code review 141700043: fmt: fix allocation tests

fmt: fix allocation tests

Converting an integer to an interface{} allocates as of CL 130240043.

Fixes issue 8617.

[josharian, 2014-09-18 16:43:55]

Hello r@golang.org (cc: golang-codereviews@googlegroups.com, khr@golang.org),

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

[r, 2014-09-18 16:44:39]

LGTM
yup
sigh

[josharian, 2014-09-18 16:45:11]

*** Submitted as https://code.google.com/p/go/source/detail?r=0316cda6569c ***

fmt: fix allocation tests

Converting an integer to an interface{} allocates as of CL 130240043.

Fixes issue 8617.

LGTM=r
R=r
CC=golang-codereviews, khr
https://codereview.appspot.com/141700043

[iant, 2014-09-18 18:36:23]

In principle escape analysis should be able to detect that the allocation is not
necessary.  If an interface argument does not escape, then we can use a stack
pointer for the value stored in the interface.  In this case we have a
[]interface{}, so we need to know both that the slice as a whole does not escape
and that none of the elements of the slice escape.