New Tool: Prcheck – PRBool’s best friend
Mozilla has a number boolean types and most of them are a form of an int. People expect them to behave like a bool, but since they can be assigned more than 1 value for true, this assumption can lead to bugs. Prcheck will mandate that prbools can only be assigned 1 or 0. Typically static checkers output errors, but prcheck outputs errors & fixes for them in diff format so they can be fixed automatically. See this bug for more info. I think the tool is almost complete. Hopefully, once the MCPP issues described below are addressed, I’ll have one giant patch to eliminate this problem.
MCPP Teething Troubles
Even in the open-source world there are some problems with vendor monoculture. For example we a single vendor providing the C++ compiler and one C preprocessor that is widely used. Even though MCPP is a portable preprocessor that can plug into multiple compilers, it still chokes on some GCCisms. Things are slowly changing and new open source compilers are on the horizon: I can’t wait.
Additionally, since Mozilla is one of the largest projects to be preprocessed with MCPP, we found some scalability bugs in MCPP. The MCPP maintainer addressed those.
Elsa Backend Source Location Work – Works Well?
I am amazed, but hack & slash approach to adding end-of-ast-node info to elkhound still seems to work correctly! It mostly required consulting wikipedia on LR & GLR parsing algorithms to understand how to modify the data structures used in elkhound. I love the combination of Wikipedia and pretty & easy to modify source code.
Publishing My Oink Mods
I have been sending people tarballs on request, due to not being able to integrate my changes into the upstream svn repository. I tried a few svn2hg tools, but they didn’t work very well. hgsvn is good enough to work for OpenJDK, so it might work for me. I’ll try to publish an hg repository of my work within the next week or two.
I’m sorry for not doing this earlier, but it’s extremely time consuming to switch gears from coding oink stuff to trying to package it, especially due to all of the politics involved. Hopefully once the repository is easier to work with I’ll have more people sharing the oink worldload with me. Now that dust settled and the major missing pieces are either implemented or decided upon, a lot of exciting possibilities opened up.
Another day, another piece of preprocessor trivia. Turned out there was an alternative to MCPP that I could have used: gcc’s libcpp. It is common knowledge that gcc uses an integrated preprocessor. It is not so well known that the preprocessor is factored out into what appears to be a mostly standalone library inside of gcc called libgcc. Google barely knows about it and there are no docs or other webpages pointing to it, so i missed it in my search.
This could be a useful project, take libcpp turn it back into a standalone preprocessor and add the cpp undo log comments to it. The only downside of libgcc is that it is GPL which would normally be a pain for BSD-licensed projects, but by turning it back into a standalone tool there is no linking to to worry about.
So if anyone finds implementing the macro-undo log with libgcc interesting, please feel free to do so 🙂
Random Rant on Parallels vs VMWare Fusion vs BootCamp vs 64bit Linux
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