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Add [package.metadata.system-deps] to mlua-sys/Cargo.toml #660

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Add [package.metadata.system-deps] to mlua-sys/Cargo.toml #660

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e02ec3e
Add [package.metadata.system-deps] to mlua-sys/Cargo.toml
slowsage Nov 26, 2025
24269b6
Migrate to `system-deps` for mlua-sys
slowsage Nov 26, 2025
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9 changes: 8 additions & 1 deletion mlua-sys/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -38,10 +38,17 @@ module = []
[build-dependencies]
cc = "1.0"
cfg-if = "1.0"
pkg-config = "0.3.17"
system-deps = "7.0"
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@alerque alerque Nov 26, 2025

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Distro packager hat on here. How exactly does the system-deps crate go about determining if the appropriate headers and sources are installed on a host system? If this isn't using pkg-config under the hood somewhere (it may be) then this feels like a regression. If it's just an ergonomic wrapper around the same tooling that's probably fine, but it it is some bespoke hand rolled detection system this would be a huge red flag.

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@slowsage slowsage Nov 26, 2025

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There are two separate changes - adding metadata for parsing by any tool (easier than going through code) and one to use the added metadata for pkg-config's probe() calls:

  1. First commit: Specifying dependencies in Cargo.toml in a way that can be parsed. This is for any bespoke tools - no code change, only metadata added to Cargo.toml. Figured the format from system-deps can be reused (as in the second commit, described below). This commit is enough for ci tools to parse and figure out which pkgs to install.
  2. Second commit: Once we specify in Cargo.toml, we might as well switch to system-deps in mlua-sys itself. Cargo.toml of system-deps crate uses pkg-config.
    It explicitly uses pkg-config under the hood here.

For my use case, the first commit is enough but system-deps can use it to call pkg-config's probe() and we can avoid repeating the same info in the code, hence the second commit.

Please let me know if I missed something.

lua-src = { version = ">= 548.1.0, < 548.2.0", optional = true }
luajit-src = { version = ">= 210.6.0, < 210.7.0", optional = true }
luau0-src = { version = "0.17.0", optional = true }

[lints.rust]
unexpected_cfgs = { level = "allow", check-cfg = ['cfg(raw_dylib)'] }

[package.metadata.system-deps]
lua54 = { name = "lua", fallback-names = ["lua5.4", "lua-5.4", "lua54"], version = ">= 5.4, < 5.5", feature = "lua54" }
lua53 = { name = "lua", fallback-names = ["lua5.3", "lua-5.3", "lua53"], version = ">= 5.3, < 5.4", feature = "lua53" }
lua52 = { name = "lua", fallback-names = ["lua5.2", "lua-5.2", "lua52"], version = ">= 5.2, < 5.3", feature = "lua52" }
lua51 = { name = "lua", fallback-names = ["lua5.1", "lua-5.1", "lua51"], version = ">= 5.1, < 5.2", feature = "lua51" }
luajit = { name = "luajit", version = ">= 2.0.4, < 2.2", feature = "luajit" }
40 changes: 3 additions & 37 deletions mlua-sys/build/find_normal.rs
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@@ -1,7 +1,6 @@
#![allow(dead_code)]

use std::env;
use std::ops::Bound;

pub fn probe_lua() {
let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
Expand Down Expand Up @@ -29,40 +28,7 @@ pub fn probe_lua() {
return;
}

// Find using `pkg-config`

#[cfg(feature = "lua54")]
let (incl_bound, excl_bound, alt_probe, ver) =
("5.4", "5.5", ["lua5.4", "lua-5.4", "lua54"], "5.4");
#[cfg(feature = "lua53")]
let (incl_bound, excl_bound, alt_probe, ver) =
("5.3", "5.4", ["lua5.3", "lua-5.3", "lua53"], "5.3");
#[cfg(feature = "lua52")]
let (incl_bound, excl_bound, alt_probe, ver) =
("5.2", "5.3", ["lua5.2", "lua-5.2", "lua52"], "5.2");
#[cfg(feature = "lua51")]
let (incl_bound, excl_bound, alt_probe, ver) =
("5.1", "5.2", ["lua5.1", "lua-5.1", "lua51"], "5.1");
#[cfg(feature = "luajit")]
let (incl_bound, excl_bound, alt_probe, ver) = ("2.0.4", "2.2", [], "JIT");

#[rustfmt::skip]
let mut lua = pkg_config::Config::new()
.range_version((Bound::Included(incl_bound), Bound::Excluded(excl_bound)))
.cargo_metadata(true)
.probe(if cfg!(feature = "luajit") { "luajit" } else { "lua" });

if lua.is_err() {
for pkg in alt_probe {
lua = pkg_config::Config::new()
.cargo_metadata(true)
.probe(pkg);

if lua.is_ok() {
break;
}
}
}

lua.unwrap_or_else(|err| panic!("cannot find Lua{ver} using `pkg-config`: {err}"));
// This reads [package.metadata.system-deps] from Cargo.toml
system_deps::Config::new().probe().unwrap();
}

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