package types

import (
	"go/ast"
	"go/token"
	. "internal/types/errors"
)

// labels checks correct label use in body.
func (check *Checker) labels(body *ast.BlockStmt) {
	// set of all labels in this body
	all := NewScope(nil, body.Pos(), body.End(), "label")

	fwdJumps := check.blockBranches(all, nil, nil, body.List)

	// If there are any forward jumps left, no label was found for

}

// stripOutputComment finds and removes the "Output:" or "Unordered output:"
// comment from body and comments, and adjusts the body block's end position.
func stripOutputComment(body *ast.BlockStmt, comments []*ast.CommentGroup) (*ast.BlockStmt, []*ast.CommentGroup) {
	// Do nothing if there is no "Output:" or "Unordered output:" comment.
	i, last := lastComment(body, comments)
	if last == nil || !outputPrefix.MatchString(last.Text()) {

type BlockKind uint8

const (
	KindInvalid BlockKind = iota // Stmt=nil

	KindUnreachable     // unreachable block after {Branch,Return}Stmt / no-return call ExprStmt
	KindBody            // function body BlockStmt
	KindForBody         // body of ForStmt
	KindForDone         // block after ForStmt
	KindForLoop         // head of ForStmt
	KindForPost         // post condition of ForStmt
	KindIfDone          // block after IfStmt

// z-assignment statement, because it spans three of its children (:=,
// x, +).  So too is the 1-char interval D, because it contains only
// interior whitespace of the assignment.  E is considered interior
// whitespace of the BlockStmt containing the assignment.
//
// The resulting path is never empty; it always contains at least the
// 'root' *ast.File.  Ideally PathEnclosingInterval would reject

		// we inserted above.
		pos := f.fset.File(n.Body.End()).Pos(elseOffset + 4)
		switch stmt := n.Else.(type) {
		case *ast.IfStmt:
			block := &ast.BlockStmt{
				Lbrace: pos,
				List:   []ast.Stmt{stmt},
				Rbrace: stmt.End(),
			}
			n.Else = block
		case *ast.BlockStmt:
			stmt.Lbrace = pos
		default:
			panic("unexpected node type in if")
		}
		ast.Walk(f, n.Else)
		return nil
	case *ast.SelectStmt:

var fixes []fix

func register(f fix) {
	fixes = append(fixes, f)
}

// walk traverses the AST x, calling visit(y) for each node y in the tree but
// also with a pointer to each ast.Expr, ast.Stmt, and *ast.BlockStmt,
// in a bottom-up traversal.
func walk(x any, visit func(any)) {
	walkBeforeAfter(x, nop, visit)
}

func nop(any) {}

// walkBeforeAfter is like walk but calls before(x) before traversing

//   - bad labeled breaks and continues
//   - invalid, unused, duplicate, and missing labels
//   - gotos jumping over variable declarations and into blocks
func checkBranches(body *BlockStmt, errh ErrorHandler) {
	if body == nil {
		return
	}

	// scope of all labels in this body
	ls := &labelScope{errh: errh}
	fwdGotos := ls.blockBranches(nil, targets{}, nil, body.Pos(), body.List)

	if p.trace {
		defer un(trace(p, "BlockStmt"))
	}

	lbrace := p.expect(token.LBRACE)
	p.openScope()
	list := p.parseStmtList()
	p.closeScope()
	rbrace := p.expect(token.RBRACE)

	return &ast.BlockStmt{lbrace, list, rbrace}
}

// ----------------------------------------------------------------------------
// Expressions

func (p *parser) parseFuncTypeOrLit() ast.Expr {
	if p.trace {

		addVar := func(expr ast.Expr) {
			if id, _ := expr.(*ast.Ident); id != nil {
				if obj := pass.TypesInfo.ObjectOf(id); obj != nil {
					vars = append(vars, obj)
				}
			}
		}
		var body *ast.BlockStmt
		switch n := n.(type) {
		case *ast.File:
			// Only traverse the file if its goversion is strictly before go1.22.
			goversion := versions.FileVersion(pass.TypesInfo, n)

	case *ast.BadExpr:
		return 1 << nBadExpr
	case *ast.BadStmt:
		return 1 << nBadStmt
	case *ast.BasicLit:
		return 1 << nBasicLit
	case *ast.BinaryExpr:
		return 1 << nBinaryExpr
	case *ast.BlockStmt:
		return 1 << nBlockStmt
	case *ast.BranchStmt:
		return 1 << nBranchStmt
	case *ast.CallExpr:
		return 1 << nCallExpr
	case *ast.CaseClause:
		return 1 << nCaseClause
	case *ast.ChanType: