[DragonFlyBSD - Bug #2463] __thread storage class for errno may break Firefox 17.0esr C++ compilation

[David Shao via Redmine <bugtracker-admin@xxxxxxxxxxxxxxxxxxxxx>]

Issue #2463 has been updated by David Shao.


After updating through master
Remove support for ISA adapters.
commit 17f3d27a9030370ecc934704e186d57adaba60f7
Date:   Thu Nov 29 01:52:11 2012 +0100

and removing the local patches commenting out usage of errno, I was able to
bmake replace clean
/usr/pkgsrc/devel/xulrunner successfully on DragonFly x86_64.  I have not had the time to test bmake replace on i386.

devel/xulrunner for Firefox 17.0esr still needs on x86_64 the explicit cast of INT64_MIN to int64_t or a change of the definition of INT64_MIN from LL as illustrated in an update to Bug #2461.
----------------------------------------
Bug #2463: __thread storage class for errno may break Firefox 17.0esr C++ compilation
http://bugs.dragonflybsd.org/issues/2463

Author: David Shao
Status: Feedback
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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