Go 1.26 で追加される modernize tools の一覧と詳細について

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/versions"
)

var AnyAnalyzer = &analysis.Analyzer{
	Name:     "any",
	Doc:      analyzerutil.MustExtractDoc(doc, "any"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      runAny,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#any",
}

// The any pass replaces interface{} with go1.18's 'any'.
func runAny(pass *analysis.Pass) (any, error) {
	for curFile := range filesUsingGoVersion(pass, versions.Go1_18) {
		for curIface := range curFile.Preorder((*ast.InterfaceType)(nil)) {
			iface := curIface.Node().(*ast.InterfaceType)

			if iface.Methods.NumFields() == 0 {
				// Check that 'any' is not shadowed.
				if lookup(pass.TypesInfo, curIface, "any") == builtinAny {
					pass.Report(analysis.Diagnostic{
						Pos:     iface.Pos(),
						End:     iface.End(),
						Message: "interface{} can be replaced by any",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Replace interface{} by any",
							TextEdits: []analysis.TextEdit{
								{
									Pos:     iface.Pos(),
									End:     iface.End(),
									NewText: []byte("any"),
								},
							},
						}},
					})
				}
			}
		}
	}
	return nil, nil
}

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var FmtAppendfAnalyzer = &analysis.Analyzer{
	Name: "fmtappendf",
	Doc:  analyzerutil.MustExtractDoc(doc, "fmtappendf"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: fmtappendf,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#fmtappendf",
}

// The fmtappend function replaces []byte(fmt.Sprintf(...)) by
// fmt.Appendf(nil, ...), and similarly for Sprint, Sprintln.
func fmtappendf(pass *analysis.Pass) (any, error) {
	index := pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	for _, fn := range []types.Object{
		index.Object("fmt", "Sprintf"),
		index.Object("fmt", "Sprintln"),
		index.Object("fmt", "Sprint"),
	} {
		for curCall := range index.Calls(fn) {
			call := curCall.Node().(*ast.CallExpr)
			if ek, idx := curCall.ParentEdge(); ek == edge.CallExpr_Args && idx == 0 {
				// Is parent a T(fmt.SprintX(...)) conversion?
				conv := curCall.Parent().Node().(*ast.CallExpr)
				tv := pass.TypesInfo.Types[conv.Fun]
				if tv.IsType() && types.Identical(tv.Type, byteSliceType) &&
					analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(curCall), versions.Go1_19) {
					// Have: []byte(fmt.SprintX(...))

					// Find "Sprint" identifier.
					var id *ast.Ident
					switch e := ast.Unparen(call.Fun).(type) {
					case *ast.SelectorExpr:
						id = e.Sel // "fmt.Sprint"
					case *ast.Ident:
						id = e // "Sprint" after `import . "fmt"`
					}

					old, new := fn.Name(), strings.Replace(fn.Name(), "Sprint", "Append", 1)
					edits := []analysis.TextEdit{
						{
							// delete "[]byte("
							Pos: conv.Pos(),
							End: conv.Lparen + 1,
						},
						{
							// remove ")"
							Pos: conv.Rparen,
							End: conv.Rparen + 1,
						},
						{
							Pos: id.Pos(),
							End: id.End(),
							NewText: []byte(new),
						},
						{
							Pos: call.Lparen + 1,
							NewText: []byte("nil, "),
						},
					}
					if len(conv.Args) == 1 {
						arg := conv.Args[0]
						// Determine if we have T(fmt.SprintX(...)). If so, delete the non-args
						// that come before the right parenthesis. Leaving an
						// extra comma here produces invalid code. (See
						// golang/go#74709)
						if arg.End() < conv.Rparen {
							edits = append(edits, analysis.TextEdit{
								Pos: arg.End(),
								End: conv.Rparen,
							})
						}
					}
					pass.Report(analysis.Diagnostic{
						Pos:     conv.Pos(),
						End:     conv.End(),
						Message: fmt.Sprintf("Replace []byte(fmt.%s...) with fmt.%s", old, new),
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: fmt.Sprintf("Replace []byte(fmt.%s...) with fmt.%s", old, new),
							TextEdits: edits,
						}},
					})
				}
			}
		}
	}
	return nil, nil
}

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/versions"
)

var ForVarAnalyzer = &analysis.Analyzer{
	Name:     "forvar",
	Doc:      analyzerutil.MustExtractDoc(doc, "forvar"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      forvar,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#forvar",
}

// forvar offers to fix unnecessary copying of a for variable
func forvar(pass *analysis.Pass) (any, error) {
	for curFile := range filesUsingGoVersion(pass, versions.Go1_22) {
		for curLoop := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			loop := curLoop.Node().(*ast.RangeStmt)
			if loop.Tok != token.DEFINE {
				continue
			}
			isLoopVarRedecl := func(stmt ast.Stmt) bool {
				if assign, ok := stmt.(*ast.AssignStmt); ok &&
					assign.Tok == token.DEFINE &&
					len(assign.Lhs) == len(assign.Rhs) {

					for i, lhs := range assign.Lhs {
						if !(astutil.EqualSyntax(lhs, assign.Rhs[i]) &&
							(astutil.EqualSyntax(lhs, loop.Key) ||
								astutil.EqualSyntax(lhs, loop.Value))) {
							return false
						}
					}
					return true
				}
				return false
			}
			// Have: for k, v := range x { stmts }
			//
			// Delete the prefix of stmts that are
			// of the form k := k; v := v; k, v := k, v; v, k := v, k.
			for _, stmt := range loop.Body.List {
				if isLoopVarRedecl(stmt) {
					// { x := x; ... }
					// ------
				} else if ifstmt, ok := stmt.(*ast.IfStmt); ok &&
					ifstmt.Init != nil &&
					len(loop.Body.List) == 1 && // must be sole statement in loop body
					isLoopVarRedecl(ifstmt.Init) {
					// if x := x; cond {
					// ------
					stmt = ifstmt.Init
				} else {
					break // stop at first other statement
				}

				curStmt, _ := curLoop.FindNode(stmt)
				edits := refactor.DeleteStmt(pass.Fset.File(stmt.Pos()), curStmt)
				if len(edits) > 0 {
					pass.Report(analysis.Diagnostic{
						Pos:     stmt.Pos(),
						End:     stmt.End(),
						Message: "copying variable is unneeded",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Remove unneeded redeclaration",
							TextEdits: edits,
						}},
					})
				}
			}
		}
	}
	return nil, nil
}

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

// This file defines modernizers that use the "maps" package.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

var MapsLoopAnalyzer = &analysis.Analyzer{
	Name:     "mapsloop",
	Doc:      analyzerutil.MustExtractDoc(doc, "mapsloop"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      mapsloop,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#mapsloop",
}

// The mapsloop pass offers to simplify a loop of map insertions:
//
// for k, v := range x {
// m[k] = v
// }
//
// by a call to go1.23's maps package.
func mapsloop(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "maps", "bytes", "runtime") {
		return nil, nil
	}

	info := pass.TypesInfo

	// check is called for each statement of this form:
	// for k, v := range x { m[k] = v }
	check := func(file *ast.File, curRange inspector.Cursor, assign *ast.AssignStmt, m, x ast.Expr) {
		// Is x a map or iter.Seq2?
		tx := types.Unalias(info.TypeOf(x))
		var xmap bool
		switch typeparams.CoreType(tx).(type) {
		case *types.Map:
			xmap = true

		case *types.Signature:
			k, v, ok := assignableToIterSeq2(tx)
			if !ok {
				return
			}
			xmap = false
			tx = types.NewMap(k, v)

		default:
			return
		}

		// Choose function.
		var funcName string
		funcName = cond(xmap, "Copy", "Insert")

		// Report diagnostic, and suggest fix.
		rng := curRange.Node()
		prefix, importEdits := refactor.AddImport(info, file, "maps", "maps", funcName, rng.Pos())
		var (
			newText []byte
			start, end token.Pos
		)

		// Replace loop with call statement.
		start, end = rng.Pos(), rng.End()
		newText = fmt.Appendf(nil, "%s%s%s(%s, %s)",
			allComments(file, start, end),
			prefix,
			funcName,
			astutil.Format(pass.Fset, m),
			astutil.Format(pass.Fset, x))

		pass.Report(analysis.Diagnostic{
			Pos:     assign.Lhs[0].Pos(),
			End:     assign.Lhs[0].End(),
			Message: "Replace m[k]=v loop with maps." + funcName,
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Replace m[k]=v loop with maps." + funcName,
				TextEdits: append(importEdits, []analysis.TextEdit{{
					Pos:     start,
					End:     end,
					NewText: newText,
				}}...),
			}},
		})
	}

	// Find all range loops around m[k] = v.
	for curFile := range filesUsingGoVersion(pass, versions.Go1_23) {
		file := curFile.Node().(*ast.File)

		for curRange := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			rng := curRange.Node().(*ast.RangeStmt)

			if rng.Tok == token.DEFINE &&
				rng.Key != nil &&
				rng.Value != nil &&
				isAssignBlock(rng.Body) {
				// Have: for k, v := range x { lhs = rhs }

				assign := rng.Body.List[0].(*ast.AssignStmt)

				if index, ok := assign.Lhs[0].(*ast.IndexExpr); ok &&
					len(assign.Lhs) == 1 &&
					astutil.EqualSyntax(rng.Key, index.Index) &&
					astutil.EqualSyntax(rng.Value, assign.Rhs[0]) {
					if tmap, ok := typeparams.CoreType(info.TypeOf(index.X)).(*types.Map); ok &&
						types.Identical(info.TypeOf(index), info.TypeOf(rng.Value)) &&
						types.Identical(tmap.Key(), info.TypeOf(rng.Key)) {

						// Have: for k, v := range x { m[k] = v }
						check(file, curRange, assign, index.X, rng.X)
					}
				}
			}
		}
	}
	return nil, nil
}

// assignableToIterSeq2 reports whether t is assignable to
// iter.Seq[K, V] and returns K and V if so.
func assignableToIterSeq2(t types.Type) (k, v types.Type, ok bool) {
	if is[*types.Named](t) {
		if !typesinternal.IsTypeNamed(t, "iter", "Seq2") {
			return
		}
		t = t.Underlying()
	}

	if t, ok := t.(*types.Signature); ok {
		if t.Params().Len() == 1 && t.Results().Len() == 0 {
			if yield, ok := t.Params().At(0).Type().(*types.Signature); ok {
				if yield.Params().Len() == 2 &&
					yield.Results().Len() == 1 &&
					types.Identical(yield.Results().At(0).Type(), builtinBool.Type()) {
					return yield.Params().At(0).Type(), yield.Params().At(1).Type(), true
				}
			}
		}
	}
	return
}

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var MinMaxAnalyzer = &analysis.Analyzer{
	Name: "minmax",
	Doc:  analyzerutil.MustExtractDoc(doc, "minmax"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: minmax,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#minmax",
}

// The minmax pass replaces if/else statements with calls to min or max,
// and removes user-defined min/max functions that are equivalent to built-ins.
func minmax(pass *analysis.Pass) (any, error) {
	// Check for user-defined min/max functions that can be removed
	checkUserDefinedMinMax(pass)

	// check is called for all statements of this form:
	// if a < b { lhs = rhs }
	check := func(file *ast.File, curIfStmt inspector.Cursor, compare *ast.BinaryExpr) {
		var (
			ifStmt  = curIfStmt.Node().(*ast.IfStmt)
			tassign = ifStmt.Body.List[0].(*ast.AssignStmt)
			a       = compare.X
			b       = compare.Y
			lhs     = tassign.Lhs[0]
			rhs     = tassign.Rhs[0]
			sign    = isInequality(compare.Op)
		)

		if fblock, ok := ifStmt.Else.(*ast.BlockStmt); ok && isAssignBlock(fblock) {
			fassign := fblock.List[0].(*ast.AssignStmt)

			// Have: if a < b { lhs = rhs } else { lhs2 = rhs2 }
			lhs2 := fassign.Lhs[0]
			rhs2 := fassign.Rhs[0]

			// For pattern 1, check that:
			// - lhs = lhs2
			// - {rhs,rhs2} = {a,b}
			if astutil.EqualSyntax(lhs, lhs2) {
				if astutil.EqualSyntax(rhs, a) && astutil.EqualSyntax(rhs2, b) {
					sign = +sign
				} else if astutil.EqualSyntax(rhs2, a) && astutil.EqualSyntax(rhs, b) {
					sign = -sign
				} else {
					return
				}

				sym := cond(sign < 0, "min", "max")

				if !is[*types.Builtin](lookup(pass.TypesInfo, curIfStmt, sym)) {
					return // min/max function is shadowed
				}

				// pattern 1
				pass.Report(analysis.Diagnostic{
					// Highlight the condition a < b.
					Pos:     compare.Pos(),
					End:     compare.End(),
					Message: fmt.Sprintf("if/else statement can be modernized using %s", sym),
					SuggestedFixes: []analysis.SuggestedFix{{
						Message: fmt.Sprintf("Replace if statement with %s", sym),
						TextEdits: []analysis.TextEdit{{
							// Replace IfStmt with lhs = min(a, b).
							Pos:     ifStmt.Pos(),
							End:     ifStmt.End(),
							NewText: fmt.Appendf(nil, "%s = %s(%s, %s)",
								astutil.Format(pass.Fset, lhs),
								sym,
								astutil.Format(pass.Fset, a),
								astutil.Format(pass.Fset, b),
							),
						}},
					}},
				})
			}
		}
	}

	// Find all "if a < b { lhs = rhs }" statements.
	info := pass.TypesInfo
	for curFile := range filesUsingGoVersion(pass, versions.Go1_21) {
		astFile := curFile.Node().(*ast.File)
		for curIfStmt := range curFile.Preorder((*ast.IfStmt)(nil)) {
			ifStmt := curIfStmt.Node().(*ast.IfStmt)

			if compare, ok := ifStmt.Cond.(*ast.BinaryExpr); ok &&
				ifStmt.Init == nil &&
				isInequality(compare.Op) != 0 &&
				isAssignBlock(ifStmt.Body) {
				// a blank var has no type.
				if tLHS := info.TypeOf(ifStmt.Body.List[0].(*ast.AssignStmt).Lhs[0]); tLHS != nil && !maybeNaN(tLHS) {
					// Have: if a < b { lhs = rhs }
					check(astFile, curIfStmt, compare)
				}
			}
		}
	}
	return nil, nil
}

// isInequality reports non-zero if tok is one of < <= => >:
// +1 for > and -1 for <.
func isInequality(tok token.Token) int {
	switch tok {
	case token.LEQ, token.LSS:
		return -1
	case token.GEQ, token.GTR:
		return +1
	}
	return 0
}

// isAssignBlock reports whether b is a block of the form { lhs = rhs }.
func isAssignBlock(b *ast.BlockStmt) bool {
	if len(b.List) != 1 {
		return false
	}
	return isSimpleAssign(b.List[0])
}

// isSimpleAssign reports whether n has the form "lhs = rhs" or "lhs := rhs".
func isSimpleAssign(n ast.Node) bool {
	assign, ok := n.(*ast.AssignStmt)
	return ok &&
		(assign.Tok == token.ASSIGN || assign.Tok == token.DEFINE) &&
		len(assign.Lhs) == 1 &&
		len(assign.Rhs) == 1
}

// maybeNaN reports whether t is (or may be) a floating-point type.
func maybeNaN(t types.Type) bool {
	t = typeparams.CoreType(t)
	if t == nil {
		return true // fail safe
	}
	if basic, ok := t.(*types.Basic); ok && basic.Info()&types.IsFloat != 0 {
		return true
	}
	return false
}

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/versions"
)

var NewExprAnalyzer = &analysis.Analyzer{
	Name:      "newexpr",
	Doc:       analyzerutil.MustExtractDoc(doc, "newexpr"),
	URL:       "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#newexpr",
	Requires:  []*analysis.Analyzer{inspect.Analyzer},
	Run:       run,
	FactTypes: []analysis.Fact{&newLike{}},
}

func run(pass *analysis.Pass) (any, error) {
	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info    = pass.TypesInfo
	)

	// Detect functions that are new-like, i.e. have the form:
	//
	// func f(x T) *T { return &x }
	//
	// meaning that it is equivalent to new(x), if x has type T.
	for curFuncDecl := range inspect.Root().Preorder((*ast.FuncDecl)(nil)) {
		decl := curFuncDecl.Node().(*ast.FuncDecl)
		fn := info.Defs[decl.Name].(*types.Func)
		if decl.Body != nil && len(decl.Body.List) == 1 {
			if ret, ok := decl.Body.List[0].(*ast.ReturnStmt); ok && len(ret.Results) == 1 {
				if unary, ok := ret.Results[0].(*ast.UnaryExpr); ok && unary.Op == token.AND {
					if id, ok := unary.X.(*ast.Ident); ok {
						if v, ok := info.Uses[id].(*types.Var); ok {
							sig := fn.Signature()
							if sig.Results().Len() == 1 &&
								is[*types.Pointer](sig.Results().At(0).Type()) &&
								sig.Params().Len() == 1 &&
								sig.Params().At(0) == v {

								// Export a fact for each one.
								pass.ExportObjectFact(fn, &newLike{})

								// Check file version.
								file := astutil.EnclosingFile(curFuncDecl)
								if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_26) {
									continue // new(expr) not available in this file
								}

								var edits []analysis.TextEdit

								// If 'new' is not shadowed, replace func body: &x -> new(x).
								curRet, _ := curFuncDecl.FindNode(ret)
								if lookup(info, curRet, "new") == builtinNew {
									edits = []analysis.TextEdit{
										// return &x
										// ---- -
										// return new(x)
										{
											Pos:     unary.OpPos,
											End:     unary.OpPos + token.Pos(len("&")),
											NewText: []byte("new("),
										},
										{
											Pos:     unary.X.End(),
											End:     unary.X.End(),
											NewText: []byte(")"),
										},
									}
								}

								// Add a //go:fix inline annotation, if not already present.
								if !strings.Contains(decl.Doc.Text(), "go:fix inline") {
									edits = append(edits, analysis.TextEdit{
										Pos:     decl.Pos(),
										End:     decl.Pos(),
										NewText: []byte("//go:fix inline\n"),
									})
								}

								if len(edits) > 0 {
									pass.Report(analysis.Diagnostic{
										Pos:     decl.Name.Pos(),
										End:     decl.Name.End(),
										Message: fmt.Sprintf("%s can be an inlinable wrapper around new(expr)", decl.Name),
										SuggestedFixes: []analysis.SuggestedFix{
											{
												Message: "Make %s an inlinable wrapper around new(expr)",
												TextEdits: edits,
											},
										},
									})
								}
							}
						}
					}
				}
			}
		}
	}

	// Report and transform calls, when safe.
	for curCall := range inspect.Root().Preorder((*ast.CallExpr)(nil)) {
		call := curCall.Node().(*ast.CallExpr)
		var fact newLike
		if fn, ok := typeutil.Callee(info, call).(*types.Func); ok &&
			pass.ImportObjectFact(fn, &fact) {

			// Check file version.
			file := astutil.EnclosingFile(curCall)
			if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_26) {
				continue
			}

			// Check new is not shadowed.
			if lookup(info, curCall, "new") != builtinNew {
				continue
			}

			pass.Report(analysis.Diagnostic{
				Pos:     call.Pos(),
				End:     call.End(),
				Message: fmt.Sprintf("call of %s(x) can be simplified to new(x)", fn.Name()),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: fmt.Sprintf("Simplify %s(x) to new(x)", fn.Name()),
					TextEdits: []analysis.TextEdit{{
						Pos:     call.Fun.Pos(),
						End:     call.Fun.End(),
						NewText: []byte("new"),
					}},
				}},
			})
		}
	}

	return nil, nil
}

// A newLike fact records that its associated function is "new-like".
type newLike struct{}

func (*newLike) AFact() {}
func (*newLike) String() string { return "newlike" }

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/types"
	"reflect"
	"strconv"
	"strings"
	"sync"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/versions"
)

var OmitZeroAnalyzer = &analysis.Analyzer{
	Name:     "omitzero",
	Doc:      analyzerutil.MustExtractDoc(doc, "omitzero"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      omitzero,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#omitzero",
}

// The omitzero pass searches for instances of "omitempty" in a json field tag on a
// struct. Since "omitempty" does not have any effect when applied to a struct field,
// it suggests either deleting "omitempty" or replacing it with "omitzero", which
// correctly excludes structs from a json encoding.
func omitzero(pass *analysis.Pass) (any, error) {
	// usesKubebuilder reports whether "+kubebuilder:" appears in
	// any comment in the package, since it has its own
	// interpretation of what omitzero means; see go.dev/issue/76649.
	usesKubebuilder := sync.OnceValue[bool](func() bool {
		for _, file := range pass.Files {
			for _, comment := range file.Comments {
				if strings.Contains(comment.Text(), "+kubebuilder:") {
					return true
				}
			}
		}
		return false
	})

	checkField := func(field *ast.Field) {
		typ := pass.TypesInfo.TypeOf(field.Type)
		_, ok := typ.Underlying().(*types.Struct)
		if !ok {
			return
		}
		tag := field.Tag
		if tag == nil {
			return
		}
		tagconv, _ := strconv.Unquote(tag.Value)
		match := omitemptyRegex.FindStringSubmatchIndex(tagconv)
		if match == nil {
			return
		}
		omitEmpty, err := astutil.RangeInStringLiteral(field.Tag, match[2], match[3])
		if err != nil {
			return
		}
		var remove analysis.Range = omitEmpty

		jsonTag := reflect.StructTag(tagconv).Get("json")
		if jsonTag == ",omitempty" {
			if match[1]-match[0] == len(tagconv) {
				remove = field.Tag
			} else {
				remove, err = astutil.RangeInStringLiteral(field.Tag, match[0], match[1])
				if err != nil {
					return
				}
			}
		}

		if usesKubebuilder() {
			return
		}

		pass.Report(analysis.Diagnostic{
			Pos:     field.Tag.Pos(),
			End:     field.Tag.End(),
			Message: "Omitempty has no effect on nested struct fields",
			SuggestedFixes: []analysis.SuggestedFix{
				{
					Message: "Remove redundant omitempty tag",
					TextEdits: []analysis.TextEdit{
						{
							Pos: remove.Pos(),
							End: remove.End(),
						},
					},
				},
				{
					Message: "Replace omitempty with omitzero (behavior change)",
					TextEdits: []analysis.TextEdit{
						{
							Pos:     omitEmpty.Pos(),
							End:     omitEmpty.End(),
							NewText: []byte(",omitzero"),
						},
					},
				},
			},
		})
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_24) {
		for curStruct := range curFile.Preorder((*ast.StructType)(nil)) {
			for _, curField := range curStruct.Node().(*ast.StructType).Fields.List {
				checkField(curField)
			}
		}
	}

	return nil, nil
}

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/parser"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/versions"
)

var plusBuildAnalyzer = &analysis.Analyzer{
	Name: "plusbuild",
	Doc:  analyzerutil.MustExtractDoc(doc, "plusbuild"),
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#plusbuild",
	Run:  plusbuild,
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.PlusBuildModernizer = plusBuildAnalyzer
}

func plusbuild(pass *analysis.Pass) (any, error) {
	check := func(f *ast.File) {
		if !analyzerutil.FileUsesGoVersion(pass, f, versions.Go1_18) {
			return
		}

		for _, g := range f.Comments {
			sawGoBuild := false
			for _, c := range g.List {
				if sawGoBuild && strings.HasPrefix(c.Text, "// +build ") {
					pass.Report(analysis.Diagnostic{
						Pos:     c.Pos(),
						End:     c.End(),
						Message: "+build line is no longer needed",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Remove obsolete +build line",
							TextEdits: []analysis.TextEdit{{
								Pos: c.Pos(),
								End: c.End(),
							}},
						}},
					})
					break
				}
				if strings.HasPrefix(c.Text, "//go:build ") {
					sawGoBuild = true
				}
			}
		}
	}

	for _, f := range pass.Files {
		check(f)
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments|parser.SkipObjectResolution)
			if err != nil {
				continue
			}
			check(f)
		}
	}
	return nil, nil
}

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var RangeIntAnalyzer = &analysis.Analyzer{
	Name: "rangeint",
	Doc:  analyzerutil.MustExtractDoc(doc, "rangeint"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: rangeint,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#rangeint",
}

// rangeint offers a fix to replace a 3-clause 'for' loop:
//
// for i := 0; i < limit; i++ {}
//
// by a range loop with an integer operand:
//
// for i := range limit {}
func rangeint(pass *analysis.Pass) (any, error) {
	var (
		info      = pass.TypesInfo
		typeindex = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	)

	for curFile := range filesUsingGoVersion(pass, versions.Go1_22) {
	nextLoop:
		for curLoop := range curFile.Preorder((*ast.ForStmt)(nil)) {
			loop := curLoop.Node().(*ast.ForStmt)
			if init, ok := loop.Init.(*ast.AssignStmt); ok &&
				isSimpleAssign(init) &&
				is[*ast.Ident](init.Lhs[0]) &&
				isZeroIntConst(info, init.Rhs[0]) {
				// Have: for i = 0; ... (or i := 0)
				index := init.Lhs[0].(*ast.Ident)

				if compare, ok := loop.Cond.(*ast.BinaryExpr); ok &&
					compare.Op == token.LSS &&
					astutil.EqualSyntax(compare.X, init.Lhs[0]) {
					// Have: for i = 0; i < limit; ... {}

					limit := compare.Y

					// If limit is "len(slice)", simplify it to "slice".
					if call, ok := limit.(*ast.CallExpr); ok &&
						typeutil.Callee(info, call) == builtinLen &&
						is[*types.Slice](info.TypeOf(call.Args[0]).Underlying()) {
						limit = call.Args[0]
					}

					// Check the form of limit: must be a constant,
					// or a local var that is not assigned or address-taken.
					limitOK := false
					if info.Types[limit].Value != nil {
						limitOK = true // constant
					} else if id, ok := limit.(*ast.Ident); ok {
						if v, ok := info.Uses[id].(*types.Var); ok &&
							!(v.Exported() && typesinternal.IsPackageLevel(v)) {
							// limit is a local or unexported global var.
							for cur := range typeindex.Uses(v) {
								if isScalarLvalue(info, cur) {
									// Limit var is assigned or address-taken.
									continue nextLoop
								}
							}
							limitOK = true
						}
					}
					if !limitOK {
						continue nextLoop
					}

					validIncrement := false
					if inc, ok := loop.Post.(*ast.IncDecStmt); ok &&
						inc.Tok == token.INC &&
						astutil.EqualSyntax(compare.X, inc.X) {
						// Have: i++
						validIncrement = true
					} else if assign, ok := loop.Post.(*ast.AssignStmt); ok &&
						assign.Tok == token.ADD_ASSIGN &&
						len(assign.Rhs) == 1 && isIntLiteral(info, assign.Rhs[0], 1) &&
						len(assign.Lhs) == 1 && astutil.EqualSyntax(compare.X, assign.Lhs[0]) {
						// Have: i += 1
						validIncrement = true
					}

					if validIncrement {
						// Have: for i = 0; i < limit; i++ {}

						// Find references to i within the loop body.
						v := info.ObjectOf(index).(*types.Var)
						if typesinternal.IsPackageLevel(v) {
							continue nextLoop
						}

						// If v is a named result, it is implicitly
						// used after the loop (go.dev/issue/76880).
						if moreiters.Contains(enclosingSignature(curLoop, info).Results().Variables(), v) {
							continue nextLoop
						}

						used := false
						for curId := range curLoop.Child(loop.Body).Preorder((*ast.Ident)(nil)) {
							id := curId.Node().(*ast.Ident)
							if info.Uses[id] == v {
								used = true

								// Reject if any is an l-value (assigned or address-taken):
								// a "for range int" loop does not respect assignments to
								// the loop variable.
								if isScalarLvalue(info, curId) {
									continue nextLoop
								}
							}
						}

						// If i is no longer used, delete "i := ".
						var edits []analysis.TextEdit
						if !used && init.Tok == token.DEFINE {
							edits = append(edits, analysis.TextEdit{
								Pos: index.Pos(),
								End: init.Rhs[0].Pos(),
							})
						}

						pass.Report(analysis.Diagnostic{
							Pos:     init.Pos(),
							End:     loop.Post.End(),
							Message: "for loop can be modernized using range over int",
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: fmt.Sprintf("Replace for loop with range %s",
									astutil.Format(pass.Fset, limit)),
								TextEdits: append(edits, []analysis.TextEdit{
									// for i := 0; i < limit; i++ {}
									// ----- ---
									// -------
									// for i := range limit {}

									// Delete init.
									{
										Pos:     init.Rhs[0].Pos(),
										End:     limit.Pos(),
										NewText: []byte("range "),
									},
									// Delete inc.
									{
										Pos:     limit.End(),
										End:     loop.Post.End(),
									},
								}...),
							}},
						})
					}
				}
			}
		}
	}
	return nil, nil
}

// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

// This file defines modernizers that use the "reflect" package.

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var ReflectTypeForAnalyzer = &analysis.Analyzer{
	Name: "reflecttypefor",
	Doc:  analyzerutil.MustExtractDoc(doc, "reflecttypefor"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: reflecttypefor,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#reflecttypefor",
}

func reflecttypefor(pass *analysis.Pass) (any, error) {
	var (
		index         = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info          = pass.TypesInfo
		reflectTypeOf = index.Object("reflect", "TypeOf")
	)

	for curCall := range index.Calls(reflectTypeOf) {
		call := curCall.Node().(*ast.CallExpr)
		// Have: reflect.TypeOf(expr)

		expr := call.Args[0]
		if !typesinternal.NoEffects(info, expr) {
			continue // don't eliminate operand: may have effects
		}

		t := info.TypeOf(expr)
		var edits []analysis.TextEdit

		// Special case for TypeOf((*T)(nil)).Elem(),
		// needed when T is an interface type.
		if astutil.IsChildOf(curCall, edge.SelectorExpr_X) {
			curSel := unparenEnclosing(curCall).Parent()
			if astutil.IsChildOf(curSel, edge.CallExpr_Fun) {
				call2 := unparenEnclosing(curSel).Parent().Node().(*ast.CallExpr)
				obj := typeutil.Callee(info, call2)
				if typesinternal.IsMethodNamed(obj, "reflect", "Type", "Elem") {
					if ptr, ok := t.(*types.Pointer); ok {
						t = ptr.Elem()
						edits = []analysis.TextEdit{{
							Pos: call.End(),
							End: call2.End(),
						}}
					}
				}
			}
		}

		// TypeOf(x) where x has an interface type is a
		// dynamic operation; don't transform it to TypeFor.
		if types.IsInterface(t) && edits == nil {
			continue
		}

		file := astutil.EnclosingFile(curCall)
		if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_22) {
			continue
		}
		tokFile := pass.Fset.File(file.Pos())

		qual := typesinternal.FileQualifier(file, pass.Pkg)
		tstr := types.TypeString(t, qual)

		sel, ok := call.Fun.(*ast.SelectorExpr)
		if !ok {
			continue
		}

		if isComplicatedType(t) {
			continue
		}

		oldLen := int(expr.End() - expr.Pos())
		newLen := len(tstr)
		if newLen >= 16 && newLen > 3*oldLen {
			continue
		}

		curArg0 := curCall.ChildAt(edge.CallExpr_Args, 0)
		edits = append(edits, refactor.DeleteUnusedVars(index, info, tokFile, curArg0)...)

		pass.Report(analysis.Diagnostic{
			Pos:     call.Fun.Pos(),
			End:     call.Fun.End(),
			Message: "reflect.TypeOf call can be simplified using TypeFor",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Replace TypeOf by TypeFor",
				TextEdits: append([]analysis.TextEdit{
					{
						Pos:     sel.Sel.Pos(),
						End:     sel.Sel.End(),
						NewText: []byte("TypeFor[" + tstr + "]"),
					},
					{
						Pos: call.Lparen + 1,
						End: call.Rparen,
					},
				}, edits...),
			}},
		})
	}

	return nil, nil
}

// isComplicatedType reports whether type t is complicated, e.g. it is or contains an
// unnamed struct, interface, or function signature.
func isComplicatedType(t types.Type) bool {
	var check func(typ types.Type) bool
	check = func(typ types.Type) bool {
		switch t := typ.(type) {
		case typesinternal.NamedOrAlias:
			for ta := range t.TypeArgs().Types() {
				if check(ta) {
					return true
				}
			}
			return false
		case *types.Struct, *types.Interface, *types.Signature:
			return true
		case *types.Pointer:
			return check(t.Elem())
		case *types.Slice:
			return check(t.Elem())
		case *types.Array:
			return check(t.Elem())
		case *types.Chan:
			return check(t.Elem())
		case *types.Map:
			return check(t.Key()) || check(t.Elem())
		case *types.Basic:
			return false
		case *types.TypeParam:
			return false
		default:
			return true
		}
	}

	return check(t)
}

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var SlicesContainsAnalyzer = &analysis.Analyzer{
	Name: "slicescontains",
	Doc:  analyzerutil.MustExtractDoc(doc, "slicescontains"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: slicescontains,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicescontains",
}

// The slicescontains pass identifies loops that can be replaced by a
// call to slices.Contains{,Func}. For example:
//
// for i, elem := range s {
// if elem == needle {
// ...
// break
// }
// }
//
// =>
//
// if slices.Contains(s, needle) { ... }
func slicescontains(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "runtime") {
		return nil, nil
	}

	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	// check is called for each RangeStmt of this form:
	// for i, elem := range s { if cond { ... } }
	check := func(file *ast.File, curRange inspector.Cursor) {
		rng := curRange.Node().(*ast.RangeStmt)
		ifStmt := rng.Body.List[0].(*ast.IfStmt)

		// isSliceElem reports whether e denotes the
		// current slice element (elem or s[i]).
		isSliceElem := func(e ast.Expr) bool {
			if rng.Value != nil && astutil.EqualSyntax(e, rng.Value) {
				return true // "elem"
			}
			if x, ok := e.(*ast.IndexExpr); ok &&
				astutil.EqualSyntax(x.X, rng.X) &&
				astutil.EqualSyntax(x.Index, rng.Key) {
				return true // "s[i]"
			}
			return false
		}

		// Examine the condition for one of these forms:
		//
		// - if elem or s[i] == needle { ... } => Contains
		// - if predicate(s[i] or elem) { ... } => ContainsFunc
		var (
			funcName string // "Contains" or "ContainsFunc"
			arg2     ast.Expr // second argument to func (needle or predicate)
		)
		switch cond := ifStmt.Cond.(type) {
		case *ast.BinaryExpr:
			if cond.Op == token.EQL {
				var elem ast.Expr
				if isSliceElem(cond.X) {
					funcName = "Contains"
					elem = cond.X
					arg2 = cond.Y // "if elem == needle"
				} else if isSliceElem(cond.Y) {
					funcName = "Contains"
					elem = cond.Y
					arg2 = cond.X // "if needle == elem"
				}

				// Reject if elem and needle have different types.
				if elem != nil {
					tElem := info.TypeOf(elem)
					tNeedle := info.TypeOf(arg2)
					if !types.Identical(tElem, tNeedle) {
						if !types.AssignableTo(tNeedle, tElem) {
							return
						}
						return
					}
				}
			}

		case *ast.CallExpr:
			if len(cond.Args) == 1 &&
				isSliceElem(cond.Args[0]) &&
				typeutil.Callee(info, cond) != nil {

				sig, isSignature := info.TypeOf(cond.Fun).(*types.Signature)
				if isSignature {
					if sig.Variadic() {
						return
					}

					var (
						tElem  = typeparams.CoreType(info.TypeOf(rng.X)).(*types.Slice).Elem()
						tParam = sig.Params().At(0).Type()
					)
					if !types.Identical(tElem, tParam) {
						return
					}
				}

				funcName = "ContainsFunc"
				arg2 = cond.Fun // "if predicate(elem)"
			}
		}
		if funcName == "" {
			return // not a candidate for Contains{,Func}
		}

		// Prepare slices.Contains{,Func} call.
		prefix, importEdits := refactor.AddImport(info, file, "slices", "slices", funcName, rng.Pos())
		contains := fmt.Sprintf("%s%s(%s, %s)",
			prefix,
			funcName,
			astutil.Format(pass.Fset, rng.X),
			astutil.Format(pass.Fset, arg2))

		report := func(edits []analysis.TextEdit) {
			pass.Report(analysis.Diagnostic{
				Pos:     rng.Pos(),
				End:     rng.End(),
				Message: fmt.Sprintf("Loop can be simplified using slices.%s", funcName),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: "Replace loop by call to slices." + funcName,
					TextEdits: append(edits, importEdits...),
				}},
			})
		}

		// Last statement of body must return/break out of the loop.
		curBody, _ := curRange.FindNode(ifStmt.Body)
		curLastStmt, _ := curBody.LastChild()

		switch lastStmt := curLastStmt.Node().(type) {
		case *ast.ReturnStmt:
			// Have: for ... range seq { if ... { stmts; return x } }
			report([]analysis.TextEdit{
				// Replace "for ... { if ... " with "if slices.Contains(...)".
				{
					Pos:     rng.Pos(),
					End:     ifStmt.Body.Pos(),
					NewText: fmt.Appendf(nil, "if %s ", contains),
				},
				// Delete '}' of range statement and preceding space.
				{
					Pos: ifStmt.Body.End(),
					End: rng.End(),
				},
			})
			return

		case *ast.BranchStmt:
			if lastStmt.Tok == token.BREAK && lastStmt.Label == nil {
				// Have: for ... { if ... { stmts; break } }
				report([]analysis.TextEdit{
					// Replace "for ... { if ... " with "if slices.Contains(...)".
					{
						Pos:     rng.Pos(),
						End:     ifStmt.Body.Pos(),
						NewText: fmt.Appendf(nil, "if %s ", contains),
					},
					// Delete break statement and preceding space.
					{
						Pos: func() token.Pos {
							if len(ifStmt.Body.List) > 1 {
								beforeBreak, _ := curLastStmt.PrevSibling()
								return beforeBreak.Node().End()
							}
							return lastStmt.Pos()
						}(),
						End: lastStmt.End(),
					},
					// Delete '}' of range statement and preceding space.
					{
						Pos: ifStmt.Body.End(),
						End: rng.End(),
					},
				})
				return
			}
		}
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_21) {
		file := curFile.Node().(*ast.File)

		for curRange := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			rng := curRange.Node().(*ast.RangeStmt)

			if is[*ast.Ident](rng.Key) &&
				rng.Tok == token.DEFINE &&
				len(rng.Body.List) == 1 &&
				is[*types.Slice](typeparams.CoreType(info.TypeOf(rng.X))) {

				if ifStmt, ok := rng.Body.List[0].(*ast.IfStmt); ok &&
					ifStmt.Init == nil && ifStmt.Else == nil {

					// Have: for i, elem := range s { if cond { ... } }
					check(file, curRange)
				}
			}
		}
	}
	return nil, nil
}

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

// (Not to be confused with go/analysis/passes/sortslice.)
var SlicesSortAnalyzer = &analysis.Analyzer{
	Name: "slicessort",
	Doc:  analyzerutil.MustExtractDoc(doc, "slicessort"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: slicessort,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicessort",
}

// The slicessort pass replaces sort.Slice(slice, less) with
// slices.Sort(slice) when slice is a []T and less is a FuncLit
// equivalent to cmp.Ordered[T].
func slicessort(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "sort", "runtime") {
		return nil, nil
	}

	var (
		info      = pass.TypesInfo
		index     = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		sortSlice = index.Object("sort", "Slice")
	)
	for curCall := range index.Calls(sortSlice) {
		call := curCall.Node().(*ast.CallExpr)
		if lit, ok := call.Args[1].(*ast.FuncLit); ok && len(lit.Body.List) == 1 {
			sig := pass.TypesInfo.Types[lit.Type].Type.(*types.Signature)

			// Have: sort.Slice(s, func(i, j int) bool { return ... })
			s := call.Args[0]
			i := sig.Params().At(0)
			j := sig.Params().At(1)

			if ret, ok := lit.Body.List[0].(*ast.ReturnStmt); ok {
				if compare, ok := ret.Results[0].(*ast.BinaryExpr); ok && compare.Op == token.LSS {
					// isIndex reports whether e is s[v].
					isIndex := func(e ast.Expr, v *types.Var) bool {
						index, ok := e.(*ast.IndexExpr)
						return ok &&
							astutil.EqualSyntax(index.X, s) &&
							is[*ast.Ident](index.Index) &&
							pass.TypesInfo.Uses[index.Index.(*ast.Ident)] == v
					}
					file := astutil.EnclosingFile(curCall)
					if isIndex(compare.X, i) && isIndex(compare.Y, j) &&
						analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_21) {
						// Have: sort.Slice(s, func(i, j int) bool { return s[i] < s[j] })

						prefix, importEdits := refactor.AddImport(
							info, file, "slices", "slices", "Sort", call.Pos())

						pass.Report(analysis.Diagnostic{
							Pos:     call.Fun.Pos(),
							End:     call.Fun.End(),
							Message: "sort.Slice can be modernized using slices.Sort",
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: "Replace sort.Slice call by slices.Sort",
								TextEdits: append(importEdits, []analysis.TextEdit{
									{
										Pos:     call.Fun.Pos(),
										End:     call.Fun.End(),
										NewText: []byte(prefix + "Sort"),
									},
									{
										Pos:     call.Args[0].End(),
										End:     call.Rparen,
									},
								}...),
							}},
						})
					}
				}
			}
		}
	}
	return nil, nil
}