Clarification of __attribute__ init_priority

[Ian Lance Taylor]

Vladimir Simonov <sv@sw.ru> writes:

> 1. "However, GNU C++ allows users to control the order of initialization of objects
> defined at namespace scope with the `init_priority' attribute by
> specifying a relative PRIORITY". Because no "in a given translation
> unit" here does it mean that
> init_priority works over all translation units and has "link unit" scope?

Yes.

> 2. If 1 is true what about anonymous namespace? Is it considered the same namespace
> for different translation units?

I'm not sure what you mean here.  init_priority is a global value.  All
objects with higher priority are constructed before all objects with
lower priority.  This is true whether the objects are defined at global
scope, in a named namespace, or in an anonymous namespace.

> 3. "Note that the particular values of PRIORITY do not matter; only
> their relative ordering." IMO it may be correct only if default
> priority value > 65535.
> But it means that init priority can't be set lover(value greater) then default.
> Is it correct?

All objects with an init_priority attribute are constructed before any
object with no init_priority attribute.

Note that although the documentation doesn't seem to mention it, the
init_priority attribute only works correctly when using the GNU linker
or gold.  As far as I know no other linker implements it.  So you're
fine on GNU/Linux, but on other operating systems you should confirm
that it works.

Ian