i am new to c++ lambda, and trying to use it. Please excuse me if my bug
reports are invalid.
here is something i wished would work, but doesn't.
auto sum = [&term,&next,&sum](int a, int b)mutable ->int
{
if(a>b)
return 0;
else
return term(a) + sum(next(a),b);
};
It gives compilation error:
vi...@linux-718q:~/Study/09C++/c++0x/lambda> g++ -g -std=c++0x sum.cpp
sum.cpp: In lambda function:
sum.cpp:13:36: error: ((<lambda(int, int)>*)this)-><lambda(int, int)>::sum
cannot be used as a function
Then i changed the recursive lambda as follows:
std::function<int(int,int)> sum = [&term,&next,&sum](int a, int b)->int
{
if(a>b)
return 0;
else
return term(a) + sum(next(a),b);
};
this seems to compile but gives a core dump.
the gdb report is:
vi...@linux-718q:~/Study/09C++/c++0x/lambda> gdb a.out
GNU gdb (GDB) SUSE (6.8.91.20090930-2.4)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i586-suse-linux".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/vimal/Study/09C++/c++0x/lambda/a.out...done.
(gdb) run
Starting program: /home/vimal/Study/09C++/c++0x/lambda/a.out
Missing separate debuginfo for /lib/ld-linux.so.2
Try: zypper install -C
"debuginfo(build-id)=d7706cbaa0ca09319cb645eac789cb8399078797"
Missing separate debuginfo for /lib/libm.so.6
Try: zypper install -C
"debuginfo(build-id)=a488c775caa0433cb23f9764d683150f40872ef1"
Missing separate debuginfo for /lib/libc.so.6
Try: zypper install -C
"debuginfo(build-id)=ee302691046515fe3766ae3b7d47afd3e3a8d063"
Program received signal SIGSEGV, Segmentation fault.
0x0804889b in _Base_manager<<lambda(int, int)> >::_M_get_pointer(const
std::_Any_data &) (__source=...)
at
/usr/local/lib/gcc/i686-pc-linux-gnu/4.5.0/../../../../include/c++/4.5.0/functional:1569
1569 /* have stored a pointer */ :
__source._M_access<_Functor*>();
(gdb)
--
Summary: core dump in recursive lambda function
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: vimal78 at gmail dot com
GCC build triplet: version 4.5.0 20091231 (experimental)
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42741
