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go/types, types2: delay "does not satisfy comparable" error until needed

Fixes #49112.

Change-Id: I8effbca7bcbb257b18fd4d3d1914fd10d4afaaae
Reviewed-on: https://go-review.googlesource.com/c/go/+/372594
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-12-15 16:13:05 -08:00 committed by Robert Findley
parent 87b2a54827
commit a2004de088
8 changed files with 64 additions and 40 deletions

View File

@ -192,17 +192,7 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
return errorf("cannot implement %s (empty type set)", T)
}
// If T is comparable, V must be comparable.
// TODO(gri) the error messages could be better, here
if Ti.IsComparable() && !Comparable(V) {
if Vi != nil && Vi.Empty() {
return errorf("empty interface %s does not implement %s", V, T)
}
return errorf("%s does not implement comparable", V)
}
// V must implement T (methods)
// - check only if we have methods
// V must implement T's methods, if any.
if Ti.NumMethods() > 0 {
if m, wrong := check.missingMethod(V, Ti, true); m != nil {
// TODO(gri) needs to print updated name to avoid major confusion in error message!
@ -220,10 +210,17 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
}
}
// If T is comparable, V must be comparable.
// Remember as a pending error and report only if we don't have a more specific error.
var pending error
if Ti.IsComparable() && !Comparable(V) {
pending = errorf("%s does not implement comparable", V)
}
// V must also be in the set of types of T, if any.
// Constraints with empty type sets were already excluded above.
if !Ti.typeSet().hasTerms() {
return nil // nothing to do
return pending // nothing to do
}
// If V is itself an interface, each of its possible types must be in the set
@ -234,7 +231,7 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
// TODO(gri) report which type is missing
return errorf("%s does not implement %s", V, T)
}
return nil
return pending
}
// Otherwise, V's type must be included in the iface type set.
@ -262,5 +259,5 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
}
}
return nil
return pending
}

View File

@ -58,7 +58,7 @@ func _() {
type T1[P interface{~uint}] struct{}
func _[P any]() {
_ = T1[P /* ERROR empty interface P does not implement interface{~uint} */ ]{}
_ = T1[P /* ERROR P does not implement interface{~uint} */ ]{}
}
// This is the original (simplified) program causing the same issue.
@ -74,8 +74,8 @@ func (u T2[U]) Add1() U {
return u.s + 1
}
func NewT2[U any]() T2[U /* ERROR empty interface U does not implement Unsigned */ ] {
return T2[U /* ERROR empty interface U does not implement Unsigned */ ]{}
func NewT2[U any]() T2[U /* ERROR U does not implement Unsigned */ ] {
return T2[U /* ERROR U does not implement Unsigned */ ]{}
}
func _() {

View File

@ -16,11 +16,11 @@ func _[P comparable,
_ = f[P]
_ = f[Q]
_ = f[func( /* ERROR does not implement comparable */ )]
_ = f[R /* ERROR empty interface R does not implement comparable */ ]
_ = f[R /* ERROR R does not implement comparable */ ]
_ = g[int]
_ = g[P /* ERROR P does not implement interface{interface{comparable; ~int\|~string} */ ]
_ = g[Q]
_ = g[func( /* ERROR does not implement comparable */ )]
_ = g[R /* ERROR empty interface R does not implement interface{interface{comparable; ~int\|~string} */ ]
_ = g[func( /* ERROR func\(\) does not implement interface{interface{comparable; ~int\|~string}} */ )]
_ = g[R /* ERROR R does not implement interface{interface{comparable; ~int\|~string} */ ]
}

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@ -0,0 +1,15 @@
// Copyright 2021 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
func f[P int](P) {}
func _() {
_ = f[int]
_ = f[[ /* ERROR \[\]int does not implement int */ ]int]
f(0)
f( /* ERROR \[\]int does not implement int */ []int{})
}

View File

@ -192,17 +192,7 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
return errorf("cannot implement %s (empty type set)", T)
}
// If T is comparable, V must be comparable.
// TODO(gri) the error messages could be better, here
if Ti.IsComparable() && !Comparable(V) {
if Vi != nil && Vi.Empty() {
return errorf("empty interface %s does not implement %s", V, T)
}
return errorf("%s does not implement comparable", V)
}
// V must implement T (methods)
// - check only if we have methods
// V must implement T's methods, if any.
if Ti.NumMethods() > 0 {
if m, wrong := check.missingMethod(V, Ti, true); m != nil {
// TODO(gri) needs to print updated name to avoid major confusion in error message!
@ -221,10 +211,17 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
}
}
// If T is comparable, V must be comparable.
// Remember as a pending error and report only if we don't have a more specific error.
var pending error
if Ti.IsComparable() && !Comparable(V) {
pending = errorf("%s does not implement comparable", V)
}
// V must also be in the set of types of T, if any.
// Constraints with empty type sets were already excluded above.
if !Ti.typeSet().hasTerms() {
return nil // nothing to do
return pending // nothing to do
}
// If V is itself an interface, each of its possible types must be in the set
@ -235,7 +232,7 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
// TODO(gri) report which type is missing
return errorf("%s does not implement %s", V, T)
}
return nil
return pending
}
// Otherwise, V's type must be included in the iface type set.
@ -263,5 +260,5 @@ func (check *Checker) implements(V, T Type, qf Qualifier) error {
}
}
return nil
return pending
}

View File

@ -58,7 +58,7 @@ func _() {
type T1[P interface{~uint}] struct{}
func _[P any]() {
_ = T1[P /* ERROR empty interface P does not implement interface{~uint} */ ]{}
_ = T1[P /* ERROR P does not implement interface{~uint} */ ]{}
}
// This is the original (simplified) program causing the same issue.
@ -74,8 +74,8 @@ func (u T2[U]) Add1() U {
return u.s + 1
}
func NewT2[U any]() T2[U /* ERROR empty interface U does not implement Unsigned */ ] {
return T2[U /* ERROR empty interface U does not implement Unsigned */ ]{}
func NewT2[U any]() T2[U /* ERROR U does not implement Unsigned */ ] {
return T2[U /* ERROR U does not implement Unsigned */ ]{}
}
func _() {

View File

@ -16,11 +16,11 @@ func _[P comparable,
_ = f[P]
_ = f[Q]
_ = f[func /* ERROR does not implement comparable */ ()]
_ = f[R /* ERROR empty interface R does not implement comparable */ ]
_ = f[R /* ERROR R does not implement comparable */ ]
_ = g[int]
_ = g[P /* ERROR P does not implement interface{interface{comparable; ~int\|~string} */ ]
_ = g[Q]
_ = g[func /* ERROR does not implement comparable */ ()]
_ = g[R /* ERROR empty interface R does not implement interface{interface{comparable; ~int\|~string} */ ]
_ = g[func /* ERROR func\(\) does not implement interface{interface{comparable; ~int\|~string}} */ ()]
_ = g[R /* ERROR R does not implement interface{interface{comparable; ~int\|~string} */ ]
}

View File

@ -0,0 +1,15 @@
// Copyright 2021 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
func f[P int](P) {}
func _() {
_ = f[int]
_ = f[[ /* ERROR \[\]int does not implement int */ ]int]
f(0)
f/* ERROR \[\]int does not implement int */ ([]int{})
}