-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On 02/27/2014 03:11 PM, Karl Tomlinson wrote: > Daniel Holbert writes: > >> On 02/27/2014 10:26 AM, Zack Weinberg wrote: >>> Does that mean a patch to squelch the uninitialized variable >>> warnings in layout will now be accepted? Those are the only >>> warnings in layout on my (Linux, debug) builds. >>> >>>> layout/base/FrameLayerBuilder.cpp:3462:56 >>>> [-Wmaybe-uninitialized] ?last? may be used uninitialized in >>>> this function >> >> If there's no perf impact, then probably, for at least some of >> them! >> >> The merits of maybe-uninitialized warning-fixes can vary on a >> case-by-case basis, because in some cases, it's just a false >> positive and the only way to "fix" it has a (small) perf cost. >> (which is why we don't treat it as an error in warnings-as-errors >> builds) > > More that just a perf cost. > > Explicitly initializing variables to garbage can hide real bugs > from tools such as valgrind if they really are never set correctly > later. > > Treating these as warnings, not errors, is probably the best thing > here. If you see the warning and you've recently changed that > code, then check it. If you haven't, you see the "may be" and > ignore it.
This is exactly the same thing dbaron said the last time I brought this up (quite some time ago - 2010, maybe?) I didn't buy it then and I don't buy it now. I think it is far more likely that a maybe-used-uninitialized true positive will *go unnoticed* because we've trained ourselves to ignore those warnings, and I don't think better precision in a valgrind run is worth the risk of letting a true positive slip through in a release build. Those bugs tend to be security critical. I also defy anyone to demonstrate a measurable performance impact from the tiny amount of additional machine code that might be emitted if we added initializations to squelch all those warnings. zw -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iQIcBAEBCAAGBQJTD6OyAAoJEJH8wytnaapkaesQAI41/f22D3qEkEklw9WctsAp yJ2SpQ3fRu+HWenONIRNyKLWYZoYFX876Ef4oOJ9ebBVqx0DjwOS8NZjZRhZDZ89 DSLMpZUpgn4ZdEG+FWYAhV0deSdC6VeYnwrb2VB2exKr+rcoaLN9ksWDg8YkDyWo 2DO2rbL4QUj49OeECAQ8HP+iuEO9pqQsGowz5vK2wqr4cMiJVLXajM1QLWht+fVE JW5caOWmp9sJ9raG9C7OucFM7sgdAbe/Y3mi7WTKPMgv0Bq7FUFxxFM45aiV54c6 6l6oNJPN1Gmwv7YHW+J/jRqaTqJL2i6Uu3vorY4Vm2eF8V7DwkK/NVV8xnRumCEO NzFh67UCIVdSm6Ae5+UyRK0n5yPtRnSu13xbloe6glnBFqhYeQMrY1ouNqc6431Q 8662zVuFgL0swl7rJv9Wtz+5QpJesOPUrlPouRf8I4yxHwz/6OYW/wYg6QuDs4qa /R0mk7TSk0lKSCjSZzrWWo5M/6INSTbOtrfy7brsSy5LjnWKEVST0sBBvb4W3nqA TP0JNCm9KariKz8V8IUB5JI/LIl7J8//Sl5lsZ6q/ySn+tjzzIvWYnH3LE1i0TSk l3SYstBMf5msC0whXGCdZ8/JqCwWr+GNIjJSAKXkMNctRSileo4grvaftU5YZ7C3 O31oxvtOd7EfYvzstgDh =jHW4 -----END PGP SIGNATURE----- _______________________________________________ dev-platform mailing list [email protected] https://lists.mozilla.org/listinfo/dev-platform
