Split monolithic raw crates into sys crates

Creating a crate for bwd-gc highlights the fact that it would be nice to
fix 2!

The file blocklist is a lost less unmaintainable then the more
fine-grained one we had before.

Fix #9

nix-bindings-util-sys/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nix-bindings-util-sys"
-version = "0.1.1"
+version = "0.2.0"
 edition = "2021"
 build = "build.rs"
 license = "LGPL-2.1"
@@ -10,6 +10,8 @@ repository = "https://github.com/nixops4/nix-bindings-rust"
 [lib]
 path = "src/lib.rs"
 
+[dependencies]
+
 [build-dependencies]
 bindgen = "0.69"
 pkg-config = "0.3"

nix-bindings-util-sys/README.md

@@ -1,12 +1,5 @@
 # nix-bindings-util-sys
 
-This crate contains generated bindings for the Nix C API.
+This crate contains generated bindings for the Nix C API (`nix-util-c`).
 **You should not have to use this crate directly,** and so you should probably not add it to your dependencies.
-Instead, use the `nix-bindings-util`, `nix-bindings-store` and `nix-bindings-expr` crates, which _should_ be sufficient.
-
-## Design
-
-Rust bindgen currently does not allow "layered" libraries to be split into separate crates.
-For example, the expr crate would have all-new types that are distinct and incompatible with the store crate.
-
-Ideally bindgen will support reusing already generated modules, and we could move the code generation into the appropriate crates, so that the system dependencies of each crate become accurate.
+Instead, use the `nix-bindings-util` crate, which _should_ be sufficient.

nix-bindings-util-sys/build.rs

@@ -11,12 +11,12 @@ impl bindgen::callbacks::ParseCallbacks for StripNixPrefix {
 
 fn main() {
     // Tell cargo to invalidate the built crate whenever the wrapper changes
-    println!("cargo:rerun-if-changed=include/nix-c-raw.h");
-    println!("cargo:rustc-link-lib=nixflake");
+    println!("cargo:rerun-if-changed=include/nix-c-util.h");
+    println!("cargo:rustc-link-lib=nixutil");
 
     // https://rust-lang.github.io/rust-bindgen/library-usage.html
     let bindings = bindgen::Builder::default()
-        .header("include/nix-c-raw.h")
+        .header("include/nix-c-util.h")
         // Find the includes
         .clang_args(c_headers())
         // Tell cargo to invalidate the built crate whenever any of the
@@ -38,15 +38,7 @@ fn main() {
 fn c_headers() -> Vec<String> {
     let mut args = Vec::new();
     // args.push("-isystem".to_string());
-    for path in pkg_config::probe_library("nix-flake-c")
-        .unwrap()
-        .include_paths
-        .iter()
-    {
-        args.push(format!("-I{}", path.to_str().unwrap()));
-    }
-
-    for path in pkg_config::probe_library("bdw-gc")
+    for path in pkg_config::probe_library("nix-util-c")
         .unwrap()
         .include_paths
         .iter()

nix-bindings-util-sys/include/nix-c-raw.h

@@ -1,7 +0,0 @@
-#include <nix_api_util.h>
-#include <nix_api_store.h>
-#define GC_THREADS
-#include <gc/gc.h>
-#include <nix_api_expr.h>
-#include <nix_api_value.h>
-#include <nix_api_flake.h>

nix-bindings-util-sys/include/nix-c-util.h

@@ -0,0 +1 @@
+#include <nix_api_util.h>