Fix nix build for c2rust

c2rust-ast-exporter/build.rs

@@ -149,8 +149,18 @@ fn build_native(llvm_info: &LLVMInfo) {
         }
     };
 
-    // Statically link against 'clangAstExporter' which requires 'tinycbor'
+    // Use a custom tinybor directory via an environment variable
+    if let Ok(tinycbor_dir) = env::var("TINYCBOR_DIR") {
+        let include_dir = Path::new(&tinycbor_dir).join("include");
+        let lib_dir = Path::new(&tinycbor_dir).join("lib");
+
+        println!("cargo:rustc-link-search=native={}", lib_dir.display());
+        println!("cargo:rerun-if-changed={}", include_dir.display());
+    }
+
     println!("cargo:rustc-link-lib=static=tinycbor");
+
+    // Statically link against 'clangAstExporter' which requires 'tinycbor'
     println!("cargo:rustc-link-lib=static=clangAstExporter");
 
     println!("cargo:rustc-link-search=native={}", llvm_lib_dir);

flake.nix

@@ -2,54 +2,69 @@
   description = "Flake for c2rust";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     utils.url = "github:numtide/flake-utils";
     fenix = {
       url = "github:nix-community/fenix";
-    };
-    oxalica = {
-      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
     };
   };
 
-  outputs = inputs@{ self, nixpkgs, utils, fenix, oxalica}:
+  outputs = inputs@{ self, nixpkgs, utils, fenix}:
     utils.lib.eachDefaultSystem (system:
-    let
-        fenixStable = fenix.packages.${system}.fromToolchainFile {
-          file = ./rust-toolchain.toml;
-          sha256 = "sha256-r/8YBFuFa4hpwgE3FnME7nQA2Uc1uqj0eCE1NWmI1u0";
-        };
+      let
+        fenixToolchain =
+          let
+            toml = with builtins; (fromTOML (readFile ./rust-toolchain.toml)).toolchain;
+          in
+            (fenix.packages.${system}.fromToolchainName {
+              name = toml.channel;
+              sha256 = "sha256-r/8YBFuFa4hpwgE3FnME7nQA2Uc1uqj0eCE1NWmI1u0";
+            })."completeToolchain";
+
         pkgs = import nixpkgs {
           inherit system;
-          overlays = [
-            (import oxalica)
-          ];
+          overlays = [ ];
           config = {
             allowUnfree = true;
           };
         };
-        in {
-          defaultPackage = self.devShell.${system};
-          devShell = pkgs.mkShell.override { } {
 
-            LIBCLANG_PATH = "${pkgs.llvmPackages_14.libclang.lib}/lib";
-            CMAKE_LLVM_DIR = "${pkgs.llvmPackages_14.libllvm.dev}/lib/cmake/llvm";
-            CMAKE_CLANG_DIR = "${pkgs.llvmPackages_14.libclang.dev}/lib/cmake/clang";
-            shellHook = ''
-              export CARGO_TARGET_DIR="$(git rev-parse --show-toplevel)/target_dirs/nix_rustc";
-            '';
-            RUST_SRC_PATH = pkgs.rustPlatform.rustLibSrc;
-            buildInputs =
+        myLLVM = pkgs.llvmPackages_18;
+        myStdenv = pkgs.clang18Stdenv;
+
+        rustPlatform = pkgs.makeRustPlatform {
+          cargo = fenixToolchain;
+          rustc = fenixToolchain;
+        };
+        env = with pkgs; {
+          LIBCLANG_PATH = "${myLLVM.libclang.lib}/lib";
+          CMAKE_LLVM_DIR = "${myLLVM.libllvm.dev}/lib/cmake/llvm";
+          CMAKE_CLANG_DIR = "${myLLVM.libclang.dev}/lib/cmake/clang";
+          LLVM_CONFIG_PATH = "${myLLVM.libllvm.dev}/bin/llvm-config";
+          CLANG_PATH = "${myLLVM.clang}/bin/clang";
+          TINYCBOR_DIR = "${pkgs.tinycbor}";
+          NIX_ENFORCE_NO_NATIVE = 0; # Enable SSE instructions.
+          # Enable nix in the c2rust test suite
+          # This flag is used to tell the test scripts to look for
+          # libraries under nix paths.
+          C2RUST_USE_NIX = 1;
+          RUST_SRC_PATH = "${fenixToolchain}/lib/rustlib/src/rust/library";
+        };
+      in rec {
+        packages = {
+          default = rustPlatform.buildRustPackage (with pkgs; env // {
+            pname = "c2rust";
+            version = "0.20.0";
+            src = ./.;
+            doCheck = false; # Can use checkFlags to disable specific tests
+
+            patches = [ ./nix-tinycbor-cmake.patch ];
+
+            nativeBuildInputs =
               with pkgs; [
-                clangStdenv.cc
-                llvmPackages_14.libclang
                 pkg-config
-                fenix.packages.${system}.rust-analyzer
-                llvmPackages_14.clang
                 cmake
-                llvmPackages_14.llvm
-                llvmPackages_14.libllvm
-                openssl
                 (python3.withPackages
                   (python-pkgs:
                     with python-pkgs;
@@ -68,9 +83,43 @@
                     ]
                   )
                 )
+                myStdenv.cc
+                myLLVM.libclang
+                myLLVM.clang
+                myLLVM.llvm
+                myLLVM.libllvm
+              ];
+
+            buildInputs =
+              with pkgs; [
+                rustPlatform.bindgenHook
+                myStdenv.cc
+                myLLVM.libclang
+                myLLVM.clang
+                myLLVM.llvm
+                myLLVM.libllvm
+                tinycbor
+                openssl
                 zlib
-                (rust-bin.fromRustupToolchainFile ./rust-toolchain.toml)
+                fenixToolchain
               ];
-          };
-    });
+
+            cargoLock = {
+              lockFile = ./Cargo.lock;
+            };
+          });
+        };
+        defaultPackage = packages.default;
+
+        devShells = {
+          # Include a fixed version of clang in the development environment for testing.
+          default = pkgs.mkShell (with pkgs; env // {
+            strictDeps = true;
+            inputsFrom = [ packages.default ];
+            buildInputs = [ ];
+          });
+        };
+
+        devShell = devShells.default;
+      });
 }