http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59056
Bug ID: 59056
Summary: enable_if turns a non-ambiguous template into an
ambiguous one
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: walter.mascarenhas at gmail dot com
Created attachment 31187
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31187&action=edit
a simple code illustrating the bug
The attached file shows that by turning a specialization of
template <class A, class Enable = void>
struct Foo {};
like this one (which works just fine)
template <class A>
struct Foo<A, void>{};
into
template <class A>
struct Foo<A, std::enable_if< typename always_true<A>() >::type >{};
we can get ambigouities, even when typename always_true<A>() >::type
always resolves to void.
For more details, look at the attachement
