// as an error by any function.
var SkipAll = errors.New("skip everything and stop the walk")

// WalkDirFunc is the type of the function called by [WalkDir] to visit
// each file or directory.
//
// The path argument contains the argument to [WalkDir] as a prefix.
// That is, if WalkDir is called with root argument "dir" and finds a file
// named "a" in that directory, the walk function will be called with
// argument "dir/a".
//

const tmpstringbufsize = 32

func Walk(fn *ir.Func) {
	ir.CurFunc = fn
	errorsBefore := base.Errors()
	order(fn)
	if base.Errors() > errorsBefore {
		return
	}

	if base.Flag.W != 0 {
		s := fmt.Sprintf("\nbefore walk %v", ir.CurFunc.Sym())
		ir.DumpList(s, ir.CurFunc.Body)
	}

	walkStmtList(ir.CurFunc.Body)
	if base.Flag.W != 0 {
		s := fmt.Sprintf("after walk %v", ir.CurFunc.Sym())

		if n.Elt != nil {
			Walk(v, n.Elt)
		}

	case *FuncLit:
		Walk(v, n.Type)
		Walk(v, n.Body)

	case *CompositeLit:
		if n.Type != nil {
			Walk(v, n.Type)
		}
		walkList(v, n.Elts)

	case *ParenExpr:
		Walk(v, n.X)

	case *SelectorExpr:
		Walk(v, n.X)
		Walk(v, n.Sel)

	case *IndexExpr:
		Walk(v, n.X)
		Walk(v, n.Index)

	case *IndexListExpr:
		Walk(v, n.X)

		if s.walkMu != nil {
			s.walkMu.Unlock()
		}
		if err != nil {
			// Folder could have gone away in-between
			if err != errVolumeNotFound && err != errFileNotFound {
				internalLogOnceIf(ctx, err, "metacache-walk-scan-dir")
			}
			if opts.ReportNotFound && err == errFileNotFound && current == opts.BaseDir {
				err = errFileNotFound
			} else {
				err = nil
			}
			diskHealthCheckOK(ctx, err)
			return err

     */
    Stream<FileSystemLocationSnapshot> roots();

    /**
     * Walks the whole hierarchy represented by this snapshot.
     *
     * The walk is depth first.
     */
    SnapshotVisitResult accept(FileSystemSnapshotHierarchyVisitor visitor);

    /**
     * Walks the whole hierarchy represented by this snapshot.
     *
     * The walk is depth first.
     */

	// pointers, usually for alignment."
	var originals []ir.Node
	var walk func(n ir.Node)
	walk = func(n ir.Node) {
		switch n.Op() {
		case ir.OADD:
			n := n.(*ir.BinaryExpr)
			walk(n.X)
			walk(n.Y)
		case ir.OSUB, ir.OANDNOT:
			n := n.(*ir.BinaryExpr)
			walk(n.X)
		case ir.OCONVNOP:
			n := n.(*ir.ConvExpr)
			if n.X.Type().IsUnsafePtr() {

		}
	}
	return nil
}

// walk recursively descends path, calling walkFn.
func walk(path string, info fs.FileInfo, walkFn WalkFunc) error {
	if !info.IsDir() {
		return walkFn(path, info, nil)
	}

	names, err := readDirNames(path)
	err1 := walkFn(path, info, err)
	// If err != nil, walk can't walk into this directory.
	// err1 != nil means walkFn want walk to skip this directory or stop walking.

	}
	return n
}

// walkDot walks an ODOT or ODOTPTR node.
func walkDot(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
	usefield(n)
	n.X = walkExpr(n.X, init)
	return n
}

// walkDotType walks an ODOTTYPE or ODOTTYPE2 node.
func walkDotType(n *ir.TypeAssertExpr, init *ir.Nodes) ir.Node {
	n.X = walkExpr(n.X, init)

	extraCalls map[*ir.Func][]nowritebarrierrecCall

	// curfn is the current function during AST walks.
	curfn *ir.Func
}

type nowritebarrierrecCall struct {
	target *ir.Func // caller or callee
	lineno src.XPos // line of call
}

// newNowritebarrierrecChecker creates a nowritebarrierrecChecker. It
// must be called before walk.
func newNowritebarrierrecChecker() *nowritebarrierrecChecker {
	c := &nowritebarrierrecChecker{

	// to avoid confusion about what gets returned
	// in the presence of type assertions.
}

func walkStmtList(s []ir.Node) {
	for i := range s {
		s[i] = walkStmt(s[i])
	}
}

// walkFor walks an OFOR node.
func walkFor(n *ir.ForStmt) ir.Node {
	if n.Cond != nil {
		init := ir.TakeInit(n.Cond)
		walkStmtList(init)
		n.Cond = walkExpr(n.Cond, &init)
		n.Cond = ir.InitExpr(init, n.Cond)
	}