https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65870
Bug ID: 65870
Summary: Explicit function instantiation with default valued
lambda causes duplicate symbol
Product: gcc
Version: 4.9.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: w.shane.grant at gmail dot com
When explicitly instantiating functions with default lambda parameters, g++
generates multiple versions of the lambda with the same symbol names.
I've created a minimal example:
struct Any
{
template <class T>
Any( T const & ){}
};
template <class T>
void func( T t, Any a = [](){} ){}
template void func<int>( int, Any );
template void func<double>( double, Any );
int main()
{
func( 3 );
func( 3.0 );
return 0;
}
Compiled with g++ -std=c++11 (4.7.4, 4.8.3, and 4.9.1) , this causes the error:
/tmp/ccND7XlM.s:104: Error: symbol `_ZN3AnyC2IUlvE_EERKT_' is already defined
If this is indeed incorrect behavior (I don't know enough about the spec to
confirm this), I believe the problem is that the name mangling for the lambda
is not taking the parent template into account.
