http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55655
Bug #: 55655
Summary: cannot export specialized template
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: [email protected]
ReportedBy: [email protected]
Let us say I have a generic template class, e.g. my_smart_ptr. Let us also say
I have a class 'foo', 'clas foo : public my_smart_ptr<bar>' that is part of
some library public API. And last, let us say that 'foo' needs to specialize
'my_smart_ptr<bar>'.
As far as I can tell, it is impossible to export this instantiation with proper
symbol visibility in this configuration. I do NOT want to make all possible
instantiations of my_smart_ptr have default visibility (someone, somewhere may
have an instantiation that should have hidden visibility).
I need to do two things, but they are mutually contradictory:
1. I need to explicitly instantiate the template in order to give it default
visibility. However, if I do this first, it prevents specialization. (I also
get compiler errors for my specific use case, as generic instantiation is not
possible.)
2. I need to declare specialization prior to instantiation. However, if I do
this before instantiation, I cannot set default visibility on the instantiation
and I get link errors.
I think there should be a way to do this... Right now I am forced to not export
the template, requiring each user to use their own instantiation, which creates
a fragile ABI.
