Public bug reported:
I didn't see this bug when I searched, so I apologize if it is a
duplicate. cc1plus segfaults when I (ab)use recursive template
definitions. Take a look at the offending code below, which I placed in
a file called test.cpp.
[code]
#include <iostream>
template <int N>
void print()
{
print<N - 1>();
std::cout << N << std::endl;
}
template <>
void print<0>()
{
}
int main()
{
print<1000000>();
return 0;
}
[/code]
Building without -ftemplate-depth, the compiler gives an error, as
expected.
[code]
neal@OK:~/Desktop$ g++ test.cpp -o test
test.cpp: In function ‘void print() [with int N = 998977]’:
test.cpp:7:4: error: template instantiation depth exceeds maximum of 1024 (use
-ftemplate-depth= to increase the maximum) instantiating ‘void print() [with
int N = 998976]’
test.cpp:7:4: recursively instantiated from ‘void print() [with int N =
999999]’
test.cpp:7:4: instantiated from ‘void print() [with int N = 1000000]’
test.cpp:18:19: instantiated from here
[/code]
Building with -ftemplate-depth=1000000 causes a segfault.
[code]
neal@OK:~/Desktop$ g++ test.cpp -o test -ftemplate-depth=1000000
g++: internal compiler error: Segmentation fault (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.6/README.Bugs> for instructions.
[/code]
According to the 2003 standard, the recursive template limit is
implementation defined. I understand that there is a machine limit to
the possible depth of a template definition, and that nobody in their
right mind would write code like this. However, instead of having the
code just segfault (which produces no useable error message), you should
try to terminate gracefully.
Here is some more system information.
[code]
neal@OK:~/Desktop$ lsb_release -rd
Description: Ubuntu 12.04.1 LTS
Release: 12.04
neal@OK:~/Desktop$ apt-cache policy g++
g++:
Installed: 4:4.6.3-1ubuntu5
Candidate: 4:4.6.3-1ubuntu5
Version table:
*** 4:4.6.3-1ubuntu5 0
500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
100 /var/lib/dpkg/status
[/code]
ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gcc-4.6 4.6.3-1ubuntu5
ProcVersionSignature: Ubuntu 3.2.0-31.50-generic 3.2.28
Uname: Linux 3.2.0-31-generic x86_64
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
Date: Sun Oct 7 16:28:26 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64
(20120823.1)
ProcEnviron:
TERM=xterm
PATH=(custom, user)
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: gcc-4.6
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: gcc-4.6 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug precise running-unity
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https://bugs.launchpad.net/bugs/1063415
Title:
cc1plus segfaults when using deeply recursive template definitions
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