[LLVMbugs] [Bug 23235] New: Multiple races reported in std::async (TSan)

[bugzilla-daemon at llvm.org]

https://llvm.org/bugs/show_bug.cgi?id=23235

            Bug ID: 23235
           Summary: Multiple races reported in std::async (TSan)
           Product: libc++
           Version: 3.6
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: All Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: oleg at smolsky.net
                CC: llvmbugs at cs.uiuc.edu, mclow.lists at gmail.com
    Classification: Unclassified

Created attachment 14204
  --> https://llvm.org/bugs/attachment.cgi?id=14204&action=edit
TSan output

I've just noticed TSan warnings when using std::async on Linux. A small example
is below. Compiled with Clang 3.6 and linked against an instrumented version of
libc++:

/opt/clang36/bin/clang++ -std=c++14 -g -fno-omit-frame-pointer
-fsanitize=thread -stdlib=libc++ -fcolor-diagnostics future.cpp -Wl,-rpath
/opt/clang36/lib-tsan -lc++abi -o future



#include <iostream>
#include <memory>
#include <future>
#include <atomic>

std::atomic<int> _counter;

int main()
{
    _counter = 1;

    auto f = std::async(std::launch::async,
                        []{
                            _counter += 2;
                            return true;
                        });
    std::cout << "Result: " << std::boolalpha << f.get() << "\n";
    return 0;
}

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20150415/869afd7b/attachment.html>