Unreliability of the build system

Ian Lynagh ian at well-typed.com
Fri May 17 15:52:58 CEST 2013

On Wed, May 15, 2013 at 12:25:14PM -0700, David Terei wrote:
> I'd point out though that GHC's 'no validate failures' is very
> frequently violated which did confuse me a lot when getting started.

This is at least partly caused by inconsistencies in test results. For
example, a Linux developer might push a change that causes a failure on
OS X, or one person might push a change that means that a perf test
fails on someone else's machine but not his own (or perhaps even fails
randomly, and they got lucky on their validate run).

The first person is not aware that anything is wrong, and the second
person just ignores the failure because their patches didn't cause it.

In an ideal world, the second person would either fix the bug, revert
thc bad change, or file a ticket and mark the test as broken.
Unfortunately, the second person is generally trying to do something
else when they discover the problem, and doesn't want to spend time
fixing something they didn't break.


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