go/callgraph/vta: add type alias test

Change-Id: Id3b3157d916a63e82a48fba066ac8bab56c21c98
Reviewed-on: https://go-review.googlesource.com/c/tools/+/579256
Run-TryBot: Zvonimir Pavlinovic <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Tim King <[email protected]>

Author: zpavlinovic

go/callgraph/vta/testdata/src/callgraph_type_aliases.go

@@ -0,0 +1,67 @@
+// 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
+
+// This file is the same as callgraph_interfaces.go except for
+// types J, X, Y, and Z aliasing types I, A, B, and C, resp.
+
+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() {}
+
+type J = I
+type X = A
+type Y = B
+type Z = C
+
+func NewY() Y {
+	return Y{}
+}
+
+func Do(b bool) J {
+	if b {
+		return X{}
+	}
+
+	z := Z{}
+	z.Foo()
+
+	return NewY()
+}
+
+func Baz(b bool) {
+	Do(b).Foo()
+}
+
+// Relevant SSA:
+// func Baz(b bool):
+//   t0 = Do(b)
+//   t1 = invoke t0.Foo()
+//   return
+
+// func Do(b bool) I:
+//    ...
+//   t1 = (C).Foo(struct{}{}:C)
+//   t2 = NewY()
+//   t3 = make I <- B (t2)
+//   return t3
+
+// WANT:
+// Baz: Do(b) -> Do; invoke t0.Foo() -> A.Foo, B.Foo
+// Do: (C).Foo(struct{}{}:C) -> C.Foo; NewY() -> NewY

go/callgraph/vta/vta_test.go

@@ -27,6 +27,7 @@ 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) {
 			prog, want, err := testProg(file, ssa.BuilderMode(0))
@@ -40,7 +41,7 @@ func TestVTACallGraph(t *testing.T) {
 			g := CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
 			got := callGraphStr(g)
 			if diff := setdiff(want, got); len(diff) > 0 {
-				t.Errorf("computed callgraph %v should contain %v (diff: %v)", got, want, diff)
+				t.Errorf("computed callgraph %v\nshould contain\n%v\n(diff: %v)", got, want, diff)
 			}
 		})
 	}