Autotools vs CMake for both Windows and Linux compilation

Question

I have been looking for pros & cons of Autotools and CMake. But I would like to know opinions from people having used one (or both) of these tools for projects.

I used Autotools very basically a year ago and I know that one of the good points is that it relies on shell scripting, thus it does not need to be installed to be run and uses portable shell scripting. But it looks like it is too unix oriented, and it would not be possible to run the configure file on Windows.

I have now to choose a build system tool for an open source project that will have to be compiled for at least Linux & Windows. It is written in C++, and uses a Qt GUI front-end, the rest of it is "generic".

Thanks for you help.

Answer 1

I would not recommend autotools for Windows. Use CMake.

Why? Windows doesn't have a native sh.exe, and the emulation is slow. It's also very easy to get configury stuff wrong. I'm not saying it's impossible in CMake, but CMake surely abstracts more away, so you worry about less. CMake documentation can be a bit hard to read, but once it's set up, you should be fine for all toolchains ever supported by CMake. CMake also integrates testing, packaging etc...

Autotools is slow on Windows, does not work easily with MSVC, and has weird quirks with Windows (and other OSes) that are hard to debug, and hard to fix. libtool also sucks on Windows, where it often refuses to build a shared library even, if you think it should and could. Toolchain relocation issues are also prevalent with libtool, which may look at the wrong files in a user's toolchain. CMake is a lot easier in this regard. It assumes normal things about the target platform and creates generic and good build instructions.

Also, CMake has coloured output :) and nice progress percentages.

PS: I just have some experience with CMake and autotools on Windows as a user. CMake tends to work, autotools tends to bite your ear off when you're not looking, and smile at you when it fails due to some strange error...

Answer 2

Updated 16th of January 2019: Refined advice as tools evolve.

I have used autotools before for a considerable amount of time.

Currently I make intensive use of meson and cmake only when I need it.

Some personal advice:

1. for big teams, stick to CMake if you want to make use of the generators for XCode. If you do not need it, I would use Meson directly. Meson, as of version 0.49, also supports finding CMake configuration files (though I did not test yet how well this works). Also, Visual Studio seems to be sufficiently well-supported at this point in time, though, again, I did not try myself. The advantage of CMake is that it has Visual Studio integration.

2. Drop autotools. Meson covers well everything already. Their cross-compilation model is amazingly understandable. In CMake, last time I checked, everything was quite more difficult.

I have also tried scons, waf, and tup.

The most full-featured, cross-platform system, is CMake, but the DSL from meson will be easier to use for people used to python and others. Meson is starting to support VS also (a VS2015 generator) and some projects already have experimental support for it, for example gstreamer. Gstreamer is compiled in windows as well with meson. Right now there is VS2015 generator and VS2017 but I did not try myself the generators lately. As of meson 0.37.1 needed some work, but they are improving them and current version is already 0.40.

Meson

Pros:

• The DSL does not get in the way at all. In fact, it is very nice and familiar, based in python.
• Well-thought cross compilation support.
• The objects are all strongly typed: you cannot make string substitution mistakes easily, since objects are entities such as 'depencency', 'include directory', etc.
• It is very obviuos how to add a module for one of your tools.
• Cross-compilation seems more straightforward to use.
• Really well-thought. The designer and main writer of Meson knows what he talks about very well when designing a build system.
• Very, very fast, especially in incremental builds.
• The documentation is 10 times better that what you can find in cmake. Go visit http://mesonbuild.com and you will find tutorial, howtos and a good reference. It is not perfect but it is really discoverable.

Cons:

• Not as mature as CMake, though, I consider it already fully usable for C++.
• Not so many modules available, though, gnome, qt and the common ones are already there.
• Project generators: seems VS generator is not working that well as of now. CMake project generators are far more mature.
• Has a python3 + ninja dependency.

Cmake

Pros:

• Generates projects for many different IDEs. This is a very nice feature for teams.
• Plays well with windows tools, unlike autotools.
• Mature, almost de-facto standard.
• Microsoft is working on CMake integration for Visual Studio.

Cons:

• It does not follow any well known standard or guidelines.
• No uninstall target.
• The DSL is weird, when you start to do comparisons and such, and the strings vs list thing or escape chars, you will make many mistakes, I am pretty sure.
• Cross compilation sucks.

Autotools

Pros:

• Most powerful system for cross-compilation, IMHO.
• The generated scripts don't need anything else than make, a shell and, if you need it to build, a compiler.
• The command-line is really nice and consistent.
• A standard in unix world, lots of docs.
• Really powerful command-line: changing directories of installation, uninstall, renaming binaries...
• If you target unix, packaging sources with this tool is really convenient.

Cons:

• It won't play well with microsoft tools. A real showstopper.
• The learning curve is... well... But actually I can say that CMake was not that easy either.
• The use of recursive make is pervasive in legacy projects. Automake supports non-recursive builds, but it's not a very widely used approach.

About the learning curve, there are two very good sources to learn from:

• The website here
• The book here

The first source will get you up and running faster. The book is a more in-depth discussion.

From Scons, waf and tup, Scons and tup are more like make. Waf is more like CMake and the autotools. I tried waf instead of cmake at first. I think it is overengineered in the sense that it has a full OOP API. The scripts didn't look short at all and it was really confusing for me the working directory stuff and related things. At the end, I found that autotools and CMake are a better choice. My favourite from these 3 build systems is tup.

Tup

Pros

• Really correct.
• Insanely fast. You should try it to believe it.
• The scripting language relies on a very easy idea that can be understood in 10 minutes.

Cons

• It does not have a full-featured config framework.
• I couldn't find the way to make targets such as doc, since they generate files I don't know of and they must be listed in the output before being generated, or at least, that's my conclusion for now. This was a really annoying limitation, if it is, since I am not sure.

All in all, the only things I am considering right now for new projects is are Cmake and Meson. When I have a chance I will try tup also, but it lacks the config framework, which means that it makes things more complex when you need all of that stuff. On the other hand, it is really fast.