[dev.typealias] cmd/compile: avoid false positive cycles from type aliases

For #18130.
Fixes #18640.

Change-Id: I26cf1d1b78cca6ef207cc4333f30a9011ef347c9
Reviewed-on: https://go-review.googlesource.com/35831
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Matthew Dempsky 2017-01-26 09:00:56 -08:00
parent 49b7af8a30
commit 9ecc3ee252
2 changed files with 30 additions and 2 deletions

View file

@ -339,13 +339,15 @@ func Main() {
// Phase 1: const, type, and names and types of funcs.
// This will gather all the information about types
// and methods but doesn't depend on any of it.
// We also defer type alias declarations until phase 2
// to avoid cycles like #18640.
defercheckwidth()
// Don't use range--typecheck can add closures to xtop.
timings.Start("fe", "typecheck", "top1")
for i := 0; i < len(xtop); i++ {
n := xtop[i]
if op := n.Op; op != ODCL && op != OAS && op != OAS2 {
if op := n.Op; op != ODCL && op != OAS && op != OAS2 && (op != ODCLTYPE || !n.Left.Name.Param.Alias) {
xtop[i] = typecheck(n, Etop)
}
}
@ -357,7 +359,7 @@ func Main() {
timings.Start("fe", "typecheck", "top2")
for i := 0; i < len(xtop); i++ {
n := xtop[i]
if op := n.Op; op == ODCL || op == OAS || op == OAS2 {
if op := n.Op; op == ODCL || op == OAS || op == OAS2 || op == ODCLTYPE && n.Left.Name.Param.Alias {
xtop[i] = typecheck(n, Etop)
}
}

View file

@ -0,0 +1,26 @@
// compile
// Copyright 2017 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 (
a = b
b struct {
*a
}
c struct {
*d
}
d = c
e = f
f = g
g = []h
h i
i = j
j = e
)