http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55394
Bug #: 55394
Summary: Using call_once without -lpthread compiles without
warning
Classification: Unclassified
Product: gcc
Version: 4.6.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: g.j.gieze...@uu.nl
Created attachment 28731
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28731
Source file
A source file which contains call_once will compile without any errors or
warnings, even when libpthread is not linked. At run time, an exception will be
thrown with a very unhelpful message. The attached source file demonstrates the
problem.
$ g++ -Wall -Wextra -std=c++0x callonce.cpp
$ ./a.out
terminate called after throwing an instance of 'std::system_error'
what(): Unknown error -1
Aborted (core dumped)
Linking libpthread will remove the problem.
$ g++ -Wall -Wextra -std=c++0x callonce.cpp -lpthread
$ ./a.out
$
In the actual use case, call_once was called in a library that could be used in
both multithreaded and singlethreaded code. That made it a hard to trace bug.
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object
--enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
