In essence, the _cgo_import.o file includes the extra linking
directives that cmd/link is not sophisticated enough to derive from _all.o
on its own. Similarly, the _all.o uses dynamic references to real
system object code because cmd/link is not sophisticated enough to process
the real code.

The main benefits of this system are that cmd/link remains relatively simple

	}
	swigDir := strings.TrimSpace(string(output))

	_, err = os.Stat(filepath.Join(swigDir, "go"))
	if err != nil {
		t.Skip("swig is missing Go support")
	}

	// Check that swig has a new enough version.
	// See https://golang.org/issue/22858.
	out, err := exec.Command(swig, "-version").CombinedOutput()
	if err != nil {
		t.Skipf("failed to get swig version:%s\n%s", err, string(out))
	}

import (
	"internal/reflectlite"
	"unsafe"
)

// Arena represents a collection of Go values allocated and freed together.
// Arenas are useful for improving efficiency as they may be freed back to
// the runtime manually, though any memory obtained from freed arenas must
// not be accessed once that happens. An Arena is automatically freed once
// it is no longer referenced, so it must be kept alive (see runtime.KeepAlive)

// a list of exported functions, and the actual AST, to be rewritten and
// printed.
func (f *File) ParseGo(abspath string, src []byte) {
	// Two different parses: once with comments, once without.
	// The printer is not good enough at printing comments in the
	// right place when we start editing the AST behind its back,
	// so we use ast1 to look for the doc comments on import "C"
	// and on exported functions, and we use ast2 for translating

	{
		tw := &teststringwriter{}
		b := NewWriterSize(tw, BufSize)
		b.WriteString("1234")
		tw.check(t, "", "")
		b.WriteString("56789012")   // longer than BufSize
		tw.check(t, "12345678", "") // but not enough (after filling the partially-filled buffer)
		b.Flush()
		tw.check(t, "123456789012", "")
	}
	{
		tw := &teststringwriter{}
		b := NewWriterSize(tw, BufSize)

<p>
There is also a set of predeclared numeric types with implementation-specific sizes:
</p>

<pre class="grammar">
uint     either 32 or 64 bits
int      same size as uint
uintptr  an unsigned integer large enough to store the uninterpreted bits of a pointer value
</pre>

<p>
To avoid portability issues all numeric types are <a href="#Type_definitions">defined
types</a> and thus distinct except

		f.err = ErrFieldTooLong
	}
	copy(b, s)
	if len(s) < len(b) {
		b[len(s)] = 0
	}

	// Some buggy readers treat regular files with a trailing slash
	// in the V7 path field as a directory even though the full path
	// recorded elsewhere (e.g., via PAX record) contains no trailing slash.
	if len(s) > len(b) && b[len(b)-1] == '/' {
		n := len(strings.TrimRight(s[:len(b)-1], "/"))

	//
	// Instead use the append-make pattern with a nil slice to ensure that
	// we allocate buffers rounded up to the closest size class.
	c := len(b) + n // ensure enough space for n elements
	if c < 2*cap(b) {
		// The growth rate has historically always been 2x. In the future,
		// we could rely purely on append to determine the growth rate.
		c = 2 * cap(b)
	}

}

// alignSparseEntries mutates src and returns dst where each fragment's
// starting offset is aligned up to the nearest block edge, and each
// ending offset is aligned down to the nearest block edge.
//
// Even though the Go tar Reader and the BSD tar utility can handle entries
// with arbitrary offsets and lengths, the GNU tar utility can only handle
// offsets and lengths that are multiples of blockSize.

	// Extract the types from the DWARF section of an object
	// from a well-formed C program. Gcc only generates DWARF info
	// for symbols in the object file, so it is not enough to print the
	// preamble and hope the symbols we care about will be there.
	// Instead, emit
	//	__typeof__(names[i]) *__cgo__i;
	// for each entry in names and then dereference the type we
	// learn for __cgo__i.