code review 88360043: cmd/gc: fix segfault in isgoconst.

cmd/gc: fix segfault in isgoconst.
Not all literal nodes have sym->def.
Fixes issue 7794.

[minux1, 2014-04-16 04:51:26]

Hello golang-codereviews@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go

[bradfitz, 2014-04-16 15:22:50]

R=rsc



On Tue, Apr 15, 2014 at 9:51 PM, <minux.ma@gmail.com> wrote:

> Reviewers: golang-codereviews,
>
> Message:
> Hello golang-codereviews@googlegroups.com,
>
> I'd like you to review this change to
> https://code.google.com/p/go
>
>
> Description:
> cmd/gc: fix segfault in isgoconst.
> Not all literal nodes have sym->def.
> Fixes issue 7794.
>
> Please review this at https://codereview.appspot.com/88360043/
>
> Affected files (+13, -1 lines):
>   M src/cmd/gc/const.c
>   A test/fixedbugs/issue7794.go
>
>
> Index: src/cmd/gc/const.c
> ===================================================================
> --- a/src/cmd/gc/const.c
> +++ b/src/cmd/gc/const.c
> @@ -1594,7 +1594,7 @@
>
>         case ONAME:
>                 l = n->sym->def;
> -               if(l->op == OLITERAL && n->val.ctype != CTNIL)
> +               if(l && l->op == OLITERAL && n->val.ctype != CTNIL)
>                         return 1;
>                 break;
>
> Index: test/fixedbugs/issue7794.go
> ===================================================================
> new file mode 100644
> --- /dev/null
> +++ b/test/fixedbugs/issue7794.go
> @@ -0,0 +1,12 @@
> +// compile
> +
> +// Copyright 2014 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 main
> +
> +func main() {
> +       var a [10]int
> +       const ca = len(a)
> +}
>
>
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[rsc, 2014-04-16 15:37:32]

LGTM

It's not the literal node that's missing the def; it seems to be the 'var a
[10]int' that is missing the def. Is that correct?

[rsc, 2014-04-17 03:11:56]

I confirmed this and will update the CL description while submitting.

[rsc, 2014-04-17 03:12:11]

*** Submitted as https://code.google.com/p/go/source/detail?r=b60e0f4c348e ***

cmd/gc: fix segfault in isgoconst.

Variables declared with 'var' have no sym->def.

Fixes issue 7794.

LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://codereview.appspot.com/88360043

Committer: Russ Cox <rsc@golang.org>