code review 7142052: cmd/gc: don't hash nor compare struct padding or blank ...

cmd/gc: don't hash nor compare struct padding or blank fields.

Fixes issue 4585.

[remyoudompheng, 2013-01-18 10:41:23]

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

I'd like you to review this change to
https://go.googlecode.com/hg/

[remyoudompheng, 2013-01-18 10:43:13]

https://codereview.appspot.com/7142052/diff/3/test/blank.go
File test/blank.go (right):

https://codereview.appspot.com/7142052/diff/3/test/blank.go#newcode108
test/blank.go:108: }
this test used to trigger a compilation error:

./blank.go:106: ambiguous selector autotmp_0012._
./blank.go:106: ambiguous selector autotmp_0013._
./blank.go:106: ambiguous selector autotmp_0012._
./blank.go:106: ambiguous selector autotmp_0013._
./blank.go:106: ambiguous selector autotmp_0012._
./blank.go:106: ambiguous selector autotmp_0013._

[rsc, 2013-01-18 16:42:28]

LGTM

Thanks very much for fixing this.

https://codereview.appspot.com/7142052/diff/3/test/blank.go
File test/blank.go (right):

https://codereview.appspot.com/7142052/diff/3/test/blank.go#newcode109
test/blank.go:109: 
The T struct above may be zeroed in some implementations. Could you please force
the memory to be different, like:

type T1 struct { x, y, z int }

*(*T1)(unsafe.Pointer(&t1)) = T1{1,2,3}
*(*T1)(unsafe.Pointer(&t1)) = T1{4,5,6}
if t1 != t2 {
    panic("T{} != T{}")
}

[remyoudompheng, 2013-01-18 17:26:56]

*** Submitted as https://code.google.com/p/go/source/detail?r=7059eeacbfba ***

cmd/gc: don't hash nor compare struct padding or blank fields.

Fixes issue 4585.

R=rsc, golang-dev
CC=golang-dev
https://codereview.appspot.com/7142052

https://codereview.appspot.com/7142052/diff/3/test/blank.go
File test/blank.go (right):

https://codereview.appspot.com/7142052/diff/3/test/blank.go#newcode109
test/blank.go:109: 
On 2013/01/18 16:42:28, rsc wrote:
> The T struct above may be zeroed in some implementations. Could you please
force
> the memory to be different, like:
> 
> type T1 struct { x, y, z int }
> 
> *(*T1)(unsafe.Pointer(&t1)) = T1{1,2,3}
> *(*T1)(unsafe.Pointer(&t1)) = T1{4,5,6}
> if t1 != t2 {
>     panic("T{} != T{}")
> }

Done.

[remyoudompheng, 2013-01-18 17:46:30]

Still buggy. Another patch coming.