code review 3782044: simple fix to not have 'exp/eval' panic in presence of ...

simple fix to not have 'exp/eval' panic in presence of slices like s[:2]

[binet, 2010-12-27 17:11:31]

Hello golang-dev@googlegroups.com (cc: binet@cern.ch,
golang-dev@googlegroups.com),

I'd like you to review this change.

[gri, 2010-12-27 18:05:15]

LGTM
- gri

On Mon, Dec 27, 2010 at 9:11 AM, <seb.binet@gmail.com> wrote:

> Reviewers: golang-dev_googlegroups.com,
>
> Message:
> Hello golang-dev@googlegroups.com (cc: binet@cern.ch,
> golang-dev@googlegroups.com),
>
> I'd like you to review this change.
>
>
> Description:
> simple fix to not have 'exp/eval' panic in presence of slices like s[:2]
>
> Please review this at http://codereview.appspot.com/3782044/
>
> Affected files:
>  M src/pkg/exp/eval/expr.go
>
>
> Index: src/pkg/exp/eval/expr.go
> ===================================================================
> --- a/src/pkg/exp/eval/expr.go
> +++ b/src/pkg/exp/eval/expr.go
> @@ -595,9 +595,15 @@
>                return ei.compileIndexExpr(l, r)
>
>        case *ast.SliceExpr:
> -               var hi *expr
> +               var lo, hi *expr
>                arr := a.compile(x.X, false)
> -               lo := a.compile(x.Index, false)
> +               if x.Index == nil {
> +                       // beginning was omitted, so we need to provide it
> +                       ei := &exprInfo{a.compiler, x.Pos()}
> +                       lo = ei.compileIntLit("0")
> +               } else {
> +                       lo = a.compile(x.Index, false)
> +               }
>                if x.End == nil {
>                        // End was omitted, so we need to compute len(x.X)
>                        ei := &exprInfo{a.compiler, x.Pos()}
>
>
>

[gri, 2010-12-27 18:05:37]

*** Submitted as http://code.google.com/p/go/source/detail?r=81a710b53545 ***

simple fix to not have 'exp/eval' panic in presence of slices like s[:2]

R=golang-dev, gri
CC=binet, golang-dev
http://codereview.appspot.com/3782044

Committer: Robert Griesemer <gri@golang.org>