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cmd/compile: support generic alias type

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Type parameters on aliases are now allowed after #46477 accepted.

Updates #46477
Fixes #68054

Change-Id: Ic2e3b6f960a898163f47666e3a6bfe43b8cc22e2
Reviewed-on: https://go-review.googlesource.com/c/go/+/593715
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Robert Griesemer <gri@google.com>
This commit is contained in:
Cuong Manh Le 2024-06-20 22:58:24 +07:00 committed by Gopher Robot
parent 4f77a83589
commit 477ad7dd51
2 changed files with 35 additions and 1 deletions
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13
src/cmd/compile/internal/noder/writer.go
View File

@ -543,7 +543,7 @@ func (pw *pkgWriter) typIdx(typ types2.Type, dict *writerDict) typeInfo {
case *types2.Alias:
w.Code(pkgbits.TypeNamed)
w.namedType(typ.Obj(), nil)
w.namedType(splitAlias(typ))
case *types2.TypeParam:
w.derived = true
@ -2958,6 +2958,9 @@ func objTypeParams(obj types2.Object) *types2.TypeParamList {
if !obj.IsAlias() {
return obj.Type().(*types2.Named).TypeParams()
}
if alias, ok := obj.Type().(*types2.Alias); ok {
return alias.TypeParams()
}
}
return nil
}
@ -2974,6 +2977,14 @@ func splitNamed(typ *types2.Named) (*types2.TypeName, *types2.TypeList) {
return typ.Obj(), typ.TypeArgs()
}
// splitAlias is like splitNamed, but for an alias type.
func splitAlias(typ *types2.Alias) (*types2.TypeName, *types2.TypeList) {
orig := typ.Origin()
base.Assertf(typ.Obj() == orig.Obj(), "alias type %v has object %v, but %v has object %v", typ, typ.Obj(), orig, orig.Obj())
return typ.Obj(), typ.TypeArgs()
}
func asPragmaFlag(p syntax.Pragma) ir.PragmaFlag {
if p == nil {
return 0

23
test/fixedbugs/issue68054.go Normal file
View File

@ -0,0 +1,23 @@
// compile -goexperiment aliastypeparams
// 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.
package p
type Seq[V any] = func(yield func(V) bool)
func f[E any](seq Seq[E]) {
return
}
func g() {
f(Seq[int](nil))
}
type T[P any] struct{}
type A[P any] = T[P]
var _ A[int]