Issue #2463 has been reported by David Shao.
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Bug #2463: __thread storage class for errno may break Firefox 17.0esr C++
compilation
http://bugs.dragonflybsd.org/issues/2463
Author: David Shao
Status: New
Priority: Normal
Assignee:
Category:
Target version:
Executing the commands on the file cpperrno.cpp
$ c++ cpperrno.cpp
$ ./a.out
produces the output:
errno = 22
on NetBSD amd64, FreeBSD amd64, and Linux amd64 (Ubuntu 12.04 LTS).
However on DragonFly the output is an error message:
$ c++ cpperrno.cpp
/tmp//ccTk4OGn.o: In function `(anonymous namespace)::__error()':
cpperrno.cpp:(.text+0x10): undefined reference to `(anonymous namespace)::errno'
This matters because the file cpperrno.cpp is a minimal example demonstrating
build breakage of current pkgsrc devel/xulrunner for Firefox 17.0esr, as
reported in a followup to PR pkg/47233.
The difference appears to be that on DragonFly in file sys/sys/errno.h, there
is the declaration:
#if !defined(_KERNEL) || defined(_KERNEL_VIRTUAL)
extern __thread int errno;
Obviously there are reasons to use storage class keyword __thread for errno;
nonetheless, the breakage of compilation for Firefox 17.0esr on no platform but
DragonFly indicates some alternative solution must be devised for porting C++
userland programs.
/* begin cpperrno.cpp */
namespace {
#pragma GCC visibility push(default)
#include <errno.h>
#pragma GCC visibility pop
void innamespace() {
errno = EINVAL;
}
} /* end namespace */
extern "C" {
void seterrno() {
innamespace();
}
} /* end extern */
#include <stdio.h>
#include <errno.h>
int main() {
seterrno();
printf("errno = %d\n", errno);
return errno;
}
/* end cpperrno.cpp */
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