code review 22840043: cmd/cgo: fix handling of array of pointers when using clang

cmd/cgo: fix handling of array of pointers when using clang

Clang does not record the "size" field for pointer types,
so we must insert the size ourselves. We were already
doing this, but only for the case of pointer types.
For an array of pointer types, the setting of the size for
the nested pointer type was happening after the computation
of the size of the array type, meaning that the array type
was always computed as 0 bytes. Delay the size computation.

This bug happens on all Clang systems, not just FreeBSD.
Our test checked that cgo wrote something, not that it was correct.
FreeBSD's default clang rejects array[0] as a C struct field,
so it noticed the incorrect sizes. But the sizes were incorrect
everywhere.

Update testcdefs to check the output has the right semantics.

Fixes issue 6292.

[rsc, 2013-11-07 15:48:30]

Hello golang-dev@googlegroups.com,

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

[iant, 2013-11-07 18:36:59]

LGTM

https://codereview.appspot.com/22840043/diff/40001/misc/cgo/testcdefs/main.c
File misc/cgo/testcdefs/main.c (right):

https://codereview.appspot.com/22840043/diff/40001/misc/cgo/testcdefs/main.c#...
misc/cgo/testcdefs/main.c:47: USED(&ret); // flush return value
s/USED/FLUSH/

[rsc, 2013-11-07 18:38:53]

https://codereview.appspot.com/22840043/diff/40001/misc/cgo/testcdefs/main.c
File misc/cgo/testcdefs/main.c (right):

https://codereview.appspot.com/22840043/diff/40001/misc/cgo/testcdefs/main.c#...
misc/cgo/testcdefs/main.c:47: USED(&ret); // flush return value
On 2013/11/07 18:36:59, iant wrote:
> s/USED/FLUSH/

thanks. my first attempt at this file did not use runtime.h.

[rsc, 2013-11-07 20:24:56]

*** Submitted as https://code.google.com/p/go/source/detail?r=e6794866ebeb ***

cmd/cgo: fix handling of array of pointers when using clang

Clang does not record the "size" field for pointer types,
so we must insert the size ourselves. We were already
doing this, but only for the case of pointer types.
For an array of pointer types, the setting of the size for
the nested pointer type was happening after the computation
of the size of the array type, meaning that the array type
was always computed as 0 bytes. Delay the size computation.

This bug happens on all Clang systems, not just FreeBSD.
Our test checked that cgo wrote something, not that it was correct.
FreeBSD's default clang rejects array[0] as a C struct field,
so it noticed the incorrect sizes. But the sizes were incorrect
everywhere.

Update testcdefs to check the output has the right semantics.

Fixes issue 6292.

R=golang-dev, iant
CC=golang-dev
https://codereview.appspot.com/22840043