code review 29500047: go.tools/go/types: Do not throw error on division of co...

go.tools/go/types: Do not throw error on division of complex variables by zero.

See http://play.golang.org/p/DrgLKnHaUW
Seems like division of a variable by zero should only throw an error if the variable is an integer.

[neelance, 2013-11-20 11:51:55]

Hello golang-dev@googlegroups.com (cc: gri@golang.org),

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

[mtj1, 2013-11-20 19:39:13]

The issue is between quiet and signalling NaNs


On Wed, Nov 20, 2013 at 3:51 AM, <Neelance@gmail.com> wrote:

> Reviewers: golang-dev1,
>
> Message:
> Hello golang-dev@googlegroups.com (cc: gri@golang.org),
>
> I'd like you to review this change to
> https://code.google.com/p/go.tools
>
>
> Description:
> go.tools/go/types: Do not throw error on division of complex variables
> by zero.
>
> See http://play.golang.org/p/DrgLKnHaUW
> Seems like division of a variable by zero should only throw an error if
> the variable is an integer.
>
> Please review this at https://codereview.appspot.com/29500047/
>
> Affected files (+2, -2 lines):
>   M go/types/expr.go
>   M go/types/testdata/stmt0.src
>
>
> Index: go/types/expr.go
> ===================================================================
> --- a/go/types/expr.go
> +++ b/go/types/expr.go
> @@ -762,7 +762,7 @@
>                 return
>         }
>
> -       if (op == token.QUO || op == token.REM) && (x.mode == constant ||
> !isFloat(x.typ)) && y.mode == constant && exact.Sign(y.val) == 0 {
> +       if (op == token.QUO || op == token.REM) && (x.mode == constant ||
> isInteger(x.typ)) && y.mode == constant && exact.Sign(y.val) == 0 {
>                 check.invalidOp(y.pos(), "division by zero")
>                 x.mode = invalid
>                 return
> Index: go/types/testdata/stmt0.src
> ===================================================================
> --- a/go/types/testdata/stmt0.src
> +++ b/go/types/testdata/stmt0.src
> @@ -57,7 +57,7 @@
>         f -= "foo" /* ERROR "cannot convert.*float64" */
>
>         c *= 1
> -       c /= 0 /* ERROR "division by zero" */
> +       c /= 0
>
>         s += "bar"
>         s += 1 /* ERROR "cannot convert.*string" */
>
>
> --
>
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-- 
Michael T. Jones | Chief Technology Advocate  | mtj@google.com |  +1
650-335-5765

[gri1, 2013-11-20 21:42:05]

LGTM

Yes: "If the divisor is a constant, it must not be zero." in
http://tip.golang.org/ref/spec#Arithmetic_operators . This only applies to
integers.

[gri, 2013-11-20 21:42:31]

*** Submitted as
https://code.google.com/p/go/source/detail?r=4cc1611bed2e&repo=tools ***

go.tools/go/types: Do not throw error on division of complex variables by zero.

See http://play.golang.org/p/DrgLKnHaUW
Seems like division of a variable by zero should only throw an error if the
variable is an integer.

R=golang-dev, mtj, gri
CC=golang-dev, gri
https://codereview.appspot.com/29500047

Committer: Robert Griesemer <gri@golang.org>