Saturday, February 23, 2008

Bug or not bug? A Falcon mystery solved

Bug#33184 looked like a tough nut to crack. The initial report was quite clear. Some tests failed on Mac OS X.

I initially assumed that our testing boxes did not include the platform I was using, and informed Hakan. He tested the suite on his box, and reported success.
Too bad. Being able to reproduce a bug is the first step towards its fix. So we exchanged notes on how we compiled the sources. It turned out that I was using the optimized build, while Hakan was using a build with debug options.
I tried with debug options, and indeed, the test suite passed. However, since users are likely to adopt the optimized build, the bug was still confirmed.
More time passed. Hakan made some changes, and the test suite passed in his box, but failed in mine.
Finally, Hakan found the problem. The test suite failed because of the default gcc compiler provided by Apple. Mac OS X 10.4 and 10.5 offer gcc 4.0.1 with Xcode. Apparently, as Hakan found out, there is a bug in the exception handling of Apple's gcc.
After upgrading to gcc 4.2.2, the test suite passed without errors.
Good job, Hakan!

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