Consider using "lib" prefix for Cygwin cdylib?

[500-internal-server-error]

Currently, despite considered a Unix, Cygwin inherits Windows' lack of lib prefix for cdylibs:

$ echo | rustc --crate-type cdylib - # using rustc for simplicity, but cargo projects behave the same
$ ls
librust_out.dll.a rust_out.dll

Whereas all other Unix targets produce lib + name + .so / .dylib. This makes porting applications more hassle than it needs to be IMO.

I think Windows GNU targets should also behave the same, but I imagine that is going to be a lot more breakage, potentially more than it's worth, so I'll limit the request to Cygwin, but opinions welcome.

FWIW, CMake also produces libraries with the lib prefix.

Meta

$ rustc --version --verbose
rustc 1.91.0 (f8297e351 2025-10-28) (Rev4, Built by MSYS2 project)
binary: rustc
commit-hash: f8297e351a40c1439a467bbbb6879088047f50b3
commit-date: 2025-10-28
host: x86_64-pc-cygwin
release: 1.91.0
LLVM version: 21.1.1

(backtrace N/A)

[mati865]

It cannot be easily changed because that would be a breaking change to public API:

rust/library/std/src/sys/env_consts.rs

Line 41 in 7a72c54

pub mod os {

Cygwin is not that popular yet so it might be acceptable, but that is not an easy decision to make. windows-gnu is out of the question.

[500-internal-server-error]

but that is not an easy decision to make.

Is there a formal process to initiate the discussion? I'm not very familiar with Rust project internal workings.

[Noratrieb]

For cygwin the process is just asking the target maintainer, @Berrysoft, if they agree it's good, I'm sure it would be acceptable to change it

[Berrysoft]

Thanks for the suggestion, but I'm a little hesitate. The dll names of Cygwin are prefixed with cyg, and those of MSYS2 are prefixed with msys-. None of them are prefixed with lib actually. As they are different on Cygwin and MSYS2, and the cygwin target is designed for both, I left the prefix as empty.

BTW the dll names of MinGW shipped by MSYS2 are prefixed with lib. Maybe that's why Cygwin chooses a different prefix.

I think there's a way to specify the dll name, through Cargo.toml? It would be good to have the dll name prefixed, but I would like to leave the chance to select a different prefix.

[500-internal-server-error]

The dll names of Cygwin are prefixed with cyg, and those of MSYS2 are prefixed with msys-. None of them are prefixed with lib actually. As they are different on Cygwin and MSYS2, and the cygwin target is designed for both, I left the prefix as empty.

Now that I think about it, even if the prefix does get added, I might need to fiddle around with build scripts anyway...

I think there's a way to specify the dll name, through Cargo.toml? It would be good to have the dll name prefixed, but I would like to leave the chance to select a different prefix.

Last I checked, they were simply proposals and discussions, but I don't think there's anything implemented, short of prefixing the crate name itself. But that just moves the problem elsewhere.

[Noratrieb]

There is no way to configure it, no. You need to manually rename the file afterwards.