`std::uncaught_exception()` true when it should not be anymore

[llvmbot]

Bugzilla Link	23193
Version	3.6
OS	FreeBSD
Reporter	LLVM Bugzilla Contributor
CC	@DougGregor

Extended Description

I wrote a test suite for Zipios++ (https://sourceforge.net/projects/zipios/) using Catch.hpp (https://github.com/philsquared/Catch).

There seems to be a problem with std::uncaught_exception() when I run the code under FreeBSD 10.1 with version 3.4.1 of clang. (20140512)

The software will throw exceptions that are gobbled in some way (caught), but std::uncaught_exception() continues to return true on normal return.

    // here std::uncaught_exception() is false
    run_a_test();
    // here std::uncaught_exception() is true

One example where I get the problem, a streambuf throws an exception which is caught in the read() function of the iostream implementation (as expected) but then std::uncaught_exception() remains true even though the try/catch should have cleared it.

The easiest way to reproduce is to get FreeBSD, compile Zipios++ and run the test suite. With a copy of catch.hpp (single header file) under contrib/... you can just type:

    dev/build

and that will happen.

Note that I commented out a certain number of tests at this time. You probably want to edit the tests/catch_zipfile.cpp and remove the #ifndef __clang__ to make sure you get the errors. Without those guards it is reproducible by just these two or three tests where such appears.

Let me know if you need any help with getting things to replicate the problem.

[llvmbot]

Fixed platform/version fields.

[llvmbot]

I've verified that this occurs on clang 3.6.2 on the Linux platform as well. I unfortunately was not able to whittle down a simple example.

It seems like std::uncaught_exception() is returning true when it shouldn't be.

[llvmbot]

I've verified that this occurs on clang 3.6.2 on the Linux platform as well.
I unfortunately was not able to whittle down a simple example.

It seems like 'std::uncaught_exception()' is returning 'true' when it
shouldn't be.

Someone using catch.hpp was able to write a "very small test example" that exhibit the same problem. The thread can be found here:

catchorg/Catch2#271

It looks like people still have the issue as other posts reference the same problem every now and then. I'm fine with my current version of g++, only clang causes the problem.

[llvmbot]

Hi, on FreeBSD this can easily be reproduced. The assertion in the program below fires, when the program is compiled with
clang++ on FreeBSD (the default compiler):

#include <stdexcept>
#include <cassert>

int main() {
    try {
        throw std::runtime_error("test");
    }
    catch (...) {
        try { 
            throw;
        }
        catch (...) {
        }
    }
    assert (!std::uncaught_exception());
}

$ clang++ --version
FreeBSD clang version 4.0.0 (tags/RELEASE_400/final 297347) (based on LLVM 
4.0.0)
Target: x86_64-unknown-freebsd11.1
Thread model: posix
InstalledDir: /usr/bin

[llvmbot]

Turned out this was a bug in libcxxrt, which just has been fixed. For reference: https://github.com/pathscale/libcxxrt/issues/49