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[dev.typeparams] cmd/compile/internal/types2: interface identity must consider full type set

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There is no (obvious) way to test this at the moment because we
don't permit such constraint interfaces as ordinary types.

Change-Id: Ieeec023ed82a2c71ed50d111f26916aba4a59099
Reviewed-on: https://go-review.googlesource.com/c/go/+/333889
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-07-11 15:27:49 -07:00
parent 2a8087817c
commit dd8bdf4a1f
2 changed files with 21 additions and 8 deletions
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17
src/cmd/compile/internal/types2/predicates.go
View File

@ -270,12 +270,21 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
}
case *Interface:
// Two interface types are identical if they describe the same type sets.
// With the existing implementation restriction, this simplifies to:
//
// Two interface types are identical if they have the same set of methods with
// the same names and identical function types. Lower-case method names from
// different packages are always different. The order of the methods is irrelevant.
// the same names and identical function types, and if any type restrictions
// are the same. Lower-case method names from different packages are always
// different. The order of the methods is irrelevant.
if y, ok := y.(*Interface); ok {
a := x.typeSet().methods
b := y.typeSet().methods
xset := x.typeSet()
yset := y.typeSet()
if !Identical(xset.types, yset.types) {
return false
}
a := xset.methods
b := yset.methods
if len(a) == len(b) {
// Interface types are the only types where cycles can occur
// that are not "terminated" via named types; and such cycles

12
src/cmd/compile/internal/types2/unify.go
View File

@ -362,16 +362,20 @@ func (u *unifier) nify(x, y Type, p *ifacePair) bool {
}
case *Union:
// This should not happen with the current internal use of union types.
panic("type inference across union types not implemented")
panic("unimplemented: unification with type sets described by types")
case *Interface:
// Two interface types are identical if they have the same set of methods with
// the same names and identical function types. Lower-case method names from
// different packages are always different. The order of the methods is irrelevant.
if y, ok := y.(*Interface); ok {
a := x.typeSet().methods
b := y.typeSet().methods
xset := x.typeSet()
yset := y.typeSet()
if !Identical(xset.types, yset.types) {
return false
}
a := xset.methods
b := yset.methods
if len(a) == len(b) {
// Interface types are the only types where cycles can occur
// that are not "terminated" via named types; and such cycles