[Issue 3243] instantiated 'static this()' bring on a compiler message ': __gate is thread local'

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=3243

Kenji Hara <k.hara.pg at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|patch                       |diagnostic
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |---
            Summary|Mixin 'static this()' bring |instantiated 'static
                   |on a compiler message ':    |this()' bring on a compiler
                   |__gate is thread local'     |message ': __gate is thread
                   |                            |local'

--- Comment #5 from Kenji Hara <k.hara.pg at gmail.com> ---
(In reply to David Nadlinger from comment #4)
> This is indeed an invalid bug as far as D2 is concerned, because the static
> constructor is run once per thread and needs a gate variable to prevent
> being run multiple times in the face of separate compilation. I suppose we
> could improve the diagnostic message, though?

The original issue, the mixed-in `static this()` will report ': __gate is
thread local' message with -vtls, is properly fixed from 2.065, by the
side-effect of the commit:

https://github.com/D-Programming-Language/dmd/commit/9f9e4690d6abcfee5858f48a7eb80d1b7eca5a06

Because the mixin is not a proper template instance, the instantiated code is
inserted in the enclosing scope, so the generated `static this()` will be a
non-instantiated function and should not have gate.

But, if the template is properly instantiated, the static this() still needs
TLS __gate variable implicitly as you said, and it will be listed by -vtls. For
example:

template T()
{
    static this() {}
}

class C
{
    alias ti = T!();
}

With 2.068.0,

  dmd -c -vtls test.d

Will show:

  : __gate is thread local

I think this is a minor diagnostic issue. -vlts does not have to list the
internal generated variables like __gate, because it's just confusing.

I change the title and reopen.

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