Is libsqlite3-sys really needed?

[CGenie]

Hello,

I know proj requires sqlite3 for some of it's functionality. However, I'm not sure it exposes any of that to the external world.

My question is: do we really need this:

https://github.com/georust/proj/blob/main/proj-sys/Cargo.toml#L15

The extern crate is defined only under the bundled_build cfg:

https://github.com/georust/proj/blob/main/proj-sys/src/lib.rs#L31

and I think that cfg is disabled by default.

The reason I'm asking is that I want to have both proj and rusqlite and I get

Using proj = 0.29 (I know 0.30 is most recent, but because of some nix stuff, I'm forced to use 0.29) and rusqlite=0.36.0, I get this error:

error: failed to select a version for `libsqlite3-sys`.
    ... required by package `proj-sys v0.25.0`
    ... which satisfies dependency `proj-sys = "^0.25.0"` of package `proj v0.29.0`
    ... which satisfies dependency `proj = "^0.29.0"` of package `binaries v0.1.0 (xxx/binaries)`
versions that meet the requirements `>=0.28, <0.31` are: 0.30.1, 0.30.0, 0.29.0, 0.28.0

package `libsqlite3-sys` links to the native library `sqlite3`, but it conflicts with a previous package which links to `sqlite3` as well:
package `libsqlite3-sys v0.34.0`
    ... which satisfies dependency `libsqlite3-sys = "^0.34.0"` of package `rusqlite v0.36.0`
    ... which satisfies dependency `rusqlite = "^0.36.0"` of package `xxx v0.1.0 (/xxx)`
    ... which satisfies path dependency `xxx` (locked to 0.1.0) of package `binaries v0.1.0 (xxx/binaries)`
Only one package in the dependency graph may specify the same links value. This helps ensure that only one copy of a native library is linked in the final binary. Try to adjust your dependencies so that only one package uses the `links = "sqlite3"` value. For more information, see https://doc.rust-lang.org/cargo/reference/resolver.html#links.

failed to select a version for `libsqlite3-sys` which could resolve this conflict

[urschrei]

but because of some nix stuff

That would seem to be the source of the issue. I don't think we'll be trying to make changes because nix can't use 0.30.0

[CGenie]

When I switch to 0.30, I still can't compile this with rusqlite = 0.36.0 because of that libsqlite3-sys error.

This is a cargo error, nix is just an env that I use to install system libs. I suppose I had the same error if I just used system libs, without nix.

[weiznich]

See #190 for previous discussions why the dependency to libsqlite3-sys exists. The short version is that this gives you a much better detection and control around how libsqlite3 should be linked to your binary.