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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
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@ -621,10 +621,23 @@ func checkDupExprCases(exprname *Node, clauses []*Node) {
}
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 {
typ string
typ *types.Type
val interface{}
}
seen := make(map[typeVal]*Node)
@ -634,9 +647,15 @@ func checkDupExprCases(exprname *Node, clauses []*Node) {
continue
}
tv := typeVal{
typ: n.Type.LongString(),
typ: n.Type,
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]
if !dup {
seen[tv] = n