go/callgraph/vta: add basic tests for range-over-func

The tests check the callees at the call to yield and type flow out of
the range-over-func iterator. If needed, a test for defer will be added
in a follow-up CL.

Change-Id: Ic9208ac0824a36fb50879730e8ec9398b9b6e284
Reviewed-on: https://go-review.googlesource.com/c/tools/+/611395
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Tim King <taking@google.com>

go/callgraph/vta/testdata/src/callgraph_range_over_func.go

@@ -0,0 +1,96 @@
+// 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.
+
+// go:build ignore
+
+package testdata
+
+type I interface {
+	Foo()
+}
+
+type A struct{}
+
+func (a A) Foo() {}
+
+type B struct{}
+
+func (b B) Foo() {}
+
+type C struct{}
+
+func (c C) Foo() {} // Test that this is not called.
+
+type iset []I
+
+func (i iset) All() func(func(I) bool) {
+	return func(yield func(I) bool) {
+		for _, v := range i {
+			if !yield(v) {
+				return
+			}
+		}
+	}
+}
+
+var x = iset([]I{A{}, B{}})
+
+func X() {
+	for i := range x.All() {
+		i.Foo()
+	}
+}
+
+func Y() I {
+	for i := range x.All() {
+		return i
+	}
+	return nil
+}
+
+func Bar() {
+	X()
+	y := Y()
+	y.Foo()
+}
+
+// Relevant SSA:
+//func X$1(I) bool:
+//	t0 = *jump$1
+//	t1 = t0 == 0:int
+//	if t1 goto 1 else 2
+//1:
+//	*jump$1 = -1:int
+//	t2 = invoke arg0.Foo()
+//	*jump$1 = 0:int
+//	return true:bool
+//2:
+//	t3 = make interface{} <- string ("yield function ca...":string) interface{}
+//	panic t3
+//
+//func All$1(yield func(I) bool):
+//	t0 = *i
+//	t1 = len(t0)
+//	jump 1
+//1:
+//	t2 = phi [0: -1:int, 2: t3] #rangeindex
+//	t3 = t2 + 1:int
+//	t4 = t3 < t1
+//	if t4 goto 2 else 3
+//2:
+//	t5 = &t0[t3]
+//	t6 = *t5
+//	t7 = yield(t6)
+//	if t7 goto 1 else 4
+//
+//func Bar():
+//	t0 = X()
+//	t1 = Y()
+//	t2 = invoke t1.Foo()
+//	return
+
+// WANT:
+// Bar: X() -> X; Y() -> Y; invoke t1.Foo() -> A.Foo, B.Foo
+// X$1: invoke arg0.Foo() -> A.Foo, B.Foo
+// All$1: yield(t6) -> X$1, Y$1

go/callgraph/vta/vta_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:debug gotypesalias=1
+
 package vta
 
 import (
@@ -15,7 +17,7 @@ import (
 	"golang.org/x/tools/go/callgraph/cha"
 	"golang.org/x/tools/go/ssa"
 	"golang.org/x/tools/go/ssa/ssautil"
-	"golang.org/x/tools/internal/aliases"
+	"golang.org/x/tools/internal/testenv"
 )
 
 func TestVTACallGraph(t *testing.T) {
@@ -27,7 +29,7 @@ func TestVTACallGraph(t *testing.T) {
 			cmp.Diff(got, want)) // to aid debugging
 	}
 
-	for _, file := range []string{
+	files := []string{
 		"testdata/src/callgraph_static.go",
 		"testdata/src/callgraph_ho.go",
 		"testdata/src/callgraph_interfaces.go",
@@ -38,14 +40,14 @@ func TestVTACallGraph(t *testing.T) {
 		"testdata/src/callgraph_recursive_types.go",
 		"testdata/src/callgraph_issue_57756.go",
 		"testdata/src/callgraph_comma_maps.go",
-		"testdata/src/callgraph_type_aliases.go",
-	} {
-		t.Run(file, func(t *testing.T) {
-			// https://github.com/golang/go/issues/68799
-			if !aliases.Enabled() && file == "testdata/src/callgraph_type_aliases.go" {
-				t.Skip("callgraph_type_aliases.go requires gotypesalias=1")
-			}
+		"testdata/src/callgraph_type_aliases.go", // https://github.com/golang/go/issues/68799
+	}
+	if testenv.Go1Point() >= 23 {
+		files = append(files, "testdata/src/callgraph_range_over_func.go")
+	}
 
+	for _, file := range files {
+		t.Run(file, func(t *testing.T) {
 			prog, want, err := testProg(file, ssa.BuilderMode(0))
 			if err != nil {
 				t.Fatalf("couldn't load test file '%s': %s", file, err)