On Sat, Nov 21, 2009 at 7:21 AM, rahul <[email protected]> wrote:
>>I happen to find this warning very useful, just as I find our policy
>>to make warnings hard errors in our own code helpful.
> Yes, of course. That's a good practice. But what about the end-users
> who have to deal with warnings as hard errors.
I have been meaning to bring this up again. I think I proposed this
before but was shot down.
We should whitelist known compiler versions that build successfully
with -Werror, and then turn it off for the rest. Unless we have a
buildbot tracking a given compiler version, it is likely that -Werror
makes us unable to build with that version of the compiler.
Concrete proposal:
- whitelist the compiler version used on our buildbots to always use -Werror
- turn off -Werror by default on other compilers
- make it easy to turn on -Werror back on if someone wants to fight
some warnings
I have been particularly frustrated with gcc warning bugs that have
been fixed in newer versions of gcc. In older gccs, the following
code produces a "variable may be used uninitialized" warning depending
on your optimization settings.
int x;
{ x = 3; }
printf("%d\n", x);
The fix is to put in a redundant initialization of x, but people
(reasonably) will remove them when working on the code.
Here's a patch I've been working on to add these redundant initializers:
http://build.chromium.org/buildbot/try-server/builders/linux/builds/9235/steps/gclient/logs/patch
Smarter compilers already recognize the existing code is correct, but gcc warns.
Some example changes I have made in this area recently:
"This is needed to work around a gcc bug when building with -Os."
(on the older gcc 4.3 only)
http://src.chromium.org/viewvc/chrome?view=rev&revision=32186
"fix a warning in the process_util unittest" (that only came up on
fta's build, not on our builds on ghardy or karmic)
http://src.chromium.org/viewvc/chrome?view=rev&revision=32648
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