| 1 | // Copyright 2021 The Go Authors. All rights reserved. |
|---|---|
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | // go:build ignore |
| 6 | |
| 7 | package testdata |
| 8 | |
| 9 | // TestNodeTypeUniqueness checks if semantically equivalent types |
| 10 | // are being represented using the same pointer value in vta nodes. |
| 11 | // If not, some edges become missing in the string representation |
| 12 | // of the graph. |
| 13 | |
| 14 | type I interface { |
| 15 | Foo() |
| 16 | } |
| 17 | |
| 18 | type A struct{} |
| 19 | |
| 20 | func (a A) Foo() {} |
| 21 | |
| 22 | func Baz(a *A) (I, I, interface{}, interface{}) { |
| 23 | var i I |
| 24 | i = a |
| 25 | |
| 26 | var ii I |
| 27 | aa := &A{} |
| 28 | ii = aa |
| 29 | |
| 30 | m := make(map[int]int) |
| 31 | var iii interface{} |
| 32 | iii = m |
| 33 | |
| 34 | var iiii interface{} |
| 35 | iiii = m |
| 36 | |
| 37 | return i, ii, iii, iiii |
| 38 | } |
| 39 | |
| 40 | // Relevant SSA: |
| 41 | // func Baz(a *A) (I, I, interface{}, interface{}): |
| 42 | // t0 = make I <- *A (a) |
| 43 | // t1 = new A (complit) |
| 44 | // t2 = make I <- *A (t1) |
| 45 | // t3 = make map[int]int |
| 46 | // t4 = make interface{} <- map[int]int (t3) |
| 47 | // t5 = make interface{} <- map[int]int (t3) |
| 48 | // return t0, t2, t4, t5 |
| 49 | |
| 50 | // Without canon approach, one of Pointer(*A) -> Local(t0) and Pointer(*A) -> Local(t2) edges is |
| 51 | // missing in the graph string representation. The original graph has both of the edges but the |
| 52 | // source node Pointer(*A) is not the same; two occurrences of Pointer(*A) are considered separate |
| 53 | // nodes. Since they have the same string representation, one edge gets overridden by the other |
| 54 | // during the graph stringification, instead of being joined together as in below. |
| 55 | |
| 56 | // WANT: |
| 57 | // Pointer(*testdata.A) -> Local(t0), Local(t2) |
| 58 | // Local(t3) -> Local(t4), Local(t5) |
| 59 |