Add module root as first wheel setting

crates/uv-build-backend/src/lib.rs

@@ -66,6 +66,8 @@ pub enum Error {
     Csv(#[from] csv::Error),
     #[error("Expected a Python module with an `__init__.py` at: `{}`", _0.user_display())]
     MissingModule(PathBuf),
+    #[error("Absolute module root is not allowed: `{}`", _0.display())]
+    AbsolutModuleRoot(PathBuf),
     #[error("Inconsistent metadata between prepare and build step: `{0}`")]
     InconsistentSteps(&'static str),
     #[error("Failed to write to {}", _0.user_display())]
@@ -292,11 +294,29 @@ fn write_hashed(
     })
 }
 
+/// TODO(konsti): Wire this up with actual settings and remove this struct.
+///
+/// Which files to include in the wheel
+pub struct WheelSettings {
+    /// The directory that contains the module directory, usually `src`, or an empty path when
+    /// using the flat layout over the src layout.
+    module_root: PathBuf,
+}
+
+impl Default for WheelSettings {
+    fn default() -> Self {
+        Self {
+            module_root: PathBuf::from("src"),
+        }
+    }
+}
+
 /// Build a wheel from the source tree and place it in the output directory.
 pub fn build_wheel(
     source_tree: &Path,
     wheel_dir: &Path,
     metadata_directory: Option<&Path>,
+    wheel_settings: WheelSettings,
     uv_version: &str,
 ) -> Result<WheelFilename, Error> {
     let contents = fs_err::read_to_string(source_tree.join("pyproject.toml"))?;
@@ -319,7 +339,10 @@ pub fn build_wheel(
     let mut wheel_writer = ZipDirectoryWriter::new_wheel(File::create(&wheel_path)?);
 
     debug!("Adding content files to {}", wheel_path.user_display());
-    let strip_root = source_tree.join("src");
+    if wheel_settings.module_root.is_absolute() {
+        return Err(Error::AbsolutModuleRoot(wheel_settings.module_root));
+    }
+    let strip_root = source_tree.join(wheel_settings.module_root);
     let module_root = strip_root.join(pyproject_toml.name().as_dist_info_name().as_ref());
     if !module_root.join("__init__.py").is_file() {
         return Err(Error::MissingModule(module_root));
@@ -337,6 +360,9 @@ pub fn build_wheel(
         let relative_path_str = relative_path
             .to_str()
             .ok_or_else(|| Error::NotUtf8Path(relative_path.to_path_buf()))?;
+
+        debug!("Adding to wheel: `{relative_path_str}`");
+
         if entry.file_type().is_dir() {
             wheel_writer.write_directory(relative_path_str)?;
         } else if entry.file_type().is_file() {
@@ -514,7 +540,7 @@ pub fn build_source_dist(
             continue;
         };
 
-        add_source_dist_entry(&mut tar, entry, &top_level, &source_dist_path, &relative)?;
+        add_source_dist_entry(&mut tar, &entry, &top_level, &source_dist_path, &relative)?;
     }
 
     tar.finish()
@@ -526,7 +552,7 @@ pub fn build_source_dist(
 /// Add a file or a directory to a source distribution.
 fn add_source_dist_entry(
     tar: &mut Builder<GzEncoder<File>>,
-    entry: DirEntry,
+    entry: &DirEntry,
     top_level: &str,
     source_dist_path: &Path,
     relative: &Path,

crates/uv-build-backend/src/tests.rs

@@ -46,7 +46,14 @@ fn test_record() {
 fn test_determinism() {
     let temp1 = TempDir::new().unwrap();
     let uv_backend = Path::new("../../scripts/packages/uv_backend");
-    build_wheel(uv_backend, temp1.path(), None, "1.0.0+test").unwrap();
+    build_wheel(
+        uv_backend,
+        temp1.path(),
+        None,
+        WheelSettings::default(),
+        "1.0.0+test",
+    )
+    .unwrap();
 
     // Touch the file to check that we don't serialize the last modified date.
     fs_err::write(
@@ -56,7 +63,14 @@ fn test_determinism() {
     .unwrap();
 
     let temp2 = TempDir::new().unwrap();
-    build_wheel(uv_backend, temp2.path(), None, "1.0.0+test").unwrap();
+    build_wheel(
+        uv_backend,
+        temp2.path(),
+        None,
+        WheelSettings::default(),
+        "1.0.0+test",
+    )
+    .unwrap();
 
     let wheel_filename = "uv_backend-0.1.0-py3-none-any.whl";
     assert_eq!(

crates/uv/src/commands/build_backend.rs

@@ -4,7 +4,7 @@ use crate::commands::ExitStatus;
 use anyhow::Result;
 use std::env;
 use std::path::Path;
-use uv_build_backend::SourceDistSettings;
+use uv_build_backend::{SourceDistSettings, WheelSettings};
 
 pub(crate) fn build_sdist(sdist_directory: &Path) -> Result<ExitStatus> {
     let filename = uv_build_backend::build_source_dist(
@@ -24,6 +24,7 @@ pub(crate) fn build_wheel(
         &env::current_dir()?,
         wheel_directory,
         metadata_directory,
+        WheelSettings::default(),
         uv_version::version(),
     )?;
     println!("{filename}");