[llvm-commits] [llvm] r89211 - /llvm/trunk/CMakeLists.txt

[Nick Lewycky]

Daniel Dunbar wrote:
> On Sun, Nov 22, 2009 at 10:51 AM, Nick Lewycky<nicholas at mxc.ca>  wrote:
>> Daniel Dunbar wrote:
>>>
>>> On Thu, Nov 19, 2009 at 1:15 PM, Óscar Fuentes<ofv at wanadoo.es>    wrote:
>>>>
>>>> Hello Daniel.
>>>>
>>>> Daniel Dunbar<daniel at zuster.org>    writes:
>>>>
>>>>> URL: http://llvm.org/viewvc/llvm-project?rev=89211&view=rev
>>>>> Log:
>>>>> Turn LLVM_BUILD_EXAMPLES off by default in CMake builds, to match
>>>>> Makefiles&
>>>>> Clang.
>>>>
>>>> What's the rationale for this?
>>>>
>>>> (And wouldn't it warrant the corresponding update of docs/CMake.html,
>>>> where default values for variables are listed?)
>>>
>>> The rationale for changing the default (for cmake and make, I assume
>>> we agree they should have the same default) is that most people
>>> building LLVM don't care about the examples (because they are
>>> developers), and this greatly increases cycle times because of the
>>> sheer number of link steps it adds. Having examples be "optional"
>>> builds for people exploring LLVM seems reasonable to me, the only
>>> value I see in building them regularly is to prevent them from being
>>> out-dated, but I will change (one, fast) buildbot to maintain that.
>>>
>>> I will update the doc.
>>
>> The rationale for copying each Kaleidoscope chapter into the examples/
>> directory was to make sure that our examples on the website don't get out of
>> date when someone changes the API.
>
> I agree this is good.
>
>> This just means that people will run make and make check, commit, and then
>> discover that their change somehow broke the buildbots. It'd be nice to
>> notice and resolve the breakage before committing.
>
> I explained my view on this with my reply to Duncan, and there is no
> counterargument here. I can quite easily argue that the increased
> cycle time of the buildbots (and the corresponding improvement in
> blamelist accuracy) as a group more than makes up for the rare times
> when someone breaks an example.

I know. I'm not convinced that it is so rare, else we wouldn't have 
needed to add it in the first place. I realize that at least getting it 
caught by the buildbots is better than the situation from before they 
were added (nobody noticing until a new users complains on our IRC 
channel) but I remain an unfan of this change -- just not strongly 
enough to strongly enough to keep pushing back on it. Whoever cares the 
most wins, I guess :) Hopefully it won't lead to too many reversions of 
otherwise good changes.

Nick