Avoid prepare_metadata_for_build_wheel calls for Hatch packages with dynamic dependencies (#2645)

## Summary

Hatch allows for highly dynamic customization of metadata via hooks. In
such cases, Hatch
can't upload the PEP 517 contract, in that the metadata Hatch would
return by
`prepare_metadata_for_build_wheel` isn't guaranteed to match that of the
built wheel.

Hatch disables `prepare_metadata_for_build_wheel` entirely for pip.
We'll instead disable
it on our end when metadata is defined as "dynamic" in the
pyproject.toml, which should
allow us to leverage the hook in _most_ cases while still avoiding
incorrect metadata for
the remaining cases.

Closes: https://github.com/astral-sh/uv/issues/2130.

crates/uv-build/src/lib.rs

@@ -213,6 +213,9 @@ pub struct Project {
     pub version: Option<Version>,
     /// The Python version requirements of the project
     pub requires_python: Option<VersionSpecifiers>,
+    /// Specifies which fields listed by PEP 621 were intentionally unspecified so another tool
+    /// can/will provide such metadata dynamically.
+    pub dynamic: Option<Vec<String>>,
 }
 
 /// The `[build-system]` section of a pyproject.toml as specified in PEP 517.
@@ -347,6 +350,8 @@ pub struct SourceBuild {
     config_settings: ConfigSettings,
     /// If performing a PEP 517 build, the backend to use.
     pep517_backend: Option<Pep517Backend>,
+    /// The PEP 621 project metadata, if any.
+    project: Option<Project>,
     /// The virtual environment in which to build the source distribution.
     venv: PythonEnvironment,
     /// Populated if `prepare_metadata_for_build_wheel` was called.
@@ -399,8 +404,9 @@ impl SourceBuild {
         let default_backend: Pep517Backend = DEFAULT_BACKEND.clone();
 
         // Check if we have a PEP 517 build backend.
-        let pep517_backend = Self::get_pep517_backend(setup_py, &source_tree, &default_backend)
-            .map_err(|err| *err)?;
+        let (pep517_backend, project) =
+            Self::extract_pep517_backend(&source_tree, setup_py, &default_backend)
+                .map_err(|err| *err)?;
 
         // Create a virtual environment, or install into the shared environment if requested.
         let venv = match build_isolation {
@@ -487,6 +493,7 @@ impl SourceBuild {
             temp_dir,
             source_tree,
             pep517_backend,
+            project,
             venv,
             build_kind,
             config_settings,
@@ -542,17 +549,18 @@ impl SourceBuild {
         })
     }
 
-    fn get_pep517_backend(
-        setup_py: SetupPyStrategy,
+    /// Extract the PEP 517 backend from the `pyproject.toml` or `setup.py` file.
+    fn extract_pep517_backend(
         source_tree: &Path,
+        setup_py: SetupPyStrategy,
         default_backend: &Pep517Backend,
-    ) -> Result<Option<Pep517Backend>, Box<Error>> {
+    ) -> Result<(Option<Pep517Backend>, Option<Project>), Box<Error>> {
         match fs::read_to_string(source_tree.join("pyproject.toml")) {
             Ok(toml) => {
                 let pyproject_toml: PyProjectToml =
                     toml::from_str(&toml).map_err(Error::InvalidPyprojectToml)?;
-                if let Some(build_system) = pyproject_toml.build_system {
-                    Ok(Some(Pep517Backend {
+                let backend = if let Some(build_system) = pyproject_toml.build_system {
+                    Pep517Backend {
                         // If `build-backend` is missing, inject the legacy setuptools backend, but
                         // retain the `requires`, to match `pip` and `build`. Note that while PEP 517
                         // says that in this case we "should revert to the legacy behaviour of running
@@ -565,12 +573,13 @@ impl SourceBuild {
                             .unwrap_or_else(|| "setuptools.build_meta:__legacy__".to_string()),
                         backend_path: build_system.backend_path,
                         requirements: build_system.requires,
-                    }))
+                    }
                 } else {
                     // If a `pyproject.toml` is present, but `[build-system]` is missing, proceed with
                     // a PEP 517 build using the default backend, to match `pip` and `build`.
-                    Ok(Some(default_backend.clone()))
-                }
+                    default_backend.clone()
+                };
+                Ok((Some(backend), pyproject_toml.project))
             }
             Err(err) if err.kind() == io::ErrorKind::NotFound => {
                 // We require either a `pyproject.toml` or a `setup.py` file at the top level.
@@ -587,8 +596,8 @@ impl SourceBuild {
                 // 517 builds the default in the future.
                 // See: https://github.com/pypa/pip/issues/9175.
                 match setup_py {
-                    SetupPyStrategy::Pep517 => Ok(Some(default_backend.clone())),
-                    SetupPyStrategy::Setuptools => Ok(None),
+                    SetupPyStrategy::Pep517 => Ok((Some(default_backend.clone()), None)),
+                    SetupPyStrategy::Setuptools => Ok((None, None)),
                 }
             }
             Err(err) => Err(Box::new(err.into())),
@@ -607,6 +616,36 @@ impl SourceBuild {
             return Ok(Some(metadata_dir.clone()));
         }
 
+        // Hatch allows for highly dynamic customization of metadata via hooks. In such cases, Hatch
+        // can't uphold the PEP 517 contract, in that the metadata Hatch would return by
+        // `prepare_metadata_for_build_wheel` isn't guaranteed to match that of the built wheel.
+        //
+        // Hatch disables `prepare_metadata_for_build_wheel` entirely for pip. We'll instead disable
+        // it on our end when metadata is defined as "dynamic" in the pyproject.toml, which should
+        // allow us to leverage the hook in _most_ cases while still avoiding incorrect metadata for
+        // the remaining cases.
+        //
+        // This heuristic will have false positives (i.e., there will be some Hatch projects for
+        // which we could have safely called `prepare_metadata_for_build_wheel`, despite having
+        // dynamic metadata). However, false positives are preferable to false negatives, since
+        // this is just an optimization.
+        //
+        // See: https://github.com/astral-sh/uv/issues/2130
+        if pep517_backend.backend == "hatchling.build" {
+            if self
+                .project
+                .as_ref()
+                .and_then(|project| project.dynamic.as_ref())
+                .is_some_and(|dynamic| {
+                    dynamic
+                        .iter()
+                        .any(|field| field == "dependencies" || field == "optional-dependencies")
+                })
+            {
+                return Ok(None);
+            }
+        }
+
         let metadata_directory = self.temp_dir.path().join("metadata_directory");
         fs::create_dir(&metadata_directory)?;
 

crates/uv/tests/pip_compile.rs

@@ -6148,3 +6148,39 @@ fn unnamed_https_requirement() -> Result<()> {
 
     Ok(())
 }
+
+/// Detect the package name from metadata sources from local directories.
+#[test]
+fn dynamic_dependencies() -> Result<()> {
+    let context = TestContext::new("3.12");
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("hatchling-dynamic @ ../../scripts/packages/hatchling_dynamic")?;
+
+    let filter_path = regex::escape(&requirements_in.user_display().to_string());
+    let filters: Vec<_> = [(filter_path.as_str(), "requirements.in")]
+        .into_iter()
+        .chain(INSTA_FILTERS.to_vec())
+        .collect();
+
+    uv_snapshot!(filters, context.compile()
+        .arg(requirements_in.path())
+        .current_dir(current_dir()?), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z requirements.in
+    anyio==4.3.0
+        # via hatchling-dynamic
+    hatchling-dynamic @ ../../scripts/packages/hatchling_dynamic
+    idna==3.6
+        # via anyio
+    sniffio==1.3.1
+        # via anyio
+
+    ----- stderr -----
+    Resolved 4 packages in [TIME]
+    "###);
+
+    Ok(())
+}

scripts/packages/hatchling_dynamic/hatch_build.py

@@ -0,0 +1,6 @@
+from hatchling.builders.hooks.plugin.interface import BuildHookInterface
+
+
+class LiteraryBuildHook(BuildHookInterface):
+    def initialize(self, version, build_data):
+        build_data["dependencies"].append("anyio")

scripts/packages/hatchling_dynamic/pyproject.toml

@@ -0,0 +1,10 @@
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[project]
+name = "hatchling-dynamic"
+version = "1.0.0"
+dynamic = ["dependencies"]
+
+[tool.hatch.build.targets.wheel.hooks.custom]