go/ssa/instantiate_test.go - tools - Git at Google

 // Copyright 2022 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 ssa_test

 import (
 	"fmt"
 	"go/types"
 	"reflect"
 	"sort"
 	"strings"
 	"testing"

 	"golang.org/x/tools/go/ssa"
 	"golang.org/x/tools/go/ssa/ssautil"
 )

 // TestNeedsInstance ensures that new method instances can be created via MethodValue.
 func TestNeedsInstance(t *testing.T) {
 	const input = `
 package p

 import "unsafe"

 type Pointer[T any] struct {
 	v unsafe.Pointer
 }

 func (x *Pointer[T]) Load() *T {
 	return (*T)(LoadPointer(&x.v))
 }

 func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
 `
 	// The SSA members for this package should look something like this:
 	//      func  LoadPointer func(addr *unsafe.Pointer) (val unsafe.Pointer)
 	//      type  Pointer     struct{v unsafe.Pointer}
 	//        method (*Pointer[T any]) Load() *T
 	//      func  init        func()
 	//      var   init$guard  bool

 	for _, mode := range []ssa.BuilderMode{
 		ssa.SanityCheckFunctions,
 		ssa.SanityCheckFunctions | ssa.InstantiateGenerics,
 	} {
 		p, _ := buildPackage(t, input, mode)
 		prog := p.Prog

 		ptr := p.Type("Pointer").Type().(*types.Named)
 		if ptr.NumMethods() != 1 {
 			t.Fatalf("Expected Pointer to have 1 method. got %d", ptr.NumMethods())
 		}

 		obj := ptr.Method(0)
 		if obj.Name() != "Load" {
 			t.Errorf("Expected Pointer to have method named 'Load'. got %q", obj.Name())
 		}

 		meth := prog.FuncValue(obj)

 		// instantiateLoadMethod returns the first method (Load) of the instantiation *Pointer[T].
 		instantiateLoadMethod := func(T types.Type) *ssa.Function {
 			ptrT, err := types.Instantiate(nil, ptr, []types.Type{T}, false)
 			if err != nil {
 				t.Fatalf("Failed to Instantiate %q by %q", ptr, T)
 			}
 			methods := types.NewMethodSet(types.NewPointer(ptrT))
 			if methods.Len() != 1 {
 				t.Fatalf("Expected 1 method for %q. got %d", ptrT, methods.Len())
 			}
 			return prog.MethodValue(methods.At(0))
 		}

 		intSliceTyp := types.NewSlice(types.Typ[types.Int])
 		instance := instantiateLoadMethod(intSliceTyp) // (*Pointer[[]int]).Load
 		if instance.Origin() != meth {
 			t.Errorf("Expected Origin of %s to be %s. got %s", instance, meth, instance.Origin())
 		}
 		if len(instance.TypeArgs()) != 1 || !types.Identical(instance.TypeArgs()[0], intSliceTyp) {
 			t.Errorf("Expected TypeArgs of %s to be %v. got %v", instance, []types.Type{intSliceTyp}, instance.TypeArgs())
 		}

 		// A second request with an identical type returns the same Function.
 		second := instantiateLoadMethod(types.NewSlice(types.Typ[types.Int]))
 		if second != instance {
 			t.Error("Expected second identical instantiation to be the same function")
 		}

 		// (*Pointer[[]uint]).Load
 		inst2 := instantiateLoadMethod(types.NewSlice(types.Typ[types.Uint]))

 		if instance.Name() >= inst2.Name() {
 			t.Errorf("Expected name of instance %s to be before instance %v", instance, inst2)
 		}
 	}
 }

 // TestCallsToInstances checks that calles of calls to generic functions,
 // without monomorphization, are wrappers around the origin generic function.
 func TestCallsToInstances(t *testing.T) {
 	const input = `
 package p

 type I interface {
 	Foo()
 }

 type A int
 func (a A) Foo() {}

 type J[T any] interface{ Bar() T }
 type K[T any] struct{ J[T] }

 func Id[T any] (t T) T {
 	return t
 }

 func Lambda[T I]() func() func(T) {
 	return func() func(T) {
 		return T.Foo
 	}
 }

 func NoOp[T any]() {}

 func Bar[T interface { Foo(); ~int | ~string }, U any] (t T, u U) {
 	Id[U](u)
 	Id[T](t)
 }

 func Make[T any]() interface{} {
 	NoOp[K[T]]()
 	return nil
 }

 func entry(i int, a A) int {
 	Lambda[A]()()(a)

 	x := Make[int]()
 	if j, ok := x.(interface{ Bar() int }); ok {
 		print(j)
 	}

 	Bar[A, int](a, i)

 	return Id[int](i)
 }
 `
 	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)
 	all := ssautil.AllFunctions(p.Prog)

 	for _, ti := range []struct {
 		orig         string
 		instance     string
 		tparams      string
 		targs        string
 		chTypeInstrs int // number of ChangeType instructions in f's body
 	}{
 		{"Id", "Id[int]", "[T]", "[int]", 2},
 		{"Lambda", "Lambda[p.A]", "[T]", "[p.A]", 1},
 		{"Make", "Make[int]", "[T]", "[int]", 0},
 		{"NoOp", "NoOp[p.K[T]]", "[T]", "[p.K[T]]", 0},
 	} {
 		test := ti
 		t.Run(test.instance, func(t *testing.T) {
 			f := p.Members[test.orig].(*ssa.Function)
 			if f == nil {
 				t.Fatalf("origin function not found")
 			}

 			var i *ssa.Function
 			for _, fn := range instancesOf(all, f) {
 				if fn.Name() == test.instance {
 					i = fn
 					break
 				}
 			}
 			if i == nil {
 				t.Fatalf("instance not found")
 			}

 			// for logging on failures
 			var body strings.Builder
 			i.WriteTo(&body)
 			t.Log(body.String())

 			if len(i.Blocks) != 1 {
 				t.Fatalf("body has more than 1 block")
 			}

 			if instrs := changeTypeInstrs(i.Blocks[0]); instrs != test.chTypeInstrs {
 				t.Errorf("want %v instructions; got %v", test.chTypeInstrs, instrs)
 			}

 			if test.tparams != tparams(i) {
 				t.Errorf("want %v type params; got %v", test.tparams, tparams(i))
 			}

 			if test.targs != targs(i) {
 				t.Errorf("want %v type arguments; got %v", test.targs, targs(i))
 			}
 		})
 	}
 }

 func tparams(f *ssa.Function) string {
 	tplist := f.TypeParams()
 	var tps []string
 	for i := 0; i < tplist.Len(); i++ {
 		tps = append(tps, tplist.At(i).String())
 	}
 	return fmt.Sprint(tps)
 }

 func targs(f *ssa.Function) string {
 	var tas []string
 	for _, ta := range f.TypeArgs() {
 		tas = append(tas, ta.String())
 	}
 	return fmt.Sprint(tas)
 }

 func changeTypeInstrs(b *ssa.BasicBlock) int {
 	cnt := 0
 	for _, i := range b.Instrs {
 		if _, ok := i.(*ssa.ChangeType); ok {
 			cnt++
 		}
 	}
 	return cnt
 }

 func TestInstanceUniqueness(t *testing.T) {
 	const input = `
 package p

 func H[T any](t T) {
 	print(t)
 }

 func F[T any](t T) {
 	H[T](t)
 	H[T](t)
 	H[T](t)
 }

 func G[T any](t T) {
 	H[T](t)
 	H[T](t)
 }

 func Foo[T any, S any](t T, s S) {
 	Foo[S, T](s, t)
 	Foo[T, S](t, s)
 }
 `
 	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)

 	all := ssautil.AllFunctions(p.Prog)
 	for _, test := range []struct {
 		orig      string
 		instances string
 	}{
 		{"H", "[p.H[T] p.H[T]]"},
 		{"Foo", "[p.Foo[S T] p.Foo[T S]]"},
 	} {
 		t.Run(test.orig, func(t *testing.T) {
 			f := p.Members[test.orig].(*ssa.Function)
 			if f == nil {
 				t.Fatalf("origin function not found")
 			}

 			instances := instancesOf(all, f)
 			sort.Slice(instances, func(i, j int) bool { return instances[i].Name() < instances[j].Name() })

 			if got := fmt.Sprintf("%v", instances); !reflect.DeepEqual(got, test.instances) {
 				t.Errorf("got %v instances, want %v", got, test.instances)
 			}
 		})
 	}
 }

 // instancesOf returns a new unordered slice of all instances of the
 // specified function g in fns.
 func instancesOf(fns map[*ssa.Function]bool, g *ssa.Function) []*ssa.Function {
 	var instances []*ssa.Function
 	for fn := range fns {
 		if fn != g && fn.Origin() == g {
 			instances = append(instances, fn)
 		}
 	}
 	return instances
 }
	// Copyright 2022 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 ssa_test

	import (
	"fmt"
	"go/types"
	"reflect"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	)

	// TestNeedsInstance ensures that new method instances can be created via MethodValue.
	func TestNeedsInstance(t *testing.T) {
	const input = `
	package p

	import "unsafe"

	type Pointer[T any] struct {
	v unsafe.Pointer
	}

	func (x Pointer[T]) Load() T {
	return (*T)(LoadPointer(&x.v))
	}

	func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
	`
	// The SSA members for this package should look something like this:
	// func LoadPointer func(addr *unsafe.Pointer) (val unsafe.Pointer)
	// type Pointer struct{v unsafe.Pointer}
	// method (Pointer[T any]) Load() T
	// func init func()
	// var init$guard bool

	for _, mode := range []ssa.BuilderMode{
	ssa.SanityCheckFunctions,
	ssa.SanityCheckFunctions \| ssa.InstantiateGenerics,
	} {
	p, _ := buildPackage(t, input, mode)
	prog := p.Prog

	ptr := p.Type("Pointer").Type().(*types.Named)
	if ptr.NumMethods() != 1 {
	t.Fatalf("Expected Pointer to have 1 method. got %d", ptr.NumMethods())
	}

	obj := ptr.Method(0)
	if obj.Name() != "Load" {
	t.Errorf("Expected Pointer to have method named 'Load'. got %q", obj.Name())
	}

	meth := prog.FuncValue(obj)

	// instantiateLoadMethod returns the first method (Load) of the instantiation *Pointer[T].
	instantiateLoadMethod := func(T types.Type) *ssa.Function {
	ptrT, err := types.Instantiate(nil, ptr, []types.Type{T}, false)
	if err != nil {
	t.Fatalf("Failed to Instantiate %q by %q", ptr, T)
	}
	methods := types.NewMethodSet(types.NewPointer(ptrT))
	if methods.Len() != 1 {
	t.Fatalf("Expected 1 method for %q. got %d", ptrT, methods.Len())
	}
	return prog.MethodValue(methods.At(0))
	}

	intSliceTyp := types.NewSlice(types.Typ[types.Int])
	instance := instantiateLoadMethod(intSliceTyp) // (*Pointer[[]int]).Load
	if instance.Origin() != meth {
	t.Errorf("Expected Origin of %s to be %s. got %s", instance, meth, instance.Origin())
	}
	if len(instance.TypeArgs()) != 1 \|\| !types.Identical(instance.TypeArgs()[0], intSliceTyp) {
	t.Errorf("Expected TypeArgs of %s to be %v. got %v", instance, []types.Type{intSliceTyp}, instance.TypeArgs())
	}

	// A second request with an identical type returns the same Function.
	second := instantiateLoadMethod(types.NewSlice(types.Typ[types.Int]))
	if second != instance {
	t.Error("Expected second identical instantiation to be the same function")
	}

	// (*Pointer[[]uint]).Load
	inst2 := instantiateLoadMethod(types.NewSlice(types.Typ[types.Uint]))

	if instance.Name() >= inst2.Name() {
	t.Errorf("Expected name of instance %s to be before instance %v", instance, inst2)
	}
	}
	}

	// TestCallsToInstances checks that calles of calls to generic functions,
	// without monomorphization, are wrappers around the origin generic function.
	func TestCallsToInstances(t *testing.T) {
	const input = `
	package p

	type I interface {
	Foo()
	}

	type A int
	func (a A) Foo() {}

	type J[T any] interface{ Bar() T }
	type K[T any] struct{ J[T] }

	func Id[T any] (t T) T {
	return t
	}

	func Lambda[T I]() func() func(T) {
	return func() func(T) {
	return T.Foo
	}
	}

	func NoOp[T any]() {}

	func Bar[T interface { Foo(); ~int \| ~string }, U any] (t T, u U) {
	Id[U](u)
	Id[T](t)
	}

	func Make[T any]() interface{} {
	NoOp[K[T]]()
	return nil
	}

	func entry(i int, a A) int {
	Lambda[A]()()(a)

	x := Make[int]()
	if j, ok := x.(interface{ Bar() int }); ok {
	print(j)
	}

	Bar[A, int](a, i)

	return Id[int](i)
	}
	`
	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)
	all := ssautil.AllFunctions(p.Prog)

	for _, ti := range []struct {
	orig string
	instance string
	tparams string
	targs string
	chTypeInstrs int // number of ChangeType instructions in f's body
	}{
	{"Id", "Id[int]", "[T]", "[int]", 2},
	{"Lambda", "Lambda[p.A]", "[T]", "[p.A]", 1},
	{"Make", "Make[int]", "[T]", "[int]", 0},
	{"NoOp", "NoOp[p.K[T]]", "[T]", "[p.K[T]]", 0},
	} {
	test := ti
	t.Run(test.instance, func(t *testing.T) {
	f := p.Members[test.orig].(*ssa.Function)
	if f == nil {
	t.Fatalf("origin function not found")
	}

	var i *ssa.Function
	for _, fn := range instancesOf(all, f) {
	if fn.Name() == test.instance {
	i = fn
	break
	}
	}
	if i == nil {
	t.Fatalf("instance not found")
	}

	// for logging on failures
	var body strings.Builder
	i.WriteTo(&body)
	t.Log(body.String())

	if len(i.Blocks) != 1 {
	t.Fatalf("body has more than 1 block")
	}

	if instrs := changeTypeInstrs(i.Blocks[0]); instrs != test.chTypeInstrs {
	t.Errorf("want %v instructions; got %v", test.chTypeInstrs, instrs)
	}

	if test.tparams != tparams(i) {
	t.Errorf("want %v type params; got %v", test.tparams, tparams(i))
	}

	if test.targs != targs(i) {
	t.Errorf("want %v type arguments; got %v", test.targs, targs(i))
	}
	})
	}
	}

	func tparams(f *ssa.Function) string {
	tplist := f.TypeParams()
	var tps []string
	for i := 0; i < tplist.Len(); i++ {
	tps = append(tps, tplist.At(i).String())
	}
	return fmt.Sprint(tps)
	}

	func targs(f *ssa.Function) string {
	var tas []string
	for _, ta := range f.TypeArgs() {
	tas = append(tas, ta.String())
	}
	return fmt.Sprint(tas)
	}

	func changeTypeInstrs(b *ssa.BasicBlock) int {
	cnt := 0
	for _, i := range b.Instrs {
	if _, ok := i.(*ssa.ChangeType); ok {
	cnt++
	}
	}
	return cnt
	}

	func TestInstanceUniqueness(t *testing.T) {
	const input = `
	package p

	func H[T any](t T) {
	print(t)
	}

	func F[T any](t T) {
	H[T](t)
	H[T](t)
	H[T](t)
	}

	func G[T any](t T) {
	H[T](t)
	H[T](t)
	}

	func Foo[T any, S any](t T, s S) {
	Foo[S, T](s, t)
	Foo[T, S](t, s)
	}
	`
	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)

	all := ssautil.AllFunctions(p.Prog)
	for _, test := range []struct {
	orig string
	instances string
	}{
	{"H", "[p.H[T] p.H[T]]"},
	{"Foo", "[p.Foo[S T] p.Foo[T S]]"},
	} {
	t.Run(test.orig, func(t *testing.T) {
	f := p.Members[test.orig].(*ssa.Function)
	if f == nil {
	t.Fatalf("origin function not found")
	}

	instances := instancesOf(all, f)
	sort.Slice(instances, func(i, j int) bool { return instances[i].Name() < instances[j].Name() })

	if got := fmt.Sprintf("%v", instances); !reflect.DeepEqual(got, test.instances) {
	t.Errorf("got %v instances, want %v", got, test.instances)
	}
	})
	}
	}

	// instancesOf returns a new unordered slice of all instances of the
	// specified function g in fns.
	func instancesOf(fns map[ssa.Function]bool, g ssa.Function) []*ssa.Function {
	var instances []*ssa.Function
	for fn := range fns {
	if fn != g && fn.Origin() == g {
	instances = append(instances, fn)
	}
	}
	return instances
	}