[Bug c++/84368] New: [8 Regression] return type of generic lambda in variadic lambda in template is not deduced
benni.buch at gmail dot com
gcc-bugzilla@gcc.gnu.org
Tue Feb 13 16:56:00 GMT 2018
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84368
Bug ID: 84368
Summary: [8 Regression] return type of generic lambda in
variadic lambda in template is not deduced
Product: gcc
Version: 8.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: benni.buch at gmail dot com
Target Milestone: ---
template < typename ... T >
void sink(T ...){}
template < typename ... T >
void foo(T ... v){
[](auto ... v){
auto bar = [](auto, auto){ return 0; };
sink(bar(v, T{}) ...);
}(v ...);
}
int main(){
foo(0);
}
$ g++ -std=c++14 main.cpp
main.cpp: In instantiation of 'foo(T ...) [with T = {int}]::<lambda(auto:1
...)> [with auto:1 = {int}]':
main.cpp:9:6: required from 'void foo(T ...) [with T = {int}]'
main.cpp:13:10: required from here
main.cpp:8:17: error: use of 'bar' before deduction of 'auto'
sink(bar(v, T{}) ...);
~~~^~~~~~~~
$ g++ --version
g++ (GCC) 8.0.1 20180213 (experimental)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Known to work with GCC 5 and 6:
$ g++-6 --version
g++-6 (Ubuntu/Linaro 6.3.0-18ubuntu2~16.04) 6.3.0 20170519
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ g++-5 --version
g++-5 (Ubuntu 5.4.1-2ubuntu1~16.04) 5.4.1 20160904
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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