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cmd/compile: prevent detection of wrong duplicates

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by including *types.Type in typeVal.

Updates #21866
Fixes #24159

Change-Id: I2f8cac252d88d43e723124f2867b1410b7abab7b
Reviewed-on: https://go-review.googlesource.com/98476
Run-TryBot: Kunpei Sakai <namusyaka@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Kunpei Sakai 2018-03-04 06:14:42 +09:00 • committed by Matthew Dempsky
parent 2c0c68d621
commit b75e8a2a3b
2 changed files with 43 additions and 4 deletions
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27
src/cmd/compile/internal/gc/swt.go
View file

@ -621,10 +621,23 @@ func checkDupExprCases(exprname *Node, clauses []*Node) {
} }
return return
} }
// s's expression is an interface. This is fairly rare, so keep this simple.
// Duplicates are only duplicates if they have the same type and the same value. // s's expression is an interface. This is fairly rare, so
// keep this simple. Case expressions are only duplicates if
// they have the same value and identical types.
//
// In general, we have to use eqtype to test type identity,
// because == gives false negatives for anonymous types and
// the byte/uint8 and rune/int32 builtin type aliases.
// However, this is not a problem here, because constant
// expressions are always untyped or have a named type, and we
// explicitly handle the builtin type aliases below.
//
// This approach may need to be revisited though if we fix
// #21866 by treating all type aliases like byte/uint8 and
// rune/int32.
type typeVal struct { type typeVal struct {
typ string typ *types.Type
val interface{} val interface{}
} }
seen := make(map[typeVal]*Node) seen := make(map[typeVal]*Node)
@ -634,9 +647,15 @@ func checkDupExprCases(exprname *Node, clauses []*Node) {
continue continue
} }
tv := typeVal{ tv := typeVal{
typ: n.Type.LongString(), typ: n.Type,
val: n.Val().Interface(), val: n.Val().Interface(),
} }
switch tv.typ {
case types.Bytetype:
tv.typ = types.Types[TUINT8]
case types.Runetype:
tv.typ = types.Types[TINT32]
}
prev, dup := seen[tv] prev, dup := seen[tv]
if !dup { if !dup {
seen[tv] = n seen[tv] = n

20
test/fixedbugs/issue24159.go Normal file
View file

@ -0,0 +1,20 @@
// errorcheck
// Copyright 2018 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 intAlias = int
func f() {
switch interface{}(nil) {
case uint8(0):
case byte(0): // ERROR "duplicate case"
case int32(0):
case rune(0): // ERROR "duplicate case"
case int(0):
case intAlias(0): // ERROR "duplicate case"
}
}