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go/types, types2: better error message for invalid == on type parameters

Fixes #48712.

Change-Id: I6f214cdfdd1815493f2a04828e8f0097f1d8c124
Reviewed-on: https://go-review.googlesource.com/c/go/+/372734
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 21:25:50 -08:00
parent 90860e0c31
commit 2639f2f79b
4 changed files with 110 additions and 8 deletions

View File

@ -770,10 +770,12 @@ func (check *Checker) comparison(x, y *operand, op syntax.Operator) {
xok, _ := x.assignableTo(check, y.typ, nil)
yok, _ := y.assignableTo(check, x.typ, nil)
if xok || yok {
equality := false
defined := false
switch op {
case syntax.Eql, syntax.Neq:
// spec: "The equality operators == and != apply to operands that are comparable."
equality = true
defined = Comparable(x.typ) && Comparable(y.typ) || x.isNil() && hasNil(y.typ) || y.isNil() && hasNil(x.typ)
case syntax.Lss, syntax.Leq, syntax.Gtr, syntax.Geq:
// spec: The ordering operators <, <=, >, and >= apply to operands that are ordered."
@ -782,11 +784,19 @@ func (check *Checker) comparison(x, y *operand, op syntax.Operator) {
unreachable()
}
if !defined {
typ := x.typ
if x.isNil() {
typ = y.typ
if equality && (isTypeParam(x.typ) || isTypeParam(y.typ)) {
typ := x.typ
if isTypeParam(y.typ) {
typ = y.typ
}
err = check.sprintf("%s is not comparable", typ)
} else {
typ := x.typ
if x.isNil() {
typ = y.typ
}
err = check.sprintf("operator %s not defined on %s", op, typ)
}
err = check.sprintf("operator %s not defined on %s", op, typ)
}
} else {
err = check.sprintf("mismatched types %s and %s", x.typ, y.typ)

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@ -0,0 +1,41 @@
// Copyright 2022 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 _[P comparable](x, y P) {
_ = x == x
_ = x == y
_ = y == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P comparable](x P, y any) {
_ = x == x
_ = x == y
_ = y == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P any](x, y P) {
_ = x /* ERROR P is not comparable */ == x
_ = x /* ERROR P is not comparable */ == y
_ = y /* ERROR P is not comparable */ == x
_ = y /* ERROR P is not comparable */ == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P any](x P, y any) {
_ = x /* ERROR P is not comparable */ == x
_ = x /* ERROR P is not comparable */ == y
_ = y /* ERROR P is not comparable */ == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}

View File

@ -729,10 +729,12 @@ func (check *Checker) comparison(x, y *operand, op token.Token) {
xok, _ := x.assignableTo(check, y.typ, nil)
yok, _ := y.assignableTo(check, x.typ, nil)
if xok || yok {
equality := false
defined := false
switch op {
case token.EQL, token.NEQ:
// spec: "The equality operators == and != apply to operands that are comparable."
equality = true
defined = Comparable(x.typ) && Comparable(y.typ) || x.isNil() && hasNil(y.typ) || y.isNil() && hasNil(x.typ)
case token.LSS, token.LEQ, token.GTR, token.GEQ:
// spec: The ordering operators <, <=, >, and >= apply to operands that are ordered."
@ -741,11 +743,19 @@ func (check *Checker) comparison(x, y *operand, op token.Token) {
unreachable()
}
if !defined {
typ := x.typ
if x.isNil() {
typ = y.typ
if equality && (isTypeParam(x.typ) || isTypeParam(y.typ)) {
typ := x.typ
if isTypeParam(y.typ) {
typ = y.typ
}
err = check.sprintf("%s is not comparable", typ)
} else {
typ := x.typ
if x.isNil() {
typ = y.typ
}
err = check.sprintf("operator %s not defined on %s", op, typ)
}
err = check.sprintf("operator %s not defined on %s", op, typ)
code = _UndefinedOp
}
} else {

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@ -0,0 +1,41 @@
// Copyright 2022 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 _[P comparable](x, y P) {
_ = x == x
_ = x == y
_ = y == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P comparable](x P, y any) {
_ = x == x
_ = x == y
_ = y == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P any](x, y P) {
_ = x /* ERROR P is not comparable */ == x
_ = x /* ERROR P is not comparable */ == y
_ = y /* ERROR P is not comparable */ == x
_ = y /* ERROR P is not comparable */ == y
_ = x /* ERROR operator < not defined on P */ < y
}
func _[P any](x P, y any) {
_ = x /* ERROR P is not comparable */ == x
_ = x /* ERROR P is not comparable */ == y
_ = y /* ERROR P is not comparable */ == x
_ = y == y
_ = x /* ERROR operator < not defined on P */ < y
}