https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69204
Bug ID: 69204
Summary: ThreadSanitizer: False positive on std::promise usage
Product: gcc
Version: 5.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: bugzil...@reto-schneider.ch
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
Target Milestone: ---
When compiling the following code with GCC 5.3.1 (or 5.2.1) and having the
thread sanitizer enabled, a false positive gets reported by TSan.
Code:
#include <atomic>
#include <future>
#include <iostream>
#include <memory>
int main() {
std::promise<void> p;
auto f = std::async(std::launch::async, [&] { p.set_value(); });
p.get_future().wait();
std::cout << "Done!\n";
return 0;
}
Command:
g++-5 -fsanitize=thread -Wall -Wextra -std=c++11 -pthread -static-libtsan
tsan-test.cpp && ./a.out
Expected:
Done!
Actual:
...many lines of stacktraces...
SUMMARY: ThreadSanitizer: data race ??:0
std::unique_ptr<std::__future_base::_Result_base,
std::__future_base::_Result_base::_Deleter>::get() const
==================
Done!
ThreadSanitizer: reported 1 warnings
In my understanding, this code is absolutely correct and Clang 3.6 does also
not see any issues with it.
Compiler:
$ g++-5 -v
Using built-in specs.
COLLECT_GCC=g++-5
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
5.2.1-22ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--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 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)
