f(func() {
		defer print("A")
	})

because the deferred code will run at the end of the iteration, not
the end of the containing function. To fix that, the runtime provides
a special hook that lets us obtain a defer "token" representing the
outer function and then use it in a later defer to attach the deferred
code to that outer function.

Normally,

	defer print("A")

compiles to

The extra functions here are stubs to satisfy the references in the C
code generated for gcc. The build process links this stub, along with
_cgo_export.c and *.cgo2.c, into a dynamic executable and then lets
cgo examine the executable. Cgo records the list of shared library
references and resolved names and writes them into a new file
_cgo_import.go, which looks like:

	//go:cgo_dynamic_linker "/lib64/ld-linux-x86-64.so.2"

	os.Setenv("GOCACHE", pathf("%s/pkg/obj/go-build", goroot))

	// Disable GOEXPERIMENT when building toolchain1 and
	// go_bootstrap. We don't need any experiments for the
	// bootstrap toolchain, and this lets us avoid duplicating the
	// GOEXPERIMENT-related build logic from cmd/go here. If the
	// bootstrap toolchain is < Go 1.17, it will ignore this
	// anyway since GOEXPERIMENT is baked in; otherwise it will

// are of type ProtocolError.
type ProtocolError struct {
	ErrorString string
}

func (pe *ProtocolError) Error() string { return pe.ErrorString }

// Is lets http.ErrNotSupported match errors.ErrUnsupported.
func (pe *ProtocolError) Is(err error) bool {
	return pe == ErrNotSupported && err == errors.ErrUnsupported
}

var (

		// this is created by code in this file.
		if t.Name == "unsafe.Pointer" {
			return ast.NewIdent("_cgo_unsafe.Pointer")
		}
	case *ast.ArrayType:
		t1 := p.rewriteUnsafe(t.Elt)
		if t1 != t.Elt {
			r := *t
			r.Elt = t1
			return &r
		}
	case *ast.StructType:
		changed := false
		fields := *t.Fields
		fields.List = nil
		for _, f := range t.Fields.List {

			throw("work.nwait was > work.nproc")
		}

		systemstack(func() {
			// Mark our goroutine preemptible so its stack
			// can be scanned. This lets two mark workers
			// scan each other (otherwise, they would
			// deadlock). We must not modify anything on
			// the G stack. However, stack shrinking is
			// disabled for mark workers, so it is safe to

	// The directory in which to create profile files and the like. When run from
	// "go test", the binary always runs in the source directory for the package;
	// this flag lets "go test" tell the binary to write the files in the directory where
	// the "go test" command is run.
	outputDir = flag.String("test.outputdir", "", "write profiles to `dir`")

	r.didClose = true
	return r.ReadCloser.Close()
}

// setupRewindBody returns a new request with a custom body wrapper
// that can report whether the body needs rewinding.
// This lets rewindBody avoid an error result when the request
// does not have GetBody but the body hasn't been read at all yet.
func setupRewindBody(req *Request) *Request {
	if req.Body == nil || req.Body == NoBody {
		return req

	// a cloning allocation. For example, if the driver returns a *string and
	// the user is scanning into a *RawBytes, we need to copy the string.
	// The raw buffer here lets us reuse the memory for that copy across Scan calls.
	raw []byte
}

// lasterrOrErrLocked returns either lasterr or the provided err.
// rs.closemu must be read-locked.

// Hijacker, but HTTP/2 connections intentionally do not.
// ResponseWriter wrappers may also not support Hijacker. Handlers
// should always test for this ability at runtime.
type Hijacker interface {
	// Hijack lets the caller take over the connection.
	// After a call to Hijack the HTTP server library
	// will not do anything else with the connection.
	//
	// It becomes the caller's responsibility to manage