing
C source.

Cgo first invokes gcc -E -dM on the preamble, in order to find out

line := Line{origin, Point3D{y: -4, z: 12.3}}  // zero value for line.q.x
</pre>

<p>
For array and slice literals the following rules apply:
</p>
<ul>
	<li>Each element has an associated integer index marking
	    its position in the array.
	</li>
	<li>An element with a key uses the key as its index. The
	    key must be a non-negative constant
	    <a href="#Representability">representable</a> by

	// This package transparently handles these types.
	TypeXHeader = 'x'

	// Type 'g' is used by the PAX format to store key-value records that
	// are relevant to all subsequent files.
	// This package only supports parsing and composing such headers,
	// but does not currently support persisting the global state across files.
	TypeXGlobalHeader = 'g'

	// Type 'S' indicates a sparse file in the GNU format.
	TypeGNUSparse = 'S'

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

	}
	h.SetModTime(ts)

	testValidHeader(&h, t)
}

func TestHeaderTooShort(t *testing.T) {
	h := FileHeader{
		Name:   "foo.txt",
		Method: Deflate,
		Extra:  []byte{zip64ExtraID}, // missing size and second half of tag, but Extra is best-effort parsing
	}
	testValidHeader(&h, t)
}

<p>
Just as each ordinary function parameter has a parameter type, each type parameter
has a corresponding (meta-)type which is called its
<a href="#Type_constraints"><i>type constraint</i></a>.
</p>

<p>
A parsing ambiguity arises when the type parameter list for a generic type
declares a single type parameter <code>P</code> with a constraint <code>C</code>
such that the text <code>P C</code> forms a valid expression:
</p>

// If they are found, then this function reads the sparse map and returns it.
// This assumes that 0.0 headers have already been converted to 0.1 headers
// by the PAX header parsing logic.
func (tr *Reader) readGNUSparsePAXHeaders(hdr *Header) (sparseDatas, error) {
	// Identify the version of GNU headers.
	var is1x0 bool

	// Parse package files.
	var files []*ast.File
	for _, file := range filenames {
		f, err := w.parseFile(dir, file)
		if err != nil {
			log.Fatalf("error parsing package %s: %s", name, err)
		}
		files = append(files, f)
	}

	// Type-check package files.
	var sizes types.Sizes
	if w.context != nil {
		sizes = types.SizesFor(w.context.Compiler, w.context.GOARCH)