http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53660
Bug #: 53660
Summary: function pointer conversion function template with
nested-name-specifier ignored
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: pot...@mac.com
template< bool >
struct enable_if { typedef void (*t)(); };
struct c {
template< bool t = true >
operator typename enable_if< t >::t () { return []{}; }
};
int main() {
c()(); // error: no match for call to ‘(c) ()’
}
http://stackoverflow.com/questions/11018810
In C++03 it seems that it was impossible to define a conversion function
template that would render its class Callable. Yet there is a function
add_template_conv_candidate (cp/call.c) which seems to be used only for this
purpose. It was added back in 1997 and it's not clear that it's been tested in
a while. Now with default function template arguments the above construct is
possible, and it should be called but isn't.
The problem is that the test for function pointer type (etc.) is applied before
instantiation in build_op_call_1. The test probably belongs in
add_conv_candidate.
