diff --git a/crates/uv-build-backend/src/lib.rs b/crates/uv-build-backend/src/lib.rs
index 4f038256d017..bd77661a22ad 100644
--- a/crates/uv-build-backend/src/lib.rs
+++ b/crates/uv-build-backend/src/lib.rs
@@ -8,6 +8,7 @@ pub use source_dist::{build_source_dist, list_source_dist};
pub use wheel::{build_editable, build_wheel, list_wheel, metadata};
use crate::metadata::ValidationError;
+use itertools::Itertools;
use std::fs::FileType;
use std::io;
use std::path::{Path, PathBuf};
@@ -15,7 +16,7 @@ use thiserror::Error;
use tracing::debug;
use uv_fs::Simplified;
use uv_globfilter::PortableGlobError;
-use uv_pypi_types::IdentifierParseError;
+use uv_pypi_types::{Identifier, IdentifierParseError};
#[derive(Debug, Error)]
pub enum Error {
@@ -54,8 +55,25 @@ pub enum Error {
Zip(#[from] zip::result::ZipError),
#[error("Failed to write RECORD file")]
Csv(#[from] csv::Error),
- #[error("Expected a Python module with an `__init__.py` at: `{}`", _0.user_display())]
+ #[error(
+ "Expected a Python module directory at: `{}`",
+ _0.user_display()
+ )]
MissingModule(PathBuf),
+ #[error(
+ "Expected an `__init__.py` at: `{}`",
+ _0.user_display()
+ )]
+ MissingInitPy(PathBuf),
+ #[error(
+ "Expected an `__init__.py` at `{}`, found multiple:\n* `{}`",
+ module_name,
+ paths.iter().map(Simplified::user_display).join("`\n* `")
+ )]
+ MultipleModules {
+ module_name: Identifier,
+ paths: Vec<PathBuf>,
+ },
#[error("Absolute module root is not allowed: `{}`", _0.display())]
AbsoluteModuleRoot(PathBuf),
#[error("Inconsistent metadata between prepare and build step: `{0}`")]
diff --git a/crates/uv-build-backend/src/wheel.rs b/crates/uv-build-backend/src/wheel.rs
index 08e7c434fea6..5a3f27765eaa 100644
--- a/crates/uv-build-backend/src/wheel.rs
+++ b/crates/uv-build-backend/src/wheel.rs
@@ -128,7 +128,7 @@ fn write_wheel(
if settings.module_root.is_absolute() {
return Err(Error::AbsoluteModuleRoot(settings.module_root.clone()));
}
- let strip_root = source_tree.join(settings.module_root);
+ let src_root = source_tree.join(settings.module_root);
let module_name = if let Some(module_name) = settings.module_name {
module_name
@@ -139,10 +139,8 @@ fn write_wheel(
};
debug!("Module name: `{:?}`", module_name);
- let module_root = strip_root.join(module_name.as_ref());
- if !module_root.join("__init__.py").is_file() {
- return Err(Error::MissingModule(module_root));
- }
+ let module_root = find_module_root(&src_root, module_name)?;
+
let mut files_visited = 0;
for entry in WalkDir::new(module_root)
.into_iter()
@@ -169,7 +167,7 @@ fn write_wheel(
.expect("walkdir starts with root");
let wheel_path = entry
.path()
- .strip_prefix(&strip_root)
+ .strip_prefix(&src_root)
.expect("walkdir starts with root");
if exclude_matcher.is_match(match_path) {
trace!("Excluding from module: `{}`", match_path.user_display());
@@ -243,6 +241,46 @@ fn write_wheel(
Ok(())
}
+/// Match the module name to its module directory with potentially different casing.
+///
+/// For example, a package may have the dist-info-normalized package name `pil_util`, but the
+/// importable module is named `PIL_util`.
+///
+/// We get the module either as dist-info-normalized package name, or explicitly from the user.
+/// For dist-info-normalizing a package name, the rules are lowercasing, replacing `.` with `_` and
+/// replace `-` with `_`. Since `.` and `-` are not allowed in module names, we can check whether a
+/// directory name matches our expected module name by lowercasing it.
+fn find_module_root(src_root: &Path, module_name: Identifier) -> Result<PathBuf, Error> {
+ let normalized = module_name.to_string();
+ let modules = fs_err::read_dir(src_root)?
+ .filter_ok(|entry| {
+ entry
+ .file_name()
+ .to_str()
+ .is_some_and(|file_name| file_name.to_lowercase() == normalized)
+ })
+ .map_ok(|entry| entry.path())
+ .collect::<Result<Vec<_>, _>>()?;
+ match modules.as_slice() {
+ [] => {
+ // Show the normalized path in the error message, as representative example.
+ Err(Error::MissingModule(src_root.join(module_name.as_ref())))
+ }
+ [module_root] => {
+ if module_root.join("__init__.py").is_file() {
+ Ok(module_root.clone())
+ } else {
+ Err(Error::MissingInitPy(module_root.join("__init__.py")))
+ }
+ }
+ multiple => {
+ let mut paths = multiple.to_vec();
+ paths.sort();
+ Err(Error::MultipleModules { module_name, paths })
+ }
+ }
+}
+
/// Build a wheel from the source tree and place it in the output directory.
pub fn build_editable(
source_tree: &Path,
@@ -292,10 +330,9 @@ pub fn build_editable(
};
debug!("Module name: `{:?}`", module_name);
- let module_root = src_root.join(module_name.as_ref());
- if !module_root.join("__init__.py").is_file() {
- return Err(Error::MissingModule(module_root));
- }
+ // Check that a module root exists in the directory we're linking from the `.pth` file
+ find_module_root(&src_root, module_name)?;
+
wheel_writer.write_bytes(
&format!("{}.pth", pyproject_toml.name().as_dist_info_name()),
src_root.as_os_str().as_encoded_bytes(),
diff --git a/crates/uv/tests/it/build_backend.rs b/crates/uv/tests/it/build_backend.rs
index d5e455c3e4c2..2d5556bfbad4 100644
--- a/crates/uv/tests/it/build_backend.rs
+++ b/crates/uv/tests/it/build_backend.rs
@@ -431,3 +431,119 @@ fn rename_module_editable_build() -> Result<()> {
Ok(())
}
+
+/// Check that the build succeeds even if the module name mismatches by case.
+#[test]
+fn build_module_name_normalization() -> Result<()> {
+ let context = TestContext::new("3.12");
+
+ let wheel_dir = context.temp_dir.path().join("dist");
+ fs_err::create_dir(&wheel_dir)?;
+
+ context
+ .temp_dir
+ .child("pyproject.toml")
+ .write_str(indoc! {r#"
+ [project]
+ name = "django-plugin"
+ version = "1.0.0"
+
+ [build-system]
+ requires = ["uv_build>=0.5,<0.7"]
+ build-backend = "uv_build"
+ "#})?;
+ fs_err::create_dir_all(context.temp_dir.join("src"))?;
+
+ // Error case 1: No matching module.
+ uv_snapshot!(context
+ .build_backend()
+ .arg("build-wheel")
+ .arg(&wheel_dir), @r###"
+ success: false
+ exit_code: 2
+ ----- stdout -----
+
+ ----- stderr -----
+ error: Expected a Python module directory at: `src/django_plugin`
+ "###);
+
+ fs_err::create_dir_all(context.temp_dir.join("src/Django_plugin"))?;
+ // Error case 2: A matching module, but no `__init__.py`.
+ uv_snapshot!(context
+ .build_backend()
+ .arg("build-wheel")
+ .arg(&wheel_dir), @r###"
+ success: false
+ exit_code: 2
+ ----- stdout -----
+
+ ----- stderr -----
+ error: Expected an `__init__.py` at: `src/Django_plugin/__init__.py`
+ "###);
+
+ // Use `Django_plugin` instead of `django_plugin`
+ context
+ .temp_dir
+ .child("src/Django_plugin/__init__.py")
+ .write_str(r#"print("Hi from bar")"#)?;
+
+ uv_snapshot!(context
+ .build_backend()
+ .arg("build-wheel")
+ .arg(&wheel_dir), @r"
+ success: true
+ exit_code: 0
+ ----- stdout -----
+ django_plugin-1.0.0-py3-none-any.whl
+
+ ----- stderr -----
+ ");
+
+ context
+ .pip_install()
+ .arg("--no-index")
+ .arg("--find-links")
+ .arg(&wheel_dir)
+ .arg("django-plugin")
+ .assert()
+ .success();
+
+ uv_snapshot!(Command::new(context.interpreter())
+ .arg("-c")
+ .arg("import Django_plugin")
+ // Python on windows
+ .env(EnvVars::PYTHONUTF8, "1"), @r"
+ success: true
+ exit_code: 0
+ ----- stdout -----
+ Hi from bar
+
+ ----- stderr -----
+ ");
+
+ // Error case 3: Multiple modules a matching name.
+ // Requires a case-sensitive filesystem.
+ #[cfg(target_os = "linux")]
+ {
+ context
+ .temp_dir
+ .child("src/django_plugin/__init__.py")
+ .write_str(r#"print("Hi from bar")"#)?;
+
+ uv_snapshot!(context
+ .build_backend()
+ .arg("build-wheel")
+ .arg(&wheel_dir), @r"
+ success: false
+ exit_code: 2
+ ----- stdout -----
+
+ ----- stderr -----
+ error: Expected a single Python module for `django_plugin` with an `__init__.py`, found multiple:
+ * `src/Django_plugin`
+ * `src/django_plugin`
+ ");
+ }
+
+ Ok(())
+}