Update to go1.24.2

src/cmd/compile/internal/inline/inl.go

@@ -42,6 +42,7 @@ import (
 	"cmd/compile/internal/types"
 	"cmd/internal/obj"
 	"cmd/internal/pgo"
+	"cmd/internal/src"
 )
 
 // Inlining budget parameters, gathered in one place
@@ -974,6 +975,16 @@ func inlineCostOK(n *ir.CallExpr, caller, callee *ir.Func, bigCaller, closureCal
 	return true, 0, metric, hot
 }
 
+// parsePos returns all the inlining positions and the innermost position.
+func parsePos(pos src.XPos, posTmp []src.Pos) ([]src.Pos, src.Pos) {
+	ctxt := base.Ctxt
+	ctxt.AllPos(pos, func(p src.Pos) {
+		posTmp = append(posTmp, p)
+	})
+	l := len(posTmp) - 1
+	return posTmp[:l], posTmp[l]
+}
+
 // canInlineCallExpr returns true if the call n from caller to callee
 // can be inlined, plus the score computed for the call expr in question,
 // and whether the callee is hot according to PGO.
@@ -1001,6 +1012,17 @@ func canInlineCallExpr(callerfn *ir.Func, n *ir.CallExpr, callee *ir.Func, bigCa
 		return false, 0, false
 	}
 
+	callees, calleeInner := parsePos(n.Pos(), make([]src.Pos, 0, 10))
+
+	for _, p := range callees {
+		if p.Line() == calleeInner.Line() && p.Col() == calleeInner.Col() && p.AbsFilename() == calleeInner.AbsFilename() {
+			if log && logopt.Enabled() {
+				logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", fmt.Sprintf("recursive call to %s", ir.FuncName(callerfn)))
+			}
+			return false, 0, false
+		}
+	}
+
 	if callee == callerfn {
 		// Can't recursively inline a function into itself.
 		if log && logopt.Enabled() {

src/cmd/compile/internal/inline/interleaved/interleaved.go

@@ -253,7 +253,7 @@ func (s *inlClosureState) mark(n ir.Node) ir.Node {
 
 	if isTestingBLoop(n) {
 		// No inlining nor devirtualization performed on b.Loop body
-		if base.Flag.LowerM > 1 {
+		if base.Flag.LowerM > 0 {
 			fmt.Printf("%v: skip inlining within testing.B.loop for %v\n", ir.Line(n), n)
 		}
 		// We still want to explore inlining opportunities in other parts of ForStmt.

src/cmd/compile/internal/test/inl_test.go

@@ -230,6 +230,9 @@ func TestIntendedInlining(t *testing.T) {
 			"(*Pointer[go.shape.int]).Store",
 			"(*Pointer[go.shape.int]).Swap",
 		},
+		"testing": {
+			"(*B).Loop",
+		},
 	}
 
 	if !goexperiment.SwissMap {

src/cmd/compile/internal/types2/assignments.go

@@ -204,7 +204,7 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
 			// dot-imported variables.
 			if w, _ := obj.(*Var); w != nil && w.pkg == check.pkg {
 				v = w
-				v_used = v.used
+				v_used = check.usedVars[v]
 			}
 		}
 	}
@@ -213,7 +213,7 @@ func (check *Checker) lhsVar(lhs syntax.Expr) Type {
 	check.expr(nil, &x, lhs)
 
 	if v != nil {
-		v.used = v_used // restore v.used
+		check.usedVars[v] = v_used // restore v.used
 	}
 
 	if x.mode == invalid || !isValid(x.typ) {

src/cmd/compile/internal/types2/call.go

@@ -687,7 +687,7 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, def *TypeName
 		if pname, _ := obj.(*PkgName); pname != nil {
 			assert(pname.pkg == check.pkg)
 			check.recordUse(ident, pname)
-			pname.used = true
+			check.usedPkgNames[pname] = true
 			pkg := pname.imported
 
 			var exp Object
@@ -972,13 +972,13 @@ func (check *Checker) use1(e syntax.Expr, lhs bool) bool {
 				// dot-imported variables.
 				if w, _ := obj.(*Var); w != nil && w.pkg == check.pkg {
 					v = w
-					v_used = v.used
+					v_used = check.usedVars[v]
 				}
 			}
 		}
 		check.exprOrType(&x, n, true)
 		if v != nil {
-			v.used = v_used // restore v.used
+			check.usedVars[v] = v_used // restore v.used
 		}
 	case *syntax.ListExpr:
 		return check.useN(n.ElemList, lhs)

src/cmd/compile/internal/types2/check.go

@@ -162,6 +162,8 @@ type Checker struct {
 	dotImportMap  map[dotImportKey]*PkgName  // maps dot-imported objects to the package they were dot-imported through
 	brokenAliases map[*TypeName]bool         // set of aliases with broken (not yet determined) types
 	unionTypeSets map[*Union]*_TypeSet       // computed type sets for union types
+	usedVars      map[*Var]bool              // set of used variables
+	usedPkgNames  map[*PkgName]bool          // set of used package names
 	mono          monoGraph                  // graph for detecting non-monomorphizable instantiation loops
 
 	firstErr error                    // first error encountered
@@ -285,12 +287,14 @@ func NewChecker(conf *Config, pkg *Package, info *Info) *Checker {
 	// (previously, pkg.goVersion was mutated here: go.dev/issue/61212)
 
 	return &Checker{
-		conf:   conf,
-		ctxt:   conf.Context,
-		pkg:    pkg,
-		Info:   info,
-		objMap: make(map[Object]*declInfo),
-		impMap: make(map[importKey]*Package),
+		conf:         conf,
+		ctxt:         conf.Context,
+		pkg:          pkg,
+		Info:         info,
+		objMap:       make(map[Object]*declInfo),
+		impMap:       make(map[importKey]*Package),
+		usedVars:     make(map[*Var]bool),
+		usedPkgNames: make(map[*PkgName]bool),
 	}
 }
 
@@ -298,6 +302,8 @@ func NewChecker(conf *Config, pkg *Package, info *Info) *Checker {
 // The provided files must all belong to the same package.
 func (check *Checker) initFiles(files []*syntax.File) {
 	// start with a clean slate (check.Files may be called multiple times)
+	// TODO(gri): what determines which fields are zeroed out here, vs at the end
+	// of checkFiles?
 	check.files = nil
 	check.imports = nil
 	check.dotImportMap = nil
@@ -309,6 +315,13 @@ func (check *Checker) initFiles(files []*syntax.File) {
 	check.objPath = nil
 	check.cleaners = nil
 
+	// We must initialize usedVars and usedPkgNames both here and in NewChecker,
+	// because initFiles is not called in the CheckExpr or Eval codepaths, yet we
+	// want to free this memory at the end of Files ('used' predicates are
+	// only needed in the context of a given file).
+	check.usedVars = make(map[*Var]bool)
+	check.usedPkgNames = make(map[*PkgName]bool)
+
 	// determine package name and collect valid files
 	pkg := check.pkg
 	for _, file := range files {
@@ -482,8 +495,11 @@ func (check *Checker) checkFiles(files []*syntax.File) {
 	check.seenPkgMap = nil
 	check.brokenAliases = nil
 	check.unionTypeSets = nil
+	check.usedVars = nil
+	check.usedPkgNames = nil
 	check.ctxt = nil
 
+	// TODO(gri): shouldn't the cleanup above occur after the bailout?
 	// TODO(gri) There's more memory we should release at this point.
 }
 

src/cmd/compile/internal/types2/object.go

@@ -242,13 +242,12 @@ func (a *object) cmp(b *object) int {
 type PkgName struct {
 	object
 	imported *Package
-	used     bool // set if the package was used
 }
 
 // NewPkgName returns a new PkgName object representing an imported package.
 // The remaining arguments set the attributes found with all Objects.
 func NewPkgName(pos syntax.Pos, pkg *Package, name string, imported *Package) *PkgName {
-	return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, black, nopos}, imported, false}
+	return &PkgName{object{nil, pos, pkg, name, Typ[Invalid], 0, black, nopos}, imported}
 }
 
 // Imported returns the package that was imported.
@@ -331,10 +330,10 @@ func (obj *TypeName) IsAlias() bool {
 // A Variable represents a declared variable (including function parameters and results, and struct fields).
 type Var struct {
 	object
+	origin   *Var // if non-nil, the Var from which this one was instantiated
 	embedded bool // if set, the variable is an embedded struct field, and name is the type name
 	isField  bool // var is struct field
-	used     bool // set if the variable was used
-	origin   *Var // if non-nil, the Var from which this one was instantiated
+	isParam  bool // var is a param, for backport of 'used' check to go1.24 (go.dev/issue/72826)
 }
 
 // NewVar returns a new variable.
@@ -345,7 +344,7 @@ func NewVar(pos syntax.Pos, pkg *Package, name string, typ Type) *Var {
 
 // NewParam returns a new variable representing a function parameter.
 func NewParam(pos syntax.Pos, pkg *Package, name string, typ Type) *Var {
-	return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, used: true} // parameters are always 'used'
+	return &Var{object: object{nil, pos, pkg, name, typ, 0, colorFor(typ), nopos}, isParam: true}
 }
 
 // NewField returns a new variable representing a struct field.

src/cmd/compile/internal/types2/resolver.go

@@ -295,7 +295,7 @@ func (check *Checker) collectObjects() {
 
 				if imp.fake {
 					// match 1.17 cmd/compile (not prescribed by spec)
-					pkgName.used = true
+					check.usedPkgNames[pkgName] = true
 				}
 
 				// add import to file scope
@@ -715,7 +715,7 @@ func (check *Checker) unusedImports() {
 	// (initialization), use the blank identifier as explicit package name."
 
 	for _, obj := range check.imports {
-		if !obj.used && obj.name != "_" {
+		if obj.name != "_" && !check.usedPkgNames[obj] {
 			check.errorUnusedPkg(obj)
 		}
 	}

src/cmd/compile/internal/types2/sizeof_test.go

@@ -36,7 +36,7 @@ func TestSizeof(t *testing.T) {
 		{term{}, 12, 24},
 
 		// Objects
-		{PkgName{}, 64, 104},
+		{PkgName{}, 60, 96},
 		{Const{}, 64, 104},
 		{TypeName{}, 56, 88},
 		{Var{}, 64, 104},

src/cmd/compile/internal/types2/stmt.go

@@ -58,7 +58,7 @@ func (check *Checker) usage(scope *Scope) {
 	var unused []*Var
 	for name, elem := range scope.elems {
 		elem = resolve(name, elem)
-		if v, _ := elem.(*Var); v != nil && !v.used {
+		if v, _ := elem.(*Var); v != nil && !v.isParam && !check.usedVars[v] {
 			unused = append(unused, v)
 		}
 	}
@@ -824,10 +824,10 @@ func (check *Checker) typeSwitchStmt(inner stmtContext, s *syntax.SwitchStmt, gu
 	if lhs != nil {
 		var used bool
 		for _, v := range lhsVars {
-			if v.used {
+			if check.usedVars[v] {
 				used = true
 			}
-			v.used = true // avoid usage error when checking entire function
+			check.usedVars[v] = true // avoid usage error when checking entire function
 		}
 		if !used {
 			check.softErrorf(lhs, UnusedVar, "%s declared and not used", lhs.Value)
@@ -934,7 +934,7 @@ func (check *Checker) rangeStmt(inner stmtContext, s *syntax.ForStmt, rclause *s
 			if typ == nil || typ == Typ[Invalid] {
 				// typ == Typ[Invalid] can happen if allowVersion fails.
 				obj.typ = Typ[Invalid]
-				obj.used = true // don't complain about unused variable
+				check.usedVars[obj] = true // don't complain about unused variable
 				continue
 			}
 

src/cmd/compile/internal/types2/typexpr.go

@@ -55,7 +55,7 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *TypeName, wantType
 		// avoid "declared but not used" errors
 		// (don't use Checker.use - we don't want to evaluate too much)
 		if v, _ := obj.(*Var); v != nil && v.pkg == check.pkg /* see Checker.use1 */ {
-			v.used = true
+			check.usedVars[v] = true
 		}
 		return
 	}
@@ -83,7 +83,7 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *TypeName, wantType
 	// (This code is only needed for dot-imports. Without them,
 	// we only have to mark variables, see *Var case below).
 	if pkgName := check.dotImportMap[dotImportKey{scope, obj.Name()}]; pkgName != nil {
-		pkgName.used = true
+		check.usedPkgNames[pkgName] = true
 	}
 
 	switch obj := obj.(type) {
@@ -120,7 +120,7 @@ func (check *Checker) ident(x *operand, e *syntax.Name, def *TypeName, wantType
 		// from other packages to avoid potential race conditions with
 		// dot-imported variables.
 		if obj.pkg == check.pkg {
-			obj.used = true
+			check.usedVars[obj] = true
 		}
 		check.addDeclDep(obj)
 		if !isValid(typ) {

src/cmd/internal/objabi/pkgspecial.go

@@ -43,6 +43,9 @@ type PkgSpecial struct {
 }
 
 var runtimePkgs = []string{
+	// TODO(panjf2000): consider syncing the list inside the
+	// 	isAsyncSafePoint in preempt.go based on this list?
+
 	"runtime",
 
 	"internal/runtime/atomic",