code review 173890043: cmd/gc: omit non-explicit capacity in errors with map/c...

cmd/gc: omit non-explicit capacity in errors with map/chan make

Fixes issue 9083.

[cmang, 2014-11-10 19:43:39]

Hello rsc@golang.org (cc: bradfitz@golang.org,
golang-codereviews@googlegroups.com),

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

[rsc, 2014-11-10 19:47:20]

that works? i'm a little surprised that isideal somehow distinguishes
implicit from explicit.
it doesn't for slices; why does it for maps and chans?

[rsc, 2014-11-10 19:47:21]

that works? i'm a little surprised that isideal somehow distinguishes
implicit from explicit.
it doesn't for slices; why does it for maps and chans?

[rsc, 2014-11-10 19:47:37]

there should also be a test.

[cmang, 2014-11-10 20:27:26]

On 2014/11/10 19:47:20, rsc wrote:
> that works? i'm a little surprised that isideal somehow distinguishes
> implicit from explicit.
> it doesn't for slices; why does it for maps and chans?

isideal can distinguish because the constant 0 is made using nodintconst(0) when
typechecking maps and channels. nodintconst makes a literal node with an ideal
type, whereas using the numeric literal '0' or even an untyped constant integer
will use defaultlit and give it type TINT. This doesn't matter for slices,
because make(T) is not a valid syntax for slices.

[cmang, 2014-11-10 20:56:37]

On 2014/11/10 19:47:37, rsc wrote:
> there should also be a test.

Added a test case, PTAL.

[gobot, 2014-12-19 05:16:03]

R=close

To the author of this CL:

The Go project has moved to Gerrit Code Review.

If this CL should be continued, please see the latest version of
https://golang.org/doc/contribute.html for instructions on
how to set up Git and the Go project's Gerrit codereview plugin,
and then create a new change with your current code.

If there has been discussion on this CL, please give a link to it
(golang.org/cl/173890043 is best) in the description in your
new CL.

Thanks very much.