Example:
	//go:cgo_ldflag "-lpthread"
	//go:cgo_ldflag "-L/usr/local/sqlite3/lib"

A package compiled with cgo will include directives for both
internal and external linking; the linker will select the appropriate
subset for the chosen linking mode.

Example

As a simple example, consider a package that uses cgo to call C.sin.
The following code will be generated by cgo:

	// compiled by gc

pkg debug/elf, type R_LARCH int #46229
pkg debug/pe, const IMAGE_COMDAT_SELECT_ANY = 2 #51868
pkg debug/pe, const IMAGE_COMDAT_SELECT_ANY ideal-int #51868
pkg debug/pe, const IMAGE_COMDAT_SELECT_ASSOCIATIVE = 5 #51868
pkg debug/pe, const IMAGE_COMDAT_SELECT_ASSOCIATIVE ideal-int #51868
pkg debug/pe, const IMAGE_COMDAT_SELECT_EXACT_MATCH = 4 #51868
pkg debug/pe, const IMAGE_COMDAT_SELECT_EXACT_MATCH ideal-int #51868

						sp >>>= 0;
						Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
					},

					// func valueCall(v ref, m string, args []ref) (ref, bool)
					"syscall/js.valueCall": (sp) => {
						sp >>>= 0;
						try {
							const v = loadValue(sp + 8);
							const m = Reflect.get(v, loadString(sp + 16));
							const args = loadSliceOfValues(sp + 32);
							const result = Reflect.apply(m, v, args);

					f.Preamble += fmt.Sprintf("#line %d %q\n", sourceLine(cg), abspath)
					f.Preamble += commentText(cg) + "\n"
					f.Preamble += "#line 1 \"cgo-generated-wrapper\"\n"
				}
			}

		case *ast.FuncDecl:
			// Also, reject attempts to declare methods on C.T or *C.T.
			// (The generated code would otherwise accept this
			// invalid input; see issue #57926.)
			if decl.Recv != nil && len(decl.Recv.List) > 0 {
				recvType := decl.Recv.List[0].Type

pkg syscall (openbsd-386), const SYS_KILL = 37
pkg syscall (openbsd-386), const SYS_LSTAT = 293
pkg syscall (openbsd-386), const SYS_NANOSLEEP = 240
pkg syscall (openbsd-386), const SYS_SELECT = 93
pkg syscall (openbsd-386), const SYS_SETITIMER = 83
pkg syscall (openbsd-386), const SYS_SETTIMEOFDAY = 122
pkg syscall (openbsd-386), const SYS_STAT = 291
pkg syscall (openbsd-386), const SYS_STATFS = 307

pkg net/netip, type Prefix struct
pkg reflect, const Pointer = 22
pkg reflect, const Pointer Kind
pkg reflect, func PointerTo(Type) Type
pkg reflect, method (*MapIter) Reset(Value)
pkg reflect, method (Value) CanComplex() bool
pkg reflect, method (Value) CanFloat() bool
pkg reflect, method (Value) CanInt() bool
pkg reflect, method (Value) CanUint() bool
pkg reflect, method (Value) FieldByIndexErr([]int) (Value, error)

// license that can be found in the LICENSE file.

package tar

import (
	"bytes"
	"compress/bzip2"
	"crypto/md5"
	"errors"
	"fmt"
	"io"
	"math"
	"os"
	"path"
	"reflect"
	"strconv"
	"strings"
	"testing"
	"time"
)

func TestReader(t *testing.T) {
	vectors := []struct {
		file    string    // Test input file
		headers []*Header // Expected output headers

// This package aims to cover most variations of the format,
// including those produced by GNU and BSD tar tools.
package tar

import (
	"errors"
	"fmt"
	"internal/godebug"
	"io/fs"
	"math"
	"path"
	"reflect"
	"strconv"
	"strings"
	"time"
)

// BUG: Use of the Uid and Gid fields in Header could overflow on 32-bit
// architectures. If a large value is encountered when decoding, the result

	delay := time.Second / 4
	for attempt := 0; attempt < 5; attempt++ {
		conn, err := net.DialTimeout("tcp", "localhost:3222", 5*time.Second)
		if err == nil {
			conn.Close()
			return closer, nil
		}
		select {
		case <-time.After(delay):
			delay *= 2
		case err := <-errChan:
			return nil, err
		}
	}
	closer()
	return nil, errors.New("failed to set up idevicedebugserverproxy")
}

pkg net/http/fcgi, func ProcessEnv(*http.Request) map[string]string
pkg net/http/httptest, method (*Server) Certificate() *x509.Certificate
pkg net/http/httptest, method (*Server) Client() *http.Client
pkg reflect, func MakeMapWithSize(Type, int) Value
pkg runtime/pprof, func Do(context.Context, LabelSet, func(context.Context))
pkg runtime/pprof, func ForLabels(context.Context, func(string, string) bool)