https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89605
Bug ID: 89605
Summary: A method cannot have two identical lambdas as default
arguments
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: xavier at cremaschi dot fr
Target Milestone: ---
$ g++ --version
g++ (Debian 8.2.0-21) 8.2.0
The following code does not compile :
#include <string>
#include <functional>
#include <iostream>
using namespace std;
class S {
public:
using ConverterFunction = function<double(double)>;
void _foo(
const ConverterFunction& converter = [](double value) -> double
{ return value; },
const ConverterFunction& converterBack = [](double value) ->
double { return value; }
);
};
void S::_foo(
const ConverterFunction& converter,
const ConverterFunction& converterBack)
{
cout << "foo " << converter(42) << endl;
}
int main() {
S s;
s._foo();
return 0;
}
It triggers the following error :
/tmp/ccW5xjuM.s: Assembler messages:
/tmp/ccW5xjuM.s:183: Error: symbol
`_ZZN1S4_fooERKSt8functionIFddEES4_Ed_NKUldE_clEd' is already defined
/tmp/ccW5xjuM.s:514: Error: symbol
`_ZSt4moveIRZN1S4_fooERKSt8functionIFddEES5_Ed_UldE_EONSt16remove_referenceIT_E4typeEOS9_'
is already defined
/tmp/ccW5xjuM.s:534: Error: symbol
`_ZNSt8functionIFddEEC2IZN1S4_fooERKS1_S5_Ed_UldE_vvEET_' is already defined
/tmp/ccW5xjuM.s:788: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E21_M_not_empty_functionIS7_EEbRKT_'
is already defined
/tmp/ccW5xjuM.s:807: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E15_M_init_functorERSt9_Any_dataOS7_'
is already defined
/tmp/ccW5xjuM.s:836: Error: symbol
`_ZNSt17_Function_handlerIFddEZN1S4_fooERKSt8functionIS0_ES5_Ed_UldE_E9_M_invokeERKSt9_Any_dataOd'
is already defined
/tmp/ccW5xjuM.s:873: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E10_M_managerERSt9_Any_dataRKS9_St18_Manager_operation'
is already defined
/tmp/ccW5xjuM.s:1099: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E15_M_init_functorERSt9_Any_dataOS7_St17integral_constantIbLb1EE'
is already defined
/tmp/ccW5xjuM.s:1129: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E14_M_get_pointerERKSt9_Any_data'
is already defined
/tmp/ccW5xjuM.s:1156: Error: symbol
`_ZNSt9_Any_data9_M_accessIPZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_EERT_v' is
already defined
/tmp/ccW5xjuM.s:1178: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E8_M_cloneERSt9_Any_dataRKS9_St17integral_constantIbLb1EE'
is already defined
/tmp/ccW5xjuM.s:1208: Error: symbol
`_ZNSt14_Function_base13_Base_managerIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_E10_M_destroyERSt9_Any_dataSt17integral_constantIbLb1EE'
is already defined
/tmp/ccW5xjuM.s:1297: Error: symbol
`_ZNKSt9_Any_data9_M_accessIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_EERKT_v' is
already defined
/tmp/ccW5xjuM.s:1319: Error: symbol
`_ZSt11__addressofIKZN1S4_fooERKSt8functionIFddEES5_Ed_UldE_EPT_RS8_' is
already defined
/tmp/ccW5xjuM.s:1339: Error: symbol
`_ZNSt9_Any_data9_M_accessIZN1S4_fooERKSt8functionIFddEES6_Ed_UldE_EERT_v' is
already defined
The exact same code compiles with clang++-6.0 or MSVC (Visual Studio 2017
15.9.4).
It also compiles with g++ as soon as implementation is inlined in class
definition.
