• via Digitalmars-d-bugs (34/34) Nov 11 2014 https://issues.dlang.org/show_bug.cgi?id=13712

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=13712

          Issue ID: 13712
           Summary: Templates don't resolve their static dtor order
                    depending on passed in type
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: DMD
          Assignee: nobody puremagic.com
          Reporter: Marco.Leise gmx.de

Whenever we have static dtors in templates, we risk that the template arguments
introduce a "hidden" dependency. Usually destructor call order is resolved by
looking at imported modules. In case of templates, their surrounding module
does not need to import any other modules to be able to use a type `T`. Now if
`T` itself comes out of a module with static dtors, that otherwise has no
connection with the template and module in question, the compiler will not take
note of it and the runtime may call static dtors from both module in the wrong
order.

This usually leads to access violations on application shutdown.
A typical example where this happens is when you have one module with a
singleton template, where a shared dtor destroys it, and another module with
some globally managed templated resource. Now if you create a singleton class
containing such a resource, the singleton's module misses that it depends on
the resource's module for construction/destruction.

When instantiating a template the compiler must emit dependencies for the
module containing the template on any types used in the template arguments,
whether they are passed in directly or as part of an alias expression such as a
function return type. Before that, we cannot safely use singletons and other
global resources in D.

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