Should ruby-build check for dependencies?

[henrebotha]

I had to run the "build failure due to libyaml" gauntlet earlier. It was quite obtuse: I was using mise, which calls out to ruby-build, which simply gives a cryptic error about "psych". No part of the error message made it clear to me that I was missing dependencies. In my mind, tools that aid in building and installing things exist in part so that I don't have to manually check and verify and install dependencies before I proceed.

The README helpfully notes:

ruby-build mostly does not verify that system dependencies are present before downloading and attempting to compile Ruby from source. Please ensure that all requisite libraries such as build tools and development headers are already present on your system.

My question is: Why not? Surely the experience of installing Ruby via ruby-build would be greatly improved if the tool first checked for such dependencies before attempting to proceed with the build. A great many support tickets downstream of ruby-build would be prevented; there are at least 4 discussions on mise where baffled users can't understand why Ruby is failing to install, a direct consequence of ruby-build neither checking for deps first nor making it clear why the failure occurred (at a human-readable level; "there was a problem with psych" is not as clear as "you are missing required dependencies, please see link/to/docs/deps").

I'm trying to think of some counter-arguments here, but I'm struggling lol. Clearly that means my argument is waterproof, and is not a sign of insufficient understanding on my part.

[mislav]

My question is: Why not? Surely the experience of installing Ruby via ruby-build would be greatly improved if the tool first checked for such dependencies before attempting to proceed with the build.

That's a good question! The short answer is: Ruby has a quite complex build system (which I'm not overly familiar with) that has been growing over the last ~20 years, supports a wide range of platforms, and keeps being tweaked with each new Ruby version. If ruby-build attempts to detect system dependencies, then we'd have to replicate parts of Ruby's build system. Worse yet, if we fail to detect a system dependency being installed, but Ruby itself would have discovered it, then we sabotage what would otherwise be a successful build.

However, I absolutely agree with you that it's a shame that a lot of users seem to be first attempting to use ruby-build, then run into cryptic build failures such as the ill-named "psych", then need to end up in our Issues/Discussions section or on the wiki: https://github.com/rbenv/ruby-build/wiki#suggested-build-environment. A better user experience would have helped the user without them having to search the Web for straightforward solutions.

Should ruby-build scan build logs for typical failures like failing to build the "openssl" or "psych" extensions and recommend solutions so that the user doesn't have to search?