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Comment by smartmic | Hacker News Reader

First thing that comes to my mind is the best-in-class cross-UNIX compatibility. But shouldn't the question be the other way around: What can the modern tools do that autotools can't?

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The obvious: CMake compiles into either Makefiles or Visual Studio solutions, allowing for cross Linux / Windows builds.

Support for Ninja files also seems to speed up builds in my experience. (Ninja is a Makefile "assembly language", minimal features, assuming that things like CMake files compile into Ninja). Ninja is fully multithreaded and focused on speed instead of features, and it really does show.

Since ./configure is single-threaded, a substantial amount of time needs to be spent whenever you make changes to your Autoconf / Automake stuff.

CMake has a few nice things: a built in basic testing framework (just interpreting the exit codes of programs: 0 is success and anything else is test-failure). Said testing framework has been integrated into various other test frameworks (like Googletest: https://cmake.org/cmake/help/latest/module/GoogleTest.html).

Autotools actually has some built-in test framework support too. A Makefile.am can have one or more programs marked as TEST, which will run when `make check` is executed. Depending on how you set it up, Automake knows how to use the TAP protocol to collect the pass/fail from your tests.

You can also run `make distcheck` to generate a source tarball, extract/build the tarball in isolation, and run `make check` on the result. A very handy way to make sure that you've packaged everything correctly, and everything builds/tests OK when executed out-of-tree.

To those who downvoted my parent comment, what was your reasoning? Not trying to troll - I was just trying to explain a useful Autotools feature in a discussion about Autotools and CMake features.

> The obvious: CMake compiles into either Makefiles or Visual Studio solutions, allowing for cross Linux / Windows builds.

I get that this is especially attractive for some companies earning money with Windows. But how important are contributions from developers on Windows for Linux distributions and the free software community? I think that most companies which use open source libraries on Windows are unlikely to give anything back.

Also, when it comes to things like networking and server software, Windows has many important differences, and is not that relevant at all any more. Well, every project will need to figure out on its own whether supporting Windows builds is worth the time and hassle.

And good integration with conan. Dependency management is nice. Vcpkg is getting there too.

The problem with conan is that it is yet another language-specific package manager. This is especially fatal since the importance of pure C and C++ projects is shrinking in proportion, and both are more and more used in cross-language projects. And for the latter, I think a Linux distribution or a system like GNU Guix is much better suited.

Distro managers lag and are fragmented. Guix looks good. Neither support windows though If you have that need. Trying to use conan in a blended c++/rust code base hasn't been that bad, but that is because we weren't using any crate outside stdlib.

Good point. Personally, I've avoided autotools for a long time since many projects use CMake and because of its reputation as a painful thing to learn. Lately, however, I've started learning more about autotools, so was just curious as to what it's really good at.

I am absolutely the opposite. I've avoided CMake for a long time since many projects use autotools and because of its reputation as a painful thing to learn. ;)

But actually, one of the points made in the Calcote book really stuck with me: Build tools are not just about developer convenience; they're also about the user's convenience. It's more work on my end, but my users (who, admittedly, are on UNIX-likes) know to type:

  ./configure
  make

From their standpoint, it just works as expected.

Yeah, I find it really irritating when a build system doesn’t respect this interface. Really, cargo and all these other tools should have options for generating a configure script and makefile: they could be relatively minimal and just invoke cargo with the appropriate options, but it would make it much easier to build arbitrary projects from source.

This was a near magical revelation for me. I should finish that book.

It is astounding how many tools I have to install to get most tools to work. :(

It's fascinating, isn't it? Right! Users . . . :)

> From their standpoint, it just works as expected.

This is also quite important when you happen to work on larger projects with many dozens or hundreds of modules and you need to build a specific part weeks after you have been looking at them. To have to look up every time how to build something is more than a nuisance.

I never understood why there are typically two commands and not just “make”. Is this a historical accident?

I think it is simply that make is too crufty to extend. It has perma-broken behavior around space handling, which nobody dares touch [1]. But you can't replace it because it is entrenched, so Makefiles must be wrapped, by configure or CMake or whatever. And these in turn have their own cruft, so must be wrapped, by autoconf and...well someone please wrap CMake!

The C and C++ ecosystem is crying out for a new build system, but there is no mechanism to converge on one. It's bad.

1: http://savannah.gnu.org/bugs/?712

Make does what it does surprisingly well: It runs commands on files based on a description of dependencies. There is no shortage of would-be successors of make, but so far none of them has succeeded, which supports the hypothesis that "make" has hit a sweet spot.

There is one alternative to make which I think is worth mentioning, because of its simplicity, brilliance, and excellent support for correctness: it is redo, as in Apenwarrs redo:

https://redo.readthedocs.io/en/latest/

And redo works with autotools!

This is by construction and is nicely explained by the slides I linked before.

Basically, autoconf generates a makefile which will work for your architecture. It does that via a script which is called "configure", which generates that makefile. The configure script is independent of your hardware and platform and does only require a standard POSIX shell, and it generates code for the version of "make" that is present on your platform. This means that in difference to other build systems, one does not have to install (and build!) the build system for the own platform, and also that there are no compatibility problems because the configure script always matches the source code distribution.

On top of that, the "configure" script is also automatically generated, typically using two files "config.ac" and "makefile.am", via a command which is now called "autoreconf", but this normally happens only on the developer's system.

Oh yes, the reputation of the learning curve precedes it. But the book helped me get started and, as is often the case with complex things, once you've dealt with it a bit, the experience wasn't as bad as I feared.

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