Tinderbox summary for May 2010: GCC 4.5, Berkeley DB 5.0; libpng 1.4

I’m a bit surprised sincerely, and not exactly in a good way, since I started with GCC 4.5 just over a month ago, that the tinderbox almost caught up with its queue already.

Now, admittedly part of the reason might be related to my optimisation of the filesystems and partitions — especially after last week, since I moved all the stuff around to divide it into three pairs of disks: two 320GB WD RAID Edition disks for the RAID1 with the OS, my home and work stuff; two 500G Samsung disks for the “scratch” partitions (/var/tmp, the tinderbox’s filesystem), and finally two 1TB WD Caviar Green for storage space (multimedia files, including samples, and distfiles, 150GB of them!).

What makes me doubtful regarding the goodness of this situation is that a lot of packages were skipped because of dependencies failing. With GCC 4.5 we have no MySQL; with Berkeley DB 5.0 we have no Apache (because of apr-util). Without those, the tinderbox drops tons and tons of packages, a whole deptree of packages that will not be tested until the roots are fixed.

At any rate, now that I actually went through the packages, I can finally say what the most common problems with GCC 4.5 are. And surprisingly, it comes down to mostly two problems, a nasty runtime one, and one “usual” boring one.

First of all, the nasty one: GCC now seem to provide runtime-based overflow protection, not totally unlike the Stack Smashing Protection that the Gentoo Hardened project used to provide (and thanks to Magnus might come back at providing); this is a good thing from one side, because overflow protection is a nice safety feature (if not a security one), but it also means that we’re going to find a lot of packages failing at runtime because of this, and that stuff is much harder to deal with; one such package is the TCL interpreter, that is overflowing at runtime for so many packages that it’s boring. The problems tied to these features have their own tracker that was started back into 4.3 series already.

The boring problem is, once again, related to C++ (can you see why Luca is so worried now?): for some reason, up until now GCC supported one very strange syntax for it:

Foo::Bar x = Foo::Bar::Bar();

This basically consists of explicitly calling the constructor function of the class, rather than using the constructor through conversion. I would have always considered this syntax invalid, since I started learning the language, but I can tell how it could be typed wrongly; what surprised me is that it was allowed before. Sigh. The fact that Free Software has become a strict GCC monoculture does not help here, it means that instead of actually being tested, the code is just accepted if GCC supports it. It sucks now that LLVM seems to become more interesting.

The Berkeley DB situation is much worse, I’m afraid, in term of time needed to solve it; the main problem there is that a lot of packages that fail with it fall into the mail software categories, and the net-mail team is near non-existant for way too long now. This can be noted by the fact that we have stuff like mailx failing, continuous file collisions that are not being solved (and the tentatives with the “mailwrapper” stuff resulted in a total revert), and generally broken and out of date packages.

We could use a few more “mailmen” working in Gentoo, since I most definitely have just barely enough clue to manage my postfix installs with the help of The Definitive Guide (that’s one of the best thing I could buy from O’Reilly, without that I’d be seriously screwed).

6 thoughts on “Tinderbox summary for May 2010: GCC 4.5, Berkeley DB 5.0; libpng 1.4

  1. Amen for the more “mailmen” request! I’ve done a few fixes for courier-imap, but more gentoo devs that know their mail software would be nice

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  2. Wrt the Class constructor function issue, GCC makes me wonder about my C++ knowledge. Since I first seen this kind of bug, I was confused I must say whether is syntax was valid in the past or not. I think GCC people need to pay attention to this area and not just import fuzzy rules

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  3. GCC should have stopped accepting this code earlier, yes. But it should never have done it in the first place as it’s simply not valid C++. That people think everything accepted by their compiler is valid is the real problem. Along with the fact that C++ is a complex language with quite a few corner cases and no really good compilers for a very long time.At least GCC is getting stricter, compare it to HTML where browser still accept lots and lots of garbage just because Netscape or IE did once and it got common.

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  4. The code was valid C++98, and it wasn’t a constructor call. In C++98, in every class C, the name C exists as both a constructor and a type name, but the constructor could only be used in certain contexts such as a function declaration. In other contexts, C::C simply means C. C::C::C::C::C was also a perfectly valid way to refer to class C. Only later did there turn out to be a need to refer to the constructor in more contexts, and at that point C::C was changed from a typename to a constructor. GCC 4.4 and earlier follow the original C++ standard in this respect, GCC 4.5 follows the updated standard.

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