Cargo fails to find minimal satisfiable set of dependencies #4902
Description
I'm currently experiencing an issue where Cargo selects two different versions of a -sys crate when one version of the -sys crate is enough to satisfy dependency constraints. In my particular case, my Cargo.toml [dependencies] look like:
[dependencies]
rusqlite = "0.13"
diesel = { version = "1.0", features = ["sqlite"] }Both crates depend on libsqlite3-sys. Here's what they list in their dependency section:
// diesel 1.0
libsqlite3-sys = { version = ">=0.8.0, <0.10.0", optional = true, features = ["min_sqlite_version_3_7_16"] }
// rusqlite 0.13
[dependencies.libsqlite3-sys]
version = "0.9"
Here's what Cargo decides for these constraints:
[dependencies]
├── diesel v1.0.0
│ └── libsqlite3-sys v0.8.1
└── rusqlite v0.13.0
└─── libsqlite3-sys v0.9.1
Or, as seen from Cargo.lock:
[[package]]
name = "diesel"
version = "1.0.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"libsqlite3-sys 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
name = "libsqlite3-sys"
version = "0.8.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
"vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
name = "libsqlite3-sys"
version = "0.9.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
"vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
name = "rusqlite"
version = "0.13.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
dependencies = [
"libsqlite3-sys 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
]This is a suboptimal choice. What's worse, because this is a -sys dependency, this causes compilation to fail needlessly. The optimal, correct decision is to choose libsqlite3-sys 0.9.1 for both dependencies.