[cmake-developers] Quiet option for cmake

[Craig Scott]

On Thu, Aug 23, 2018 at 8:02 PM, Craig Scott <craig.scott at crascit.com>
wrote:

>
>
> On Thu, Aug 23, 2018 at 4:40 AM, Brad King <brad.king at kitware.com> wrote:
>
>> On 08/21/2018 05:04 PM, Craig Scott wrote:
>> > A user has recently been asking about reducing the output coming from a
>> > FetchContent population when nothing needs to be done
>> > Because this is implemented as a sub-build, you always see the following
>> >
>> > -- Configuring done
>> > -- Generating done
>> > -- Build files have been written to: ...
>>
>> Isn't that output coming from the invocation here:
>>
>>   https://gitlab.kitware.com/cmake/cmake/blob/v3.12.1/Modules/
>> FetchContent.cmake#L776-781
>>
>> rather than inside ExternalProject?
>>
>
> Yes, that is where I'd like to be able to use the proposed --quiet or
> --silent option.
>
>
>
>>
>> Why is that output not always captured?
>>
>
> If you capture it, then you don't get to see it until the command has
> completed. It can take non-trivial time and in some cases may require user
> input (e.g. to enter a password for a private SSH key). If you captured the
> output and the download hung for some reason, there would be no output to
> give any indication of where the download was up to. For cases where you
> don't expect problems, you can use the QUIET option and the output is
> indeed captured and only output at the end. This is the default because
> otherwise the output is rather noisy with all the ExternalProject step
> logging. But for cases where you need to investigate problems, you don't
> want the output captured.
>
> Now that I've said all that, I guess FetchContent could check if the
> output of a QUIET run was just the above-mentioned three lines and drop
> them to leave no output in that case. Might be the simpler solution.
> Furthermore, for the second execute_process() call a few lines after the
> one referenced above (which does the build stage of the sub-build), we
> could potentially make use of the logging verbosity improvements in MR
> 2129 <https://gitlab.kitware.com/cmake/cmake/merge_requests/2129> if/when
> it is done to further minimise the output of the "nothing to do" case.
>
>
Sorry, got my wires crossed a bit there. The QUIET option already fully
absorbs the output unless there's an error. I missed this in the original
issue that prompted this request. Let me go back to that issue and see if
there's really anything needed here after all.


-- 
Craig Scott
Melbourne, Australia
https://crascit.com

New book released: Professional CMake: A Practical Guide
<https://crascit.com/professional-cmake/>
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