cmd/compile: bug in global variable initialization #29013
Description
package main
import "fmt"
type TestSuite struct {
Tests []Test
}
type Test struct {
Want interface{}
}
type Int struct {
i int
}
func NewInt(v int) Int {
return Int{i: v}
}
var Suites = []TestSuite{
Dicts,
}
var Dicts = TestSuite{
Tests: []Test{
{
Want: map[Int]bool{NewInt(1): true},
},
{
Want: map[Int]string{
NewInt(3): "3",
},
},
},
}
func main() {
var mym = Dicts.Tests[0].Want.(map[Int]bool)
fmt.Printf("%p %p %v\n", &Dicts.Tests[0], mym, mym)
var mym2 = Suites[0].Tests[0].Want.(map[Int]bool)
fmt.Printf("%p %p %v\n", &Suites[0].Tests[0], mym2, mym2)
}
When I run this on tip, I get:
0x54d580 0xc00007c150 map[{1}:true]
0x54d5a0 0xc00007c1b0 map[{3}:true]
That's clearly not right. Where did the map[3]=true come from?
On 1.11, I get:
0x548640 0xc000082150 map[{1}:true]
0x548660 0xc0000821b0 map[{1}:true]
Which is more correct. But not actually completely correct. I think we should have &Suites[0].Tests[0] == &Dicts.Tests[0], but we don't. This may or may not be related to the first bug.
This started happening after my reuse temporaries change: https://go-review.googlesource.com/c/go/+/140301 I'm not sure yet if that CL is actually buggy or just triggered something underlying.