Fix the need of staticlib target to have a build.rs customization

This entend to fix this GHC issue https://gitlab.haskell.org/ghc/ghc/-/issues/22564#note_469030

flake.nix

@@ -21,7 +21,7 @@
         };
         toolchain = (pkgs.rustChannelOf {
           rustToolchain = ./rust-toolchain;
-          sha256 = "sha256-DzNEaW724O8/B8844tt5AVHmSjSQ3cmzlU4BP90oRlY=";
+          sha256 = "sha256-Zk2rxv6vwKFkTTidgjPm6gDsseVmmljVt201H7zuDkk=";
         }).rust;
       in {
         defaultPackage = naersk'.buildPackage ./.;

src/build.rs

@@ -1,21 +1,33 @@
-//! Support to dynamic library, require in user crate a small `build.rs` script,
-//! that link to generated Rust library a filename with GHC version suffix, e.g.
-//! `libNAME-ghcVERSION.so`, `libNAME-ghcVERSION.dylib` or `NAME-ghcVERSION.dll`
-//!
-//! Version is the one of `ghc` in `$PATH`, but could be overide with
-//! `$CABAL_PACK_GHC_VERSION` env variable!
+//! Support to both static and dynamic library, require in user crate a small
+//! `build.rs` script.
 //!
 //! This build file was written with the constraint in mind of no-dependency to
 //! keep user setup simple and be easily mergeable with an existing `build.rs`
 //! automation!
 
 fn main() {
+    // Support to static library require that library name is prefixed by `C`
+    // https://gitlab.haskell.org/ghc/ghc/-/issues/22564#note_469030
     let path = format!("target/{}", std::env::var("PROFILE").unwrap());
     #[cfg(target_family = "windows")]
     let prefix = "";
     #[cfg(target_family = "unix")]
     let prefix = "lib";
     let name = env!("CARGO_PKG_NAME");
+    #[cfg(target_family = "windows")]
+    let ext = "lib";
+    #[cfg(target_family = "unix")]
+    let ext = "a";
+    let source = format!("{prefix}{name}.{ext}");
+    let target = format!("{prefix}C{name}.{ext}");
+    symlink(&path, &source, &target);
+
+    // Support to dynamic library require to generated a filename with GHC
+    // version suffix, e.g. `libNAME-ghcVERSION.so`, `libNAME-ghcVERSION.dylib`
+    // or `NAME-ghcVERSION.dll`
+    //
+    // Version is the one of `ghc` in `$PATH`, but could be overide with
+    // `$CABAL_PACK_GHC_VERSION` env variable!
     let suffix = format!(
         "-ghc{}",
         std::env::var("CABAL_PACK_GHC_VERSION")
@@ -39,12 +51,17 @@ fn main() {
     let ext = "so";
     let source = format!("{prefix}{name}.{ext}");
     let target = format!("{prefix}{name}{suffix}.{ext}");
+    symlink(&path, &source, &target);
+}
+
+fn symlink(path: &str, source: &str, target: &str) {
     if !std::path::Path::new(&format!("{path}/{target}")).exists() {
+        std::fs::create_dir_all(path).unwrap();
         std::env::set_current_dir(path).unwrap();
         std::fs::OpenOptions::new()
             .create(true)
             .write(true)
-            .open(&source)
+            .open(source)
             .unwrap();
         #[cfg(target_family = "windows")]
         std::os::windows::fs::symlink_file(source, target).unwrap();

src/cabal.rs

@@ -1,8 +1,5 @@
 /// Generate user `.cabal`, taking `--enable-nix` option into account
 pub(crate) fn generate(name: &str, module: &str, version: &str, enable_nix: bool) -> String {
-    let lib_name = name.replace('-', "_"); // When a lib is created, "-" is replaced by "_"
-    let package_name = name.replace('_', "-"); // cabal does not expect "_" for packages names
-
     let build_type = if enable_nix {
         "
 build-type:         Simple"
@@ -20,7 +17,7 @@ custom-setup
     -- `haskell.nix` tell GHC linker where to find the `libNAME.a` by setting
     -- automatically `extra-lib-dirs`:
     -- https://input-output-hk.github.io/haskell.nix/tutorials/pkg-map.html
-    extra-libraries:  {lib_name}
+    extra-libraries:  {name}
 
     -- Cross-compilation to target `x86_64-w64-mingw32-cc` thrown a lot of
     -- `undefined reference to 'X'` errors during linking stage ...
@@ -35,7 +32,7 @@ custom-setup
         format!(
             "
     -- Libraries that are bundled with the package.
-    extra-bundled-libraries: {lib_name}"
+    extra-bundled-libraries: {name}"
         )
     };
 
@@ -52,7 +49,7 @@ custom-setup
 -- documentation, see: http://haskell.org/cabal/users-guide/
 --
 -- The name of the package.
-name:               {package_name}
+name:               {module}
 
 -- The package version.
 -- See the Haskell package versioning policy (PVP) for standards

src/errors.rs

@@ -30,16 +30,13 @@ pub(crate) enum Error {
      * please back up it before re-running `cargo cabal init --overwrite` command
      */
     CabalFilesExist(String),
-    /** `build.rs` file already exist, but `crates-type = [ "cdylib" ]` target
-     *  need to generate one, please either remove this option or back up it
-     *  before re-running `cargo cabal init --overwrite` command
+    /** `build.rs` file already exist, but `cargo-cabal` need to generate one,
+     *  please back up it before re-running `cargo cabal init --overwrite` command
      */
     BuildFileExist,
     /** `flake.nix` file already exist, but `--enable-nix` option need to
      * generate one, please either remove this CLI arg or back up it before
      * re-running `cargo cabal init --overwrite` command
      */
     FlakeFileExist,
-    /// `{0}` is an invalid crate name, it should be prefixed by `C` like `C{0}`
-    InvalidCrateName(String)
 }

src/main.rs

@@ -285,7 +285,7 @@ mod errors;
 mod flake;
 mod hsbindgen;
 
-use crate::cargo::{get_crate_type, CrateType};
+use crate::cargo::{get_crate_type};
 use ansi_term::Colour;
 use clap::{arg, Parser, Subcommand};
 use errors::Error;
@@ -373,14 +373,8 @@ fn init(
         clean(name)?;
     }
 
-    // Check that crate name is prefixed by `C` ...
-    // https://gitlab.haskell.org/ghc/ghc/-/issues/22564#note_469030
-    name.starts_with('C')
-        .then_some(())
-        .ok_or_else(|| Error::InvalidCrateName(name.to_owned()))?;
-
     // Check that project have a `crate-type` target ...
-    let crate_type = get_crate_type(root).ok_or(Error::NoCargoLibTarget)?;
+    get_crate_type(root).ok_or(Error::NoCargoLibTarget)?;
 
     // Check that `cargo cabal init` have not been already run ...
     let cabal = format!("{name}.cabal");
@@ -392,11 +386,9 @@ fn init(
     .then_some(())
     .ok_or_else(|| Error::CabalFilesExist(name.to_owned()))?;
     // ... and that no existing file would conflict ...
-    if crate_type == CrateType::DynLib {
-        (!Path::new("build.rs").exists())
-            .then_some(())
-            .ok_or(Error::BuildFileExist)?;
-    }
+    (!Path::new("build.rs").exists())
+        .then_some(())
+        .ok_or(Error::BuildFileExist)?;
     if enable_nix {
         (!Path::new("flake.rs").exists())
             .then_some(())
@@ -414,11 +406,9 @@ fn init(
     fs::write("hsbindgen.toml", hsbindgen::generate(module))
         .map_err(|_| Error::FailedToWriteFile("hsbindgen.toml".to_owned()))?;
 
-    // If `crate-type = [ "cdylib" ]` then a custom `build.rs` is needed ...
-    if crate_type == CrateType::DynLib {
-        fs::write("build.rs", include_str!("build.rs"))
-            .map_err(|_| Error::FailedToWriteFile("build.rs".to_owned()))?;
-    }
+    // A custom `build.rs` is needed by both static and dynamic libraries targets ...
+    fs::write("build.rs", include_str!("build.rs"))
+        .map_err(|_| Error::FailedToWriteFile("build.rs".to_owned()))?;
 
     // `--enable-nix` CLI option generate a `flake.nix` rather than a `Setup.lhs`
     if enable_nix {