| 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 | type I interface { |
| 10 | Foo() |
| 11 | } |
| 12 | |
| 13 | type A struct { |
| 14 | f *I |
| 15 | } |
| 16 | |
| 17 | func (a A) Foo() {} |
| 18 | |
| 19 | type B struct{} |
| 20 | |
| 21 | func (b B) Foo() {} |
| 22 | |
| 23 | func Do(a A, i I, c bool) *I { |
| 24 | if c { |
| 25 | *a.f = a |
| 26 | } else { |
| 27 | a.f = &i |
| 28 | } |
| 29 | (*a.f).Foo() |
| 30 | return &i |
| 31 | } |
| 32 | |
| 33 | func Baz(a A, b B, c bool) { |
| 34 | x := Do(a, b, c) |
| 35 | (*x).Foo() |
| 36 | } |
| 37 | |
| 38 | // Relevant SSA: |
| 39 | // func Baz(a A, b B, c bool): |
| 40 | // t0 = local A (a) |
| 41 | // ... |
| 42 | // t5 = Do(t2, t4, c) |
| 43 | // t6 = *t5 |
| 44 | // t7 = invoke t6.Foo() |
| 45 | // return |
| 46 | |
| 47 | // func Do(a A, i I, c bool) *I: |
| 48 | // t0 = local A (a) |
| 49 | // *t0 = a |
| 50 | // ... |
| 51 | // if c goto 1 else 3 |
| 52 | // 1: |
| 53 | // t2 = &t0.f [#0] |
| 54 | // ... |
| 55 | // jump 2 |
| 56 | // 2: |
| 57 | // t6 = &t0.f [#0] |
| 58 | // ... |
| 59 | // t9 = invoke t8.Foo() |
| 60 | // return t1 |
| 61 | // 3: |
| 62 | // t10 = &t0.f [#0] alias between A.f and t10 |
| 63 | // *t10 = t1 alias between t10 and t1 |
| 64 | // jump 2 |
| 65 | |
| 66 | // The command a.f = &i introduces aliasing that results in |
| 67 | // A and B reaching both *A.f and return value of Do(a, b, c). |
| 68 | |
| 69 | // WANT: |
| 70 | // Baz: Do(t2, t4, c) -> Do; invoke t6.Foo() -> A.Foo, B.Foo |
| 71 | // Do: invoke t8.Foo() -> A.Foo, B.Foo |
| 72 |