disallow __gshared members without static

[dlangBugzillaToGithub]

Marc Schütz (@schuetzm) reported this on 2014-09-04T09:50:42Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=13421

CC List

• Ketmar Dark

Description

It's surprising that __gshared members are implicitly static. Example:

http://forum.dlang.org/thread/dkqsqyatiwbwyrojpfxb@forum.dlang.org

__gshared members without an explicit `static` should be deprecated with an appropriate message and later disallowed.

(This would also be an excellent candidate for Brian's dfix.)

!!!There are attachements in the bugzilla issue that have not been copied over!!!

[dlangBugzillaToGithub]

ketmar commented on 2014-09-04T11:32:18Z

after some thinking i started to believe that we should make exactly the opposite: warn about 'static __gshared' members. '__gshared' implies "one instance", so 'static __gshared' is excessive and meaningless.

[dlangBugzillaToGithub]

ketmar commented on 2014-09-04T13:27:33Z

Created attachment 1413
warns on "static __gshared" variables

something like this, heh

[dlangBugzillaToGithub]

ketmar commented on 2014-09-04T13:28:19Z

Created attachment 1414
druntime code cleanup

[dlangBugzillaToGithub]

ketmar commented on 2014-09-04T13:28:42Z

Created attachment 1415
phobos code cleanup

[dlangBugzillaToGithub]

schuetzm commented on 2014-09-04T18:37:02Z

`static __gshared` is currently indeed redundant, but my point is that this isn't obvious. I would expect it to work analogously to a shared member: You can have static and non-static ones of those. As I see it, __gshared merely means "make it shared, but don't complain about unsynchronized access".

Therefore I can't agree that it implies "one instance". It's IMO better to make it explicit.

[dlangBugzillaToGithub]

ketmar commented on 2014-09-04T19:43:04Z

specs clearly says:

> __gshared may also be applied to member variables and local variables.
> In these cases, __gshared is equivalent to static, except that the
> variable is shared by all threads rather than being thread local.
http://dlang.org/attribute.html#gshared

so "static __gshared" is a tautology, and i believe that it should be error instead of warning. but error'ing it can break some code, so let's warn for now.