Comment by tbirdz | Hacker News Reader

Comment by tbirdz | Hacker News Reader

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I really disagree with you on autotools, that has been a big problem for me when cross-compiling. Configure often detects features by compiling a binary and executing it, which can be a problem when you're cross compiling, since the generated target can't be executed on your native cpu. Most software build systems don't even take cross building into account at all, since they just copied someone elses' broken autoconf and automake source that only works on native builds so you have to work around a lot of issues.

Even "good" software packages written by people who understand autotools like glib have issues. Just look at the official glib cross compiling instructions: https://developer.gnome.org/glib/stable/glib-cross-compiling... The "correct" way to cross compile it is to figure out all the autoconfigured values yourself, and write them into the configure cache.

Personally, I have had the least trouble with plain Makefile based packages. Yes you often have to reach into the Makefile's guts and modify it to make a working cross build, and you'll have to set the rpath manually, and install the files yourself, but at least it's easier than having to modify an autotools based build.

Autotools "just works", and when it doesn't it's very hard to fix. Makefiles don't "just work", but it's much easier to fix them yourself.

"Configure often detects features by compiling a binary and executing it" — I am not sure, where this impression comes from. Autotools as whole have excellent cross-compilation support. Autoconf has feature-detection routines, checking for presence of headers, exported symbols and pkg-config files. None of those trigger "execute the binary" part when cross-compiling. In addition, custom-written host-side checks can easily be skipped when cross-compiling (either by code of check itself or by user via environent-variable overrides). Do you you know of any build system, that handles this better?

Cmake and several other buildsystems either don't support cross-compilation at all (because their primary audience is Windows) or use pkg-config only. Few others are nightmarish parody of autotools with much worse support. Most don't have ounce of autotools features.

I know many projects, that offer horrible autotools "support": for example, glib2 autotools scripts can't be cross-compiled to Android without ample application of hacks. But those issues are caused by incompetence and lack of testing, not some innate fault of Autotools. When such projects migrate to something else, their cross-compilation process becomes WORSE.

The impression comes from having to deal with multiple configure sciripts that do that very thing.

The capabilities may be there, but in my experience many if not most projects do not use those capabilities. Most autotools based projects I've had to cross build are made by people without a great understanding of autotools internals and capabilities, so they often end up copy pasting things blindly from other projects until they get their native build working. Advanced build system stuff like cross building is not even considered.

These builds end up trying to execute a binary to do feature tests, or compile a program and use that to generate code, or do any number of things that break when cross building.

Would things be worse without autotools? Maybe so. In my personal experience projects using a simple Makefile were much easier to cross build and package than ones using autotools, but that's probably confounded by projects using a Makefile being simpler overall.

To clarify for anyone who doubts autotools has problems - it is true that the documentation mentions cross compiling options, but it appears that the vast majority of tests in use today do not actually use these values (host/target arch, etc).

Some users recommend compiling with qemu-user to avoid fixing the tests, but besides being very slow, that methodology will still generate garbage. What is the point of running feature detection code on a desktop that will be used to configure code compiled to run on e.g. a small ARM system?

The fix is to explicitly set configuration parameters or, even better, to detect features at runtime. However if you try to contact any given project using autotools to help solve these configuration problems you will likely receive "that's not our problem" and no help from the maintainers.

Autotools is in practice less work for me than alternatives, at least while using a FOSS operating system. On Windows CMake is very well developed but handling dependencies is always a chore.

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