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cmd/compile/internal/types2: produce empty type set for invalid ~T
If ~T is not permitted because the underlying type of T is not the same as T, there is no type that satisfies ~T. Besides reporting an error, also ensure that the corresponding type set is empty. For #49739. Change-Id: I127f75f170902e7989f7fe7b352dabda9f72e2a5 Reviewed-on: https://go-review.googlesource.com/c/go/+/366278 Trust: Robert Griesemer <gri@golang.org> Reviewed-by: Robert Findley <rfindley@google.com>
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23
src/cmd/compile/internal/types2/testdata/fixedbugs/issue49739.go2
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src/cmd/compile/internal/types2/testdata/fixedbugs/issue49739.go2
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@ -0,0 +1,23 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Verify that we get an empty type set (not just an error)
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// when using an invalid ~A.
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package p
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type A int
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type C interface {
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~ /* ERROR invalid use of ~ */ A
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}
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func f[_ C]() {}
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func g[_ interface{ C }]() {}
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func h[_ C | int]() {}
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func _() {
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_ = f[int /* ERROR cannot implement C \(empty type set\) */]
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_ = g[int /* ERROR cannot implement interface{C} \(empty type set\) */]
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_ = h[int]
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}
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@ -367,14 +367,18 @@ func computeUnionTypeSet(check *Checker, pos syntax.Pos, utyp *Union) *_TypeSet
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var allTerms termlist
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var allTerms termlist
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for _, t := range utyp.terms {
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for _, t := range utyp.terms {
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var terms termlist
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var terms termlist
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switch u := under(t.typ).(type) {
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u := under(t.typ)
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case *Interface:
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if ui, _ := u.(*Interface); ui != nil {
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// For now we don't permit type parameters as constraints.
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// For now we don't permit type parameters as constraints.
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assert(!isTypeParam(t.typ))
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assert(!isTypeParam(t.typ))
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terms = computeInterfaceTypeSet(check, pos, u).terms
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terms = computeInterfaceTypeSet(check, pos, ui).terms
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default:
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} else if t.typ == Typ[Invalid] {
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if t.typ == Typ[Invalid] {
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continue
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continue
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} else {
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if t.tilde && !Identical(t.typ, u) {
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// There is no underlying type which is t.typ.
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// The corresponding type set is empty.
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t = nil // ∅ term
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}
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}
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terms = termlist{(*term)(t)}
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terms = termlist{(*term)(t)}
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}
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}
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