code review 7388049: runtime: add cgocallback_gofunc that can call Go func value

runtime: add cgocallback_gofunc that can call Go func value

For now, all the callbacks from C use top-level Go functions,
so they use the equivalent C function pointer, and will continue
to do so. But perhaps some day this will be useful for calling
a Go func value (at least if the type is already known).

More importantly, the Windows callback code needs to be able
to use cgocallback_gofunc to call a Go func value.
Should fix the Windows build.

[rsc, 2013-02-22 21:08:55]

Hello ken2 (cc: golang-dev@googlegroups.com),

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

[rsc, 2013-02-22 21:08:59]

*** Submitted as https://code.google.com/p/go/source/detail?r=91778e3920ae ***

runtime: add cgocallback_gofunc that can call Go func value

For now, all the callbacks from C use top-level Go functions,
so they use the equivalent C function pointer, and will continue
to do so. But perhaps some day this will be useful for calling
a Go func value (at least if the type is already known).

More importantly, the Windows callback code needs to be able
to use cgocallback_gofunc to call a Go func value.
Should fix the Windows build.

R=ken2
CC=golang-dev
https://codereview.appspot.com/7388049

[ken3, 2013-02-23 06:32:13]

lgtm