if ctxt.Debugvlog > 0 {
		// dump symbol info on crash
		defer func() { ctxt.loader.Dump() }()
	}
	if ctxt.Debugvlog > 1 {
		// dump symbol info on error
		AtExit(func() {
			if nerrors > 0 {
				ctxt.loader.Dump()
			}
		})
	}

	switch *flagHeadType {
	case "":
	case "windowsgui":
		ctxt.HeadType = objabi.Hwindows
		windowsgui = true
	default:

}

// An expression is represented by a tree consisting of one
// or more of the following concrete expression nodes.
type (
	// A BadExpr node is a placeholder for an expression containing
	// syntax errors for which a correct expression node cannot be
	// created.
	//
	BadExpr struct {
		From, To token.Pos // position range of bad expression
	}

	// An Ident node represents an identifier.
	Ident struct {

	case *ast.UnaryExpr:
		children = append(children, tok(n.OpPos, len(n.Op.String())))

	case *ast.ValueSpec:
		// TODO(adonovan): ValueSpec.{Doc,Comment}?

	case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt:
		// nop
	}

	// TODO(adonovan): opt: merge the logic of ast.Inspect() into
	// the switch above so we can make interleaved callbacks for

	// We could use a temporary directory outside $GOROOT instead,
	// but it is easier to debug on failure if the files are in a known location.
	workspace := pathf("%s/pkg/bootstrap", goroot)
	xremoveall(workspace)
	xatexit(func() { xremoveall(workspace) })
	base := pathf("%s/src/bootstrap", workspace)
	xmkdirall(base)

	// Copy source code into $GOROOT/pkg/bootstrap and rewrite import paths.

	"strconv"
	"sync"
)

var buildInitStarted = false

func BuildInit() {
	if buildInitStarted {
		base.Fatalf("go: internal error: work.BuildInit called more than once")
	}
	buildInitStarted = true
	base.AtExit(closeBuilders)

	modload.Init()
	instrumentInit()
	buildModeInit()
	if err := fsys.Init(base.Cwd()); err != nil {
		base.Fatal(err)
	}

	// Make sure -pkgdir is absolute, because we run commands

	if cfg.DebugTrace == "" {
		return pctx
	}

	ctx, close, err := trace.Start(pctx, cfg.DebugTrace)
	if err != nil {
		base.Fatalf("failed to start trace: %v", err)
	}
	base.AtExit(func() {
		if err := close(); err != nil {
			base.Fatalf("failed to stop trace: %v", err)
		}
	})

	return ctx
}

// handleChdirFlag handles the -C flag before doing anything else.

		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Tag", nil, n.Tag)
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.FieldList:
		a.applyList(n, "List")

	// Expressions
	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
		// nothing to do

	case *ast.Ellipsis:
		a.apply(n, "Elt", nil, n.Elt)

	case *ast.FuncLit:
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Body", nil, n.Body)

				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
			} else {
				check.trace(e0.Pos(), "=> %s (under = %s) // %s", T, under, goTypeName(T))
			}
		}()
	}

	switch e := e0.(type) {
	case *syntax.BadExpr:
		// ignore - error reported before

	case *syntax.Name:
		var x operand
		check.ident(&x, e, def, true)

		switch x.mode {
		case typexpr:
			typ := x.typ
			setDefType(def, typ)

	// already held it's assumed that the first caller exits the program
	// so other calls can hang forever without an issue.
	lock(&raceFiniLock)

	// __tsan_fini will run C atexit functions and C++ destructors,
	// which can theoretically call back into Go.
	// Tell the scheduler we entering external code.
	entersyscall()

	// We're entering external code that may call ExitProcess on

				check.trace(e0.Pos(), "=> %s // %s", T, goTypeName(T))
			} else {
				check.trace(e0.Pos(), "=> %s (under = %s) // %s", T, under, goTypeName(T))
			}
		}()
	}

	switch e := e0.(type) {
	case *ast.BadExpr:
		// ignore - error reported before

	case *ast.Ident:
		var x operand
		check.ident(&x, e, def, true)

		switch x.mode {
		case typexpr:
			typ := x.typ
			setDefType(def, typ)