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On 07/06/15 22:14, Johannes Huber wrote: |
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> Am Sonntag 07 Juni 2015, 17:08:57 schrieb Michał Górny: |
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>> Hello, developers. |
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> |
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> Hello Michal, |
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> |
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>> As you probably know already, CMake sucks a lot. One of its more |
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>> sucky features is that it generates Makefiles that fail a lot. In |
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>> particular, they fail at verbose build logs that are cluttered |
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>> with useless CMake intermediate commands and hard to read. But |
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>> also they sometimes deadloop hard in faulty dependency scanning |
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>> [1]. |
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>> |
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>> Those two issues can be solved by switching CMake to use Ninja |
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>> instead of make. As you may know, Ninja is the fancy building |
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>> tool that is faster and much harder to use than make. However, it |
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>> integrates with CMake much better and with less hackery. In |
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>> particular, the verbose build log is free of useless CMake |
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>> percentage printing output and other non-sense, and contains only |
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>> real build commands. It also gets dependency scanning right. |
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>> |
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>> Sadly, there are two problems with using Ninja: |
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>> |
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>> 1) it will not work with some packages, |
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>> |
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>> 2) it introduces an extra dep (on Ninja). |
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>> |
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>> The first issue is a bit complex. Sometimes the problem lies in |
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>> CMake itself (not all CMake magic works in Ninja for some |
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>> reason), sometimes in the project (relying on Makefile stuff), |
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>> sometimes in the ebuild. For example, with Ninja you can't do '-C |
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>> subdirectory' to run targets from a specific subdirectory. So, we |
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>> can't force Ninja everywhere. |
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>> |
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>> The second issue is a bit easier. GNU make is part of @system, |
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>> ninja would be considered an extra package being installed. Do we |
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>> consider it fine to require it randomly? Or do we need to justify |
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>> the extra dep by benefits of building a particular package with |
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>> Ninja? Is sane verbose build log a good enough benefit? |
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>> |
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>> So, what do you think? Should I start switching random packages |
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>> to Ninja whenever it works? |
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>> |
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>> Oh, and this would be done via something like: : |
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>> ${CMAKE_MAKEFILE_GENERATOR:=Ninja} |
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>> |
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>> before inherit line. To respect user forcing another generator, |
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>> and to get deps right. |
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>> |
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>> [1]:https://bugs.gentoo.org/show_bug.cgi?id=546336 |
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> |
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> KDE herd maintains ~1000 packages and the majority relies on CMake. |
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> I am not aware of any reports about GNU make related build files. |
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> So i would vote for the reliable GNU make generator. |
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> |
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|
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I tested ninja some while ago on some big cmake science projects and I |
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found it to be faster. So I would vote for Micheals suggestion. Though |
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I also never faced any problems with the makefiles either. It's purely |
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that I found ninja to work smooth and fast. |
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|
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Justin |
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|
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