Merge pull request #28 from nixops4/better-conditional-compilation-and-maintenance

Better conditional compilation and some dev maintenance

dev/flake-module.nix

@@ -81,6 +81,9 @@
           config.packages.nix
         ];
         nativeBuildInputs = [
+          pkgs.pre-commit
+          config.treefmt.build.wrapper
+
           pkgs.rust-analyzer
           pkgs.nixfmt-rfc-style
           pkgs.rustfmt
@@ -96,7 +99,6 @@
         ];
         shellHook = ''
           ${config.pre-commit.installationScript}
-          source ${../bindgen-gcc.sh}
           echo 1>&2 "Welcome to the development shell!"
         '';
         # rust-analyzer needs a NIX_PATH for some reason

flake.lock

@@ -27,11 +27,11 @@
         "pyproject-nix": "pyproject-nix"
       },
       "locked": {
-        "lastModified": 1764021028,
+        "lastModified": 1765228272,
-        "narHash": "sha256-4OlkDA0yJyqt5iTX9NqtHNghvkWNzYqmtX7FxDmEXt4=",
+        "narHash": "sha256-duTz4J4NP1edl/ZBdwZPduPM8j6g0yzjb8YH91T9vU0=",
         "owner": "nix-community",
         "repo": "dream2nix",
-        "rev": "ee20942e4524d3458a91108716c847a2d4299d2e",
+        "rev": "83c430ce6b6aedf149c5259f066bfff808722dbd",
         "type": "github"
       },
       "original": {
@@ -170,11 +170,11 @@
         "nixpkgs-regression": "nixpkgs-regression"
       },
       "locked": {
-        "lastModified": 1764979397,
+        "lastModified": 1765241125,
-        "narHash": "sha256-oMSKV0NFQpfwYQ4wcIIDuH+0AwCQl+bYRgPznx38i8k=",
+        "narHash": "sha256-/Rr90FVpncaSWprG6+4t5VXHgDKDvFitzJPpdZgo+8I=",
         "owner": "NixOS",
         "repo": "nix",
-        "rev": "525755dadc153c68e5ada8d287ab19af26383fff",
+        "rev": "7448aedd74e28174bfa33aad0d148c0070c86dfb",
         "type": "github"
       },
       "original": {
@@ -196,11 +196,11 @@
         "treefmt": "treefmt"
       },
       "locked": {
-        "lastModified": 1765001919,
+        "lastModified": 1765261286,
-        "narHash": "sha256-S5k0HAxjq2sbf5BC5DOly66joE08HfiyEJD8v2U3yLc=",
+        "narHash": "sha256-Ll29VFrT+VpnP4HG5LiL33IXuiz6cF2WfTwXONwMj7E=",
         "owner": "yusdacra",
         "repo": "nix-cargo-integration",
-        "rev": "0feff946314851edc88b9c783ad7d2dccd49abcc",
+        "rev": "92639295bbe953e4c8c32cbffa32dcb0a441118b",
         "type": "github"
       },
       "original": {
@@ -211,11 +211,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1764950072,
+        "lastModified": 1765186076,
-        "narHash": "sha256-BmPWzogsG2GsXZtlT+MTcAWeDK5hkbGRZTeZNW42fwA=",
+        "narHash": "sha256-hM20uyap1a0M9d344I692r+ik4gTMyj60cQWO+hAYP8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f61125a668a320878494449750330ca58b78c557",
+        "rev": "addf7cf5f383a3101ecfba091b98d0a1263dc9b8",
         "type": "github"
       },
       "original": {
@@ -355,11 +355,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1764988672,
+        "lastModified": 1765248027,
-        "narHash": "sha256-FIJtt3Zil89/hLy9i7f0R2xXcJDPc3CeqiiCLfsFV0Y=",
+        "narHash": "sha256-ngar+yP06x3+2k2Iey29uU0DWx5ur06h3iPBQXlU+yI=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "086fd19a68e80fcc8a298e9df4674982e4c498a6",
+        "rev": "7b50ad68415ae5be7ee4cc68fa570c420741b644",
         "type": "github"
       },
       "original": {

nix-bindings-store/Cargo.toml

@@ -20,3 +20,5 @@ tempfile = "3.10"
 
 [build-dependencies]
 pkg-config = "0.3"
+# Needed for version parsing in build.rs
+nix-bindings-util = { path = "../nix-bindings-util" }

nix-bindings-store/build.rs

@@ -1,39 +1,6 @@
+use nix_bindings_util::nix_version::emit_version_cfg;
+
 fn main() {
-    // Get nix version
     let nix_version = pkg_config::probe_library("nix-store-c").unwrap().version;
-
+    emit_version_cfg(&nix_version, &["2.26", "2.33.0pre", "2.33"]);
-    // Generate version flags
-    // Unfortunately, Rust doesn't give us a "greater than" operator in conditional
-    // compilation, so we pre-evaluate the version comparisons here, making use
-    // of the multi-valued nature of Rust cfgs.
-    let relevant_versions = vec!["2.26", "2.33"];
-    let versions = relevant_versions
-        .iter()
-        .map(|v| format!("\"{}\"", v))
-        .collect::<Vec<_>>()
-        .join(",");
-
-    // Declare the known versions, so that Rust can warn about unknown versions
-    // that aren't part of `relevant_versions` yet - feel free to add entries.
-    println!(
-        "cargo:rustc-check-cfg=cfg(nix_at_least,values({}))",
-        versions
-    );
-
-    let nix_version = nix_version.split('.').collect::<Vec<&str>>();
-    let nix_version = (
-        nix_version[0].parse::<u32>().unwrap(),
-        nix_version[1].parse::<u32>().unwrap(),
-    );
-
-    for version_str in relevant_versions {
-        let version = version_str.split('.').collect::<Vec<&str>>();
-        let version = (
-            version[0].parse::<u32>().unwrap(),
-            version[1].parse::<u32>().unwrap(),
-        );
-        if nix_version >= version {
-            println!("cargo:rustc-cfg=nix_at_least=\"{}\"", version_str);
-        }
-    }
 }

nix-bindings-store/src/derivation.rs

@@ -1,4 +1,4 @@
-#![cfg(nix_at_least = "2.33")]
+#![cfg(nix_at_least = "2.33.0pre")]
 
 use nix_bindings_bindgen_raw as raw;
 use std::ptr::NonNull;

nix-bindings-store/src/store.rs

@@ -6,7 +6,7 @@ use nix_bindings_util::string_return::{
     callback_get_result_string, callback_get_result_string_data,
 };
 use nix_bindings_util::{check_call, result_string_init};
-#[cfg(nix_at_least = "2.33")]
+#[cfg(nix_at_least = "2.33.0pre")]
 use std::collections::BTreeMap;
 use std::collections::HashMap;
 use std::ffi::{c_char, CString};
@@ -14,7 +14,7 @@ use std::ptr::null_mut;
 use std::ptr::NonNull;
 use std::sync::{Arc, Mutex, Weak};
 
-#[cfg(nix_at_least = "2.33")]
+#[cfg(nix_at_least = "2.33.0pre")]
 use crate::derivation::Derivation;
 use crate::path::StorePath;
 
@@ -71,7 +71,7 @@ lazy_static! {
     static ref STORE_CACHE: Arc<Mutex<StoreCacheMap>> = Arc::new(Mutex::new(HashMap::new()));
 }
 
-#[cfg(nix_at_least = "2.33")]
+#[cfg(nix_at_least = "2.33.0pre")]
 unsafe extern "C" fn callback_get_result_store_path_set(
     _context: *mut raw::c_context,
     user_data: *mut std::os::raw::c_void,
@@ -88,7 +88,7 @@ unsafe extern "C" fn callback_get_result_store_path_set(
     ret.push(store_path);
 }
 
-#[cfg(nix_at_least = "2.33")]
+#[cfg(nix_at_least = "2.33.0pre")]
 fn callback_get_result_store_path_set_data(vec: &mut Vec<StorePath>) -> *mut std::os::raw::c_void {
     vec as *mut Vec<StorePath> as *mut std::os::raw::c_void
 }
@@ -274,7 +274,7 @@ impl Store {
     /// # Returns
     /// A [`Derivation`] object if parsing succeeds, or an error if the JSON is invalid
     /// or malformed.
-    #[cfg(nix_at_least = "2.33")]
+    #[cfg(nix_at_least = "2.33.0pre")]
     #[doc(alias = "nix_derivation_from_json")]
     pub fn derivation_from_json(&mut self, json: &str) -> Result<Derivation> {
         let json_cstr = CString::new(json)?;
@@ -302,7 +302,7 @@ impl Store {
     ///
     /// # Returns
     /// The store path of the derivation (ending in `.drv`).
-    #[cfg(nix_at_least = "2.33")]
+    #[cfg(nix_at_least = "2.33.0pre")]
     #[doc(alias = "nix_add_derivation")]
     pub fn add_derivation(&mut self, drv: &Derivation) -> Result<StorePath> {
         unsafe {
@@ -331,7 +331,7 @@ impl Store {
     /// # Returns
     /// A [`BTreeMap`] mapping output names (e.g., "out", "dev", "doc") to their store paths.
     /// The map is ordered alphabetically by output name for deterministic iteration.
-    #[cfg(nix_at_least = "2.33")]
+    #[cfg(nix_at_least = "2.33.0pre")]
     #[doc(alias = "nix_store_realise")]
     pub fn realise(&mut self, path: &StorePath) -> Result<BTreeMap<String, StorePath>> {
         let mut outputs = BTreeMap::new();
@@ -388,7 +388,7 @@ impl Store {
     ///
     /// # Returns
     /// A vector of store paths in the closure, in no particular order.
-    #[cfg(nix_at_least = "2.33")]
+    #[cfg(nix_at_least = "2.33.0pre")]
     #[doc(alias = "nix_store_get_fs_closure")]
     pub fn get_fs_closure(
         &mut self,
@@ -544,6 +544,7 @@ mod tests {
         assert!(weak.inner.upgrade().is_none());
     }
 
+    #[cfg(nix_at_least = "2.33.0pre")]
     fn create_temp_store() -> (Store, tempfile::TempDir) {
         let temp_dir = tempfile::tempdir().unwrap();
 
@@ -616,7 +617,7 @@ mod tests {
     }
 
     #[test]
-    #[cfg(nix_at_least = "2.33")]
+    #[cfg(nix_at_least = "2.33.0pre")]
     fn derivation_from_invalid_json() {
         let (mut store, temp_dir) = create_temp_store();
         let result = store.derivation_from_json("not valid json");

nix-bindings-util/src/lib.rs

@@ -2,3 +2,4 @@ pub mod context;
 pub mod settings;
 #[macro_use]
 pub mod string_return;
+pub mod nix_version;

nix-bindings-util/src/nix_version.rs

@@ -0,0 +1,101 @@
+//! Nix version parsing and conditional compilation support.
+
+/// Emit [`cargo:rustc-cfg`] directives for Nix version-based conditional compilation.
+///
+/// Call from build.rs with the Nix version and desired version gates.
+///
+/// [`cargo:rustc-cfg`]: https://doc.rust-lang.org/cargo/reference/build-scripts.html#rustc-cfg
+///
+/// # Example
+///
+/// ```
+/// use nix_bindings_util::nix_version::emit_version_cfg;
+/// # // Stub pkg_config so that we can render a full usage example
+/// # mod pkg_config { pub fn probe_library(_: &str) -> Result<Library, ()> { Ok(Library { version: "2.33.0pre".into() }) }
+/// #   pub struct Library { pub version: String } }
+///
+/// let nix_version = pkg_config::probe_library("nix-store-c").unwrap().version;
+/// emit_version_cfg(&nix_version, &["2.26", "2.33.0pre", "2.33"]);
+/// ```
+///
+/// Emits `nix_at_least="2.26"` and `nix_at_least="2.33.0pre"` for version 2.33.0pre,
+/// usable as `#[cfg(nix_at_least = "2.26")]`.
+pub fn emit_version_cfg(nix_version: &str, relevant_versions: &[&str]) {
+    // Declare the known versions for cargo check-cfg
+    let versions = relevant_versions
+        .iter()
+        .map(|v| format!("\"{}\"", v))
+        .collect::<Vec<_>>()
+        .join(",");
+
+    println!(
+        "cargo:rustc-check-cfg=cfg(nix_at_least,values({}))",
+        versions
+    );
+
+    let nix_version = parse_version(nix_version);
+
+    for version_str in relevant_versions {
+        let version = parse_version(version_str);
+        if nix_version >= version {
+            println!("cargo:rustc-cfg=nix_at_least=\"{}\"", version_str);
+        }
+    }
+}
+
+/// Parse a Nix version string into a comparable tuple `(major, minor, patch)`.
+///
+/// Pre-release versions (containing `"pre"`) get patch = -1, sorting before stable releases.
+/// Omitted patch defaults to 0.
+///
+/// # Examples
+///
+/// ```
+/// use nix_bindings_util::nix_version::parse_version;
+///
+/// assert_eq!(parse_version("2.26"), (2, 26, 0));
+/// assert_eq!(parse_version("2.33.0pre"), (2, 33, -1));
+/// assert_eq!(parse_version("2.33"), (2, 33, 0));
+/// assert_eq!(parse_version("2.33.1"), (2, 33, 1));
+///
+/// // Pre-release versions sort before stable
+/// assert!(parse_version("2.33.0pre") < parse_version("2.33"));
+/// ```
+pub fn parse_version(version_str: &str) -> (u32, u32, i32) {
+    let parts = version_str.split('.').collect::<Vec<&str>>();
+    let major = parts[0].parse::<u32>().unwrap();
+    let minor = parts[1].parse::<u32>().unwrap();
+    let patch = if parts.get(2).map_or(false, |s| s.contains("pre")) {
+        -1i32
+    } else {
+        parts
+            .get(2)
+            .and_then(|s| s.parse::<i32>().ok())
+            .unwrap_or(0)
+    };
+    (major, minor, patch)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_version() {
+        assert_eq!(parse_version("2.26"), (2, 26, 0));
+        assert_eq!(parse_version("2.33.0pre"), (2, 33, -1));
+        assert_eq!(parse_version("2.33"), (2, 33, 0));
+        assert_eq!(parse_version("2.33.1"), (2, 33, 1));
+    }
+
+    #[test]
+    fn test_version_ordering() {
+        // Pre-release versions should sort before stable
+        assert!(parse_version("2.33.0pre") < parse_version("2.33"));
+        assert!(parse_version("2.33.0pre") < parse_version("2.33.0"));
+
+        // Normal version ordering
+        assert!(parse_version("2.26") < parse_version("2.33"));
+        assert!(parse_version("2.33") < parse_version("2.33.1"));
+    }
+}