Define a Rust ABI

[steveklabnik]

Right now, Rust has no defined ABI. That may or may not be something we want eventually.

[ranma42]

CC me

[nrc]

See #1675 for some motivation for this feature (implementing plugins, that is plugins for Rust programs, not for the compiler).

[genodeftest]

Another motivation is the ability to ship shared libraries which could be reused by multiple applications on disk (reducing bandwith usage on update, reducing disk usage) and in RAM (through shared .text pages, reducing RAM usage).

[sdroege]

It would also make Linux distributions more happy as it would allow usage of shared libraries. Which apart from memory reduction in different ways, also make handling of security issues (or otherwise important bugs) simpler. You only have to update the code in a single place and rebuild that, instead of having to fix lots of copies of the code in different versions and rebuild everything.

[Arzte]

Shared libraries can be cool provided that there is a way to work around similar libraries accomplishing something in different ways such as openssl & libressl. There could also be value with making a way to allow a switch in-between static & dynamic libraries that can be set by the person compiling the crate. (possible flag?)

[Conan-Kudo]

In my opinion, it's very hard to take Rust seriously as a replacement systems programming language if it's not possible in any reasonably sane manner to build applications linking to libraries with a safe, stable ABI.

There are a lot of good reasons for supporting shared libraries, not the least of which is building fully-featured systems for more resource constrained devices (like your average SBC or mobile device). Not having shared libraries really blows up the disk utilization in places where it's not cheap.

@jpakkane describes this really well in his blog post where he conducts an experiment to prove this problem.

[vks]

In my opinion, it's very hard to take Rust seriously as a replacement systems programming language if it's not possible in any reasonably sane manner to build applications linking to libraries with a safe, stable ABI.

Note that C++ still doesn't have a stable ABI, and it took C decades to get one.