Although rust can dynamically link with C/C++ libraries, it cannot dynamically link with other Rust libraries. Instead, they are statically compiled into the binary itself.
But the GPL interacts differently with static linking than with dynamic. If you make a static binary with a GPL library or GPL code, your program must be GPL. If you dynamically link a GPL library, you’re program doesn’t have to be GPL. It’s partially because of this, that the vast majority of Rust programs and libraries are permissively licensed — to make a GPL licensed rust library would mean it would see much less use than a GPL licensed C library, because corporations wouldn’t be able to extend proprietary code off of it — not that I care about that, but the library makers often do.
Hmmmm. But it seems that people really like to compile static rust binaries, however, due to their portability across Linux distros.
EDIT2: Upon further research it seems that Rust’s dynamic linking implementation lacks a “stable ABI” as compared to other languages such as Swift or C. So I guess we are back to “it is a language issue”. Well thankfully this seems easier to fix than “Yeah Rust doesn’t support dynamic linking at all.”
Edit3: Nvm, I’m very, very wrong. The GPL does require programs using GPL libraries, even dynamically linked, be GPL. It’s the LGPL that doesn’t.
As long as two binaries are compiled with the same version of the Rust compiler, they are ABI compatible.
Even if the compiler version differs, I’ve found that changes to the ABI are fairly uncommon.
Furthermore, anything exposed through the C ABI is stable, so the problem can be circumvented if needed.
It’s not the most ergonomic solution, admittedly, but with some compromises dynamic linking is perfectly feasible.
It actually is a language issue.
Although rust can dynamically link with C/C++ libraries, it cannot dynamically link with other Rust libraries. Instead, they are statically compiled into the binary itself.
But the GPL interacts differently with static linking than with dynamic. If you make a static binary with a GPL library or GPL code, your program must be GPL. If you dynamically link a GPL library, you’re program doesn’t have to be GPL. It’s partially because of this, that the vast majority of Rust programs and libraries are permissively licensed — to make a GPL licensed rust library would mean it would see much less use than a GPL licensed C library, because corporations wouldn’t be able to extend proprietary code off of it — not that I care about that, but the library makers often do.
https://en.wikipedia.org/wiki/GNU_General_Public_License#Libraries — it’s complicated.
EDIT: Nvm I’m wrong. Rust does allow dynamic linking
Hmmmm. But it seems that people really like to compile static rust binaries, however, due to their portability across Linux distros.
EDIT2: Upon further research it seems that Rust’s dynamic linking implementation lacks a “stable ABI” as compared to other languages such as Swift or C. So I guess we are back to “it is a language issue”. Well thankfully this seems easier to fix than “Yeah Rust doesn’t support dynamic linking at all.”
Edit3: Nvm, I’m very, very wrong. The GPL does require programs using GPL libraries, even dynamically linked, be GPL. It’s the LGPL that doesn’t.
As long as two binaries are compiled with the same version of the Rust compiler, they are ABI compatible. Even if the compiler version differs, I’ve found that changes to the ABI are fairly uncommon. Furthermore, anything exposed through the C ABI is stable, so the problem can be circumvented if needed. It’s not the most ergonomic solution, admittedly, but with some compromises dynamic linking is perfectly feasible.