Remove `--legacy-setup-py` command-line argument (#4255)

This is a fallback mode that we supported when we decided to use PEP 517 builds by default. I can't find a single reference to it on GitHub or in our issue tracker, so I want to drop support for it as part of v0.3.0.
2024-08-19 16:57:59 -04:00 · 2024-08-19 16:57:59 -04:00 · 732d2fb0fb
parent 47fb902104
commit 732d2fb0fb
23 changed files with 53 additions and 368 deletions
--- a/crates/bench/benches/uv.rs
+++ b/crates/bench/benches/uv.rs
@ -91,7 +91,7 @@ mod resolver {
    use uv_cache::Cache;
    use uv_client::RegistryClient;
    use uv_configuration::{
-        BuildOptions, Concurrency, ConfigSettings, IndexStrategy, SetupPyStrategy, SourceStrategy,
+        BuildOptions, Concurrency, ConfigSettings, IndexStrategy, SourceStrategy,
    };
    use uv_dispatch::BuildDispatch;
    use uv_distribution::DistributionDatabase;
@ -179,7 +179,6 @@ mod resolver {
            &git,
            &in_flight,
            IndexStrategy::default(),
-            SetupPyStrategy::default(),
            &config_settings,
            build_isolation,
            LinkMode::default(),
--- a/crates/uv-build/src/lib.rs
+++ b/crates/uv-build/src/lib.rs
@ -28,7 +28,7 @@ use distribution_types::Resolution;
 use pep440_rs::Version;
 use pep508_rs::PackageName;
 use pypi_types::{Requirement, VerbatimParsedUrl};
-use uv_configuration::{BuildKind, ConfigSettings, SetupPyStrategy};
+use uv_configuration::{BuildKind, ConfigSettings};
 use uv_fs::{rename_with_retry, PythonExt, Simplified};
 use uv_python::{Interpreter, PythonEnvironment};
 use uv_types::{BuildContext, BuildIsolation, SourceBuildTrait};
@ -75,14 +75,6 @@ static DEFAULT_BACKEND: LazyLock<Pep517Backend> = LazyLock::new(|| Pep517Backend
    )],
 });

-/// The requirements for `--legacy-setup-py` builds.
-static SETUP_PY_REQUIREMENTS: LazyLock<[Requirement; 2]> = LazyLock::new(|| {
-    [
-        Requirement::from(pep508_rs::Requirement::from_str("setuptools >= 40.8.0").unwrap()),
-        Requirement::from(pep508_rs::Requirement::from_str("wheel").unwrap()),
-    ]
-});
-
 #[derive(Error, Debug)]
 pub enum Error {
    #[error(transparent)]
@ -359,8 +351,6 @@ impl Pep517Backend {
 pub struct SourceBuildContext {
    /// An in-memory resolution of the default backend's requirements for PEP 517 builds.
    default_resolution: Rc<Mutex<Option<Resolution>>>,
-    /// An in-memory resolution of the build requirements for `--legacy-setup-py` builds.
-    setup_py_resolution: Rc<Mutex<Option<Resolution>>>,
 }

 /// Holds the state through a series of PEP 517 frontend to backend calls or a single setup.py
@ -373,7 +363,7 @@ pub struct SourceBuild {
    source_tree: PathBuf,
    config_settings: ConfigSettings,
    /// If performing a PEP 517 build, the backend to use.
-    pep517_backend: Option<Pep517Backend>,
+    pep517_backend: Pep517Backend,
    /// The PEP 621 project metadata, if any.
    project: Option<Project>,
    /// The virtual environment in which to build the source distribution.
@ -412,7 +402,6 @@ impl SourceBuild {
        build_context: &impl BuildContext,
        source_build_context: SourceBuildContext,
        version_id: String,
-        setup_py: SetupPyStrategy,
        config_settings: ConfigSettings,
        build_isolation: BuildIsolation<'_>,
        build_kind: BuildKind,
@ -431,8 +420,7 @@ impl SourceBuild {

        // Check if we have a PEP 517 build backend.
        let (pep517_backend, project) =
-            Self::extract_pep517_backend(&source_tree, setup_py, &default_backend)
-                .map_err(|err| *err)?;
+            Self::extract_pep517_backend(&source_tree, &default_backend).map_err(|err| *err)?;

        let package_name = project.clone().map(|p| p.name);

@ -457,7 +445,7 @@ impl SourceBuild {
                build_context,
                source_build_context,
                &default_backend,
-                pep517_backend.as_ref(),
+                &pep517_backend,
            )
            .await?;

@ -503,22 +491,20 @@ impl SourceBuild {
        // environment is already setup.
        let runner = PythonRunner::new(concurrent_builds);
        if build_isolation.is_isolated(package_name.as_ref()) {
-            if let Some(pep517_backend) = &pep517_backend {
-                create_pep517_build_environment(
-                    &runner,
-                    &source_tree,
-                    &venv,
-                    pep517_backend,
-                    build_context,
-                    &version_id,
-                    build_kind,
-                    &config_settings,
-                    &environment_variables,
-                    &modified_path,
-                    &temp_dir,
-                )
-                .await?;
-            }
+            create_pep517_build_environment(
+                &runner,
+                &source_tree,
+                &venv,
+                &pep517_backend,
+                build_context,
+                &version_id,
+                build_kind,
+                &config_settings,
+                &environment_variables,
+                &modified_path,
+                &temp_dir,
+            )
+            .await?;
        }

        Ok(Self {
@ -541,9 +527,9 @@ impl SourceBuild {
        build_context: &impl BuildContext,
        source_build_context: SourceBuildContext,
        default_backend: &Pep517Backend,
-        pep517_backend: Option<&Pep517Backend>,
+        pep517_backend: &Pep517Backend,
    ) -> Result<Resolution, Error> {
-        Ok(if let Some(pep517_backend) = pep517_backend {
+        Ok(
            if pep517_backend.requirements == default_backend.requirements {
                let mut resolution = source_build_context.default_resolution.lock().await;
                if let Some(resolved_requirements) = &*resolution {
@ -565,29 +551,15 @@ impl SourceBuild {
                    .map_err(|err| {
                        Error::RequirementsInstall("build-system.requires (resolve)", err)
                    })?
-            }
-        } else {
-            // Install default requirements for `setup.py`-based builds.
-            let mut resolution = source_build_context.setup_py_resolution.lock().await;
-            if let Some(resolved_requirements) = &*resolution {
-                resolved_requirements.clone()
-            } else {
-                let resolved_requirements = build_context
-                    .resolve(&*SETUP_PY_REQUIREMENTS)
-                    .await
-                    .map_err(|err| Error::RequirementsInstall("setup.py build (resolve)", err))?;
-                *resolution = Some(resolved_requirements.clone());
-                resolved_requirements
-            }
-        })
+            },
+        )
    }

    /// 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>, Option<Project>), Box<Error>> {
+    ) -> Result<(Pep517Backend, Option<Project>), Box<Error>> {
        match fs::read_to_string(source_tree.join("pyproject.toml")) {
            Ok(toml) => {
                let pyproject_toml: PyProjectToml =
@ -616,7 +588,7 @@ impl SourceBuild {
                    // a PEP 517 build using the default backend, to match `pip` and `build`.
                    default_backend.clone()
                };
-                Ok((Some(backend), pyproject_toml.project))
+                Ok((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.
@ -629,13 +601,9 @@ impl SourceBuild {

                // If no `pyproject.toml` is present, by default, proceed with a PEP 517 build using
                // the default backend, to match `build`. `pip` uses `setup.py` directly in this
-                // case (which we allow via `SetupPyStrategy::Setuptools`), but plans to make PEP
-                // 517 builds the default in the future.
+                // case,  but plans to make PEP 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()), None)),
-                    SetupPyStrategy::Setuptools => Ok((None, None)),
-                }
+                Ok((default_backend.clone(), None))
            }
            Err(err) => Err(Box::new(err.into())),
        }
@ -644,10 +612,6 @@ impl SourceBuild {
    /// Try calling `prepare_metadata_for_build_wheel` to get the metadata without executing the
    /// actual build.
    pub async fn get_metadata_without_build(&mut self) -> Result<Option<PathBuf>, Error> {
-        let Some(pep517_backend) = &self.pep517_backend else {
-            return Ok(None);
-        };
-
        // We've already called this method; return the existing result.
        if let Some(metadata_dir) = &self.metadata_directory {
            return Ok(Some(metadata_dir.clone()));
@ -668,7 +632,7 @@ impl SourceBuild {
        // this is just an optimization.
        //
        // See: https://github.com/astral-sh/uv/issues/2130
-        if pep517_backend.backend == "hatchling.build" {
+        if self.pep517_backend.backend == "hatchling.build" {
            if self
                .project
                .as_ref()
@ -694,7 +658,7 @@ impl SourceBuild {

        debug!(
            "Calling `{}.prepare_metadata_for_build_{}()`",
-            pep517_backend.backend, self.build_kind,
+            self.pep517_backend.backend, self.build_kind,
        );
        let script = formatdoc! {
            r#"
@ -710,7 +674,7 @@ impl SourceBuild {
            with open("{}", "w") as fp:
                fp.write(dirname or "")
            "#,
-            pep517_backend.backend_import(),
+            self.pep517_backend.backend_import(),
            self.build_kind,
            escape_path_for_python(&metadata_directory),
            self.config_settings.escape_for_python(),
@ -760,55 +724,16 @@ impl SourceBuild {
        // The build scripts run with the extracted root as cwd, so they need the absolute path.
        let wheel_dir = fs::canonicalize(wheel_dir)?;

-        if let Some(pep517_backend) = &self.pep517_backend {
-            // Prevent clashes from two uv processes building wheels in parallel.
-            let tmp_dir = tempdir_in(&wheel_dir)?;
-            let filename = self.pep517_build(tmp_dir.path(), pep517_backend).await?;
+        // Prevent clashes from two uv processes building wheels in parallel.
+        let tmp_dir = tempdir_in(&wheel_dir)?;
+        let filename = self
+            .pep517_build(tmp_dir.path(), &self.pep517_backend)
+            .await?;

-            let from = tmp_dir.path().join(&filename);
-            let to = wheel_dir.join(&filename);
-            rename_with_retry(from, to).await?;
-            Ok(filename)
-        } else {
-            if self.build_kind != BuildKind::Wheel {
-                return Err(Error::EditableSetupPy);
-            }
-            // We checked earlier that setup.py exists.
-            let span = info_span!(
-                "run_python_script",
-                script="setup.py bdist_wheel",
-                python_version = %self.venv.interpreter().python_version()
-            );
-            let output = self
-                .runner
-                .run_setup_py(&self.venv, "bdist_wheel", &self.source_tree)
-                .instrument(span)
-                .await?;
-            if !output.status.success() {
-                return Err(Error::from_command_output(
-                    "Failed building wheel through setup.py".to_string(),
-                    &output,
-                    &self.version_id,
-                ));
-            }
-            let dist = fs::read_dir(self.source_tree.join("dist"))?;
-            let dist_dir = dist.collect::<io::Result<Vec<fs_err::DirEntry>>>()?;
-            let [dist_wheel] = dist_dir.as_slice() else {
-                return Err(Error::from_command_output(
-                    format!(
-                        "Expected exactly wheel in `dist/` after invoking setup.py, found {dist_dir:?}"
-                    ),
-                    &output,
-                    &self.version_id)
-                );
-            };
-
-            let from = dist_wheel.path();
-            let to = wheel_dir.join(dist_wheel.file_name());
-            fs_err::copy(from, to)?;
-
-            Ok(dist_wheel.file_name().to_string_lossy().to_string())
-        }
+        let from = tmp_dir.path().join(&filename);
+        let to = wheel_dir.join(&filename);
+        rename_with_retry(from, to).await?;
+        Ok(filename)
    }

    async fn pep517_build(
@ -1072,28 +997,6 @@ impl PythonRunner {
            .await
            .map_err(|err| Error::CommandFailed(venv.python_executable().to_path_buf(), err))
    }
-
-    /// Spawn a process that runs a `setup.py` script.
-    ///
-    /// If the concurrency limit has been reached this method will wait until a pending
-    /// script completes before spawning this one.
-    ///
-    /// Note: It is the caller's responsibility to create an informative span.
-    async fn run_setup_py(
-        &self,
-        venv: &PythonEnvironment,
-        script: &str,
-        source_tree: &Path,
-    ) -> Result<Output, Error> {
-        let _permit = self.control.acquire().await.unwrap();
-
-        Command::new(venv.python_executable())
-            .args(["setup.py", script])
-            .current_dir(source_tree.simplified())
-            .output()
-            .await
-            .map_err(|err| Error::CommandFailed(venv.python_executable().to_path_buf(), err))
-    }
 }

 #[cfg(test)]
--- a/crates/uv-cli/src/lib.rs
+++ b/crates/uv-cli/src/lib.rs
@ -869,14 +869,6 @@ pub struct PipCompileArgs {
    #[arg(long, overrides_with("generate_hashes"), hide = true)]
    pub no_generate_hashes: bool,

-    /// Use legacy `setuptools` behavior when building source distributions without a
-    /// `pyproject.toml`.
-    #[arg(long, overrides_with("no_legacy_setup_py"))]
-    pub legacy_setup_py: bool,
-
-    #[arg(long, overrides_with("legacy_setup_py"), hide = true)]
-    pub no_legacy_setup_py: bool,
-
    /// Don't build source distributions.
    ///
    /// When enabled, resolving will not run arbitrary Python code. The cached wheels of
@ -1159,14 +1151,6 @@ pub struct PipSyncArgs {
    #[arg(long, conflicts_with = "target")]
    pub prefix: Option<PathBuf>,

-    /// Use legacy `setuptools` behavior when building source distributions without a
-    /// `pyproject.toml`.
-    #[arg(long, overrides_with("no_legacy_setup_py"))]
-    pub legacy_setup_py: bool,
-
-    #[arg(long, overrides_with("legacy_setup_py"), hide = true)]
-    pub no_legacy_setup_py: bool,
-
    /// Don't build source distributions.
    ///
    /// When enabled, resolving will not run arbitrary Python code. The cached wheels of
@ -1449,14 +1433,6 @@ pub struct PipInstallArgs {
    #[arg(long, conflicts_with = "target")]
    pub prefix: Option<PathBuf>,

-    /// Use legacy `setuptools` behavior when building source distributions without a
-    /// `pyproject.toml`.
-    #[arg(long, overrides_with("no_legacy_setup_py"))]
-    pub legacy_setup_py: bool,
-
-    #[arg(long, overrides_with("legacy_setup_py"), hide = true)]
-    pub no_legacy_setup_py: bool,
-
    /// Don't build source distributions.
    ///
    /// When enabled, resolving will not run arbitrary Python code. The cached wheels of
--- a/crates/uv-configuration/src/build_options.rs
+++ b/crates/uv-configuration/src/build_options.rs
@ -4,16 +4,6 @@ use pep508_rs::PackageName;

 use crate::{PackageNameSpecifier, PackageNameSpecifiers};

-/// The strategy to use when building source distributions that lack a `pyproject.toml`.
-#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
-pub enum SetupPyStrategy {
-    /// Perform a PEP 517 build.
-    #[default]
-    Pep517,
-    /// Perform a build by invoking `setuptools` directly.
-    Setuptools,
-}
-
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 pub enum BuildKind {
    /// A regular PEP 517 wheel build
--- a/crates/uv-dev/src/build.rs
+++ b/crates/uv-dev/src/build.rs
@ -11,8 +11,7 @@ use uv_build::{SourceBuild, SourceBuildContext};
 use uv_cache::{Cache, CacheArgs};
 use uv_client::RegistryClientBuilder;
 use uv_configuration::{
-    BuildKind, BuildOptions, Concurrency, ConfigSettings, IndexStrategy, SetupPyStrategy,
-    SourceStrategy,
+    BuildKind, BuildOptions, Concurrency, ConfigSettings, IndexStrategy, SourceStrategy,
 };
 use uv_dispatch::BuildDispatch;
 use uv_git::GitResolver;
@ -67,7 +66,6 @@ pub(crate) async fn build(args: BuildArgs) -> Result<PathBuf> {
    let index = InMemoryIndex::default();
    let index_urls = IndexLocations::default();
    let index_strategy = IndexStrategy::default();
-    let setup_py = SetupPyStrategy::default();
    let sources = SourceStrategy::default();
    let python = PythonEnvironment::find(
        &PythonRequest::default(),
@ -88,7 +86,6 @@ pub(crate) async fn build(args: BuildArgs) -> Result<PathBuf> {
        &git,
        &in_flight,
        index_strategy,
-        setup_py,
        &config_settings,
        BuildIsolation::Isolated,
        install_wheel_rs::linker::LinkMode::default(),
@ -105,7 +102,6 @@ pub(crate) async fn build(args: BuildArgs) -> Result<PathBuf> {
        &build_dispatch,
        SourceBuildContext::default(),
        args.sdist.display().to_string(),
-        setup_py,
        config_settings.clone(),
        BuildIsolation::Isolated,
        build_kind,
--- a/crates/uv-dispatch/src/lib.rs
+++ b/crates/uv-dispatch/src/lib.rs
@ -18,8 +18,7 @@ use uv_cache::Cache;
 use uv_client::RegistryClient;
 use uv_configuration::Concurrency;
 use uv_configuration::{
-    BuildKind, BuildOptions, ConfigSettings, Constraints, IndexStrategy, Reinstall,
-    SetupPyStrategy, SourceStrategy,
+    BuildKind, BuildOptions, ConfigSettings, Constraints, IndexStrategy, Reinstall, SourceStrategy,
 };
 use uv_distribution::DistributionDatabase;
 use uv_git::GitResolver;
@ -44,7 +43,6 @@ pub struct BuildDispatch<'a> {
    index: &'a InMemoryIndex,
    git: &'a GitResolver,
    in_flight: &'a InFlight,
-    setup_py: SetupPyStrategy,
    build_isolation: BuildIsolation<'a>,
    link_mode: install_wheel_rs::linker::LinkMode,
    build_options: &'a BuildOptions,
@ -68,7 +66,6 @@ impl<'a> BuildDispatch<'a> {
        git: &'a GitResolver,
        in_flight: &'a InFlight,
        index_strategy: IndexStrategy,
-        setup_py: SetupPyStrategy,
        config_settings: &'a ConfigSettings,
        build_isolation: BuildIsolation<'a>,
        link_mode: install_wheel_rs::linker::LinkMode,
@ -88,7 +85,6 @@ impl<'a> BuildDispatch<'a> {
            git,
            in_flight,
            index_strategy,
-            setup_py,
            config_settings,
            build_isolation,
            link_mode,
@ -326,7 +322,6 @@ impl<'a> BuildContext for BuildDispatch<'a> {
            self,
            self.source_build_context.clone(),
            version_id.to_string(),
-            self.setup_py,
            self.config_settings.clone(),
            self.build_isolation,
            build_kind,
--- a/crates/uv-settings/src/settings.rs
+++ b/crates/uv-settings/src/settings.rs
@ -948,16 +948,6 @@ pub struct PipOptions {
        "#
    )]
    pub generate_hashes: Option<bool>,
-    /// Use legacy `setuptools` behavior when building source distributions without a
-    /// `pyproject.toml`.
-    #[option(
-        default = "false",
-        value_type = "bool",
-        example = r#"
-            legacy-setup-py = true
-        "#
-    )]
-    pub legacy_setup_py: Option<bool>,
    /// Settings to pass to the [PEP 517](https://peps.python.org/pep-0517/) build backend,
    /// specified as `KEY=VALUE` pairs.
    #[option(
--- a/crates/uv/src/commands/pip/compile.rs
+++ b/crates/uv/src/commands/pip/compile.rs
@ -16,7 +16,7 @@ use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
    BuildOptions, Concurrency, ConfigSettings, ExtrasSpecification, IndexStrategy, NoBinary,
-    NoBuild, Reinstall, SetupPyStrategy, SourceStrategy, Upgrade,
+    NoBuild, Reinstall, SourceStrategy, Upgrade,
 };
 use uv_configuration::{KeyringProviderType, TargetTriple};
 use uv_dispatch::BuildDispatch;
@ -73,7 +73,6 @@ pub(crate) async fn pip_compile(
    index_locations: IndexLocations,
    index_strategy: IndexStrategy,
    keyring_provider: KeyringProviderType,
-    setup_py: SetupPyStrategy,
    config_settings: ConfigSettings,
    connectivity: Connectivity,
    no_build_isolation: bool,
@ -322,7 +321,6 @@ pub(crate) async fn pip_compile(
        &git,
        &in_flight,
        index_strategy,
-        setup_py,
        &config_settings,
        build_isolation,
        link_mode,
--- a/crates/uv/src/commands/pip/install.rs
+++ b/crates/uv/src/commands/pip/install.rs
@ -14,7 +14,7 @@ use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
    BuildOptions, Concurrency, ConfigSettings, ExtrasSpecification, HashCheckingMode,
-    IndexStrategy, Reinstall, SetupPyStrategy, SourceStrategy, Upgrade,
+    IndexStrategy, Reinstall, SourceStrategy, Upgrade,
 };
 use uv_configuration::{KeyringProviderType, TargetTriple};
 use uv_dispatch::BuildDispatch;
@ -57,7 +57,6 @@ pub(crate) async fn pip_install(
    link_mode: LinkMode,
    compile: bool,
    hash_checking: Option<HashCheckingMode>,
-    setup_py: SetupPyStrategy,
    connectivity: Connectivity,
    config_settings: &ConfigSettings,
    no_build_isolation: bool,
@ -312,7 +311,6 @@ pub(crate) async fn pip_install(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_settings,
        build_isolation,
        link_mode,
--- a/crates/uv/src/commands/pip/sync.rs
+++ b/crates/uv/src/commands/pip/sync.rs
@ -13,7 +13,7 @@ use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
    BuildOptions, Concurrency, ConfigSettings, ExtrasSpecification, HashCheckingMode,
-    IndexStrategy, Reinstall, SetupPyStrategy, SourceStrategy, Upgrade,
+    IndexStrategy, Reinstall, SourceStrategy, Upgrade,
 };
 use uv_configuration::{KeyringProviderType, TargetTriple};
 use uv_dispatch::BuildDispatch;
@ -48,7 +48,6 @@ pub(crate) async fn pip_sync(
    index_locations: IndexLocations,
    index_strategy: IndexStrategy,
    keyring_provider: KeyringProviderType,
-    setup_py: SetupPyStrategy,
    allow_empty_requirements: bool,
    connectivity: Connectivity,
    config_settings: &ConfigSettings,
@ -258,7 +257,6 @@ pub(crate) async fn pip_sync(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_settings,
        build_isolation,
        link_mode,
--- a/crates/uv/src/commands/project/add.rs
+++ b/crates/uv/src/commands/project/add.rs
@ -11,7 +11,7 @@ use tracing::debug;
 use uv_auth::{store_credentials_from_url, Credentials};
 use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
-use uv_configuration::{Concurrency, ExtrasSpecification, SetupPyStrategy, SourceStrategy};
+use uv_configuration::{Concurrency, ExtrasSpecification, SourceStrategy};
 use uv_dispatch::BuildDispatch;
 use uv_distribution::DistributionDatabase;
 use uv_fs::{Simplified, CWD};
@ -234,7 +234,6 @@ pub(crate) async fn add(
    let python_version = None;
    let python_platform = None;
    let hasher = HashStrategy::default();
-    let setup_py = SetupPyStrategy::default();
    let build_isolation = BuildIsolation::default();

    // Determine the environment for the resolution.
@ -279,7 +278,6 @@ pub(crate) async fn add(
        &state.git,
        &state.in_flight,
        settings.index_strategy,
-        setup_py,
        &settings.config_setting,
        build_isolation,
        settings.link_mode,
--- a/crates/uv/src/commands/project/lock.rs
+++ b/crates/uv/src/commands/project/lock.rs
@ -14,7 +14,7 @@ use pypi_types::Requirement;
 use uv_auth::store_credentials_from_url;
 use uv_cache::Cache;
 use uv_client::{Connectivity, FlatIndexClient, RegistryClientBuilder};
-use uv_configuration::{Concurrency, ExtrasSpecification, Reinstall, SetupPyStrategy, Upgrade};
+use uv_configuration::{Concurrency, ExtrasSpecification, Reinstall, Upgrade};
 use uv_dispatch::BuildDispatch;
 use uv_distribution::DistributionDatabase;
 use uv_fs::CWD;
@ -383,7 +383,6 @@ async fn do_lock(
    // optional on the downstream APIs.
    let build_constraints = [];
    let extras = ExtrasSpecification::default();
-    let setup_py = SetupPyStrategy::default();

    // Resolve the flat indexes from `--find-links`.
    let flat_index = {
@ -404,7 +403,6 @@ async fn do_lock(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        link_mode,
--- a/crates/uv/src/commands/project/mod.rs
+++ b/crates/uv/src/commands/project/mod.rs
@ -11,7 +11,7 @@ use pypi_types::Requirement;
 use uv_auth::store_credentials_from_url;
 use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
-use uv_configuration::{Concurrency, ExtrasSpecification, Reinstall, SetupPyStrategy, Upgrade};
+use uv_configuration::{Concurrency, ExtrasSpecification, Reinstall, Upgrade};
 use uv_dispatch::BuildDispatch;
 use uv_distribution::DistributionDatabase;
 use uv_fs::Simplified;
@ -451,7 +451,6 @@ pub(crate) async fn resolve_names(
    // TODO(charlie): These are all default values. We should consider whether we want to make them
    // optional on the downstream APIs.
    let hasher = HashStrategy::default();
-    let setup_py = SetupPyStrategy::default();
    let flat_index = FlatIndex::default();
    let build_constraints = [];

@ -467,7 +466,6 @@ pub(crate) async fn resolve_names(
        &state.git,
        &state.in_flight,
        *index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        *link_mode,
@ -576,7 +574,6 @@ pub(crate) async fn resolve_environment<'a>(
    let extras = ExtrasSpecification::default();
    let hasher = HashStrategy::default();
    let preferences = Vec::default();
-    let setup_py = SetupPyStrategy::default();
    let build_constraints = [];

    // When resolving from an interpreter, we assume an empty environment, so reinstalls and
@ -603,7 +600,6 @@ pub(crate) async fn resolve_environment<'a>(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        link_mode,
@ -705,7 +701,6 @@ pub(crate) async fn sync_environment(
    let build_constraints = [];
    let dry_run = false;
    let hasher = HashStrategy::default();
-    let setup_py = SetupPyStrategy::default();

    // Resolve the flat indexes from `--find-links`.
    let flat_index = {
@ -726,7 +721,6 @@ pub(crate) async fn sync_environment(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        link_mode,
@ -899,7 +893,6 @@ pub(crate) async fn update_environment(
    let extras = ExtrasSpecification::default();
    let hasher = HashStrategy::default();
    let preferences = Vec::default();
-    let setup_py = SetupPyStrategy::default();

    // Resolve the flat indexes from `--find-links`.
    let flat_index = {
@ -920,7 +913,6 @@ pub(crate) async fn update_environment(
        &state.git,
        &state.in_flight,
        *index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        *link_mode,
--- a/crates/uv/src/commands/project/sync.rs
+++ b/crates/uv/src/commands/project/sync.rs
@ -4,7 +4,7 @@ use pep508_rs::MarkerTree;
 use uv_auth::store_credentials_from_url;
 use uv_cache::Cache;
 use uv_client::{Connectivity, FlatIndexClient, RegistryClientBuilder};
-use uv_configuration::{Concurrency, ExtrasSpecification, HashCheckingMode, SetupPyStrategy};
+use uv_configuration::{Concurrency, ExtrasSpecification, HashCheckingMode};
 use uv_dispatch::BuildDispatch;
 use uv_fs::CWD;
 use uv_installer::SitePackages;
@ -216,7 +216,6 @@ pub(super) async fn do_sync(
    // optional on the downstream APIs.
    let build_constraints = [];
    let dry_run = false;
-    let setup_py = SetupPyStrategy::default();

    // Extract the hashes from the lockfile.
    let hasher = HashStrategy::from_resolution(&resolution, HashCheckingMode::Verify)?;
@ -240,7 +239,6 @@ pub(super) async fn do_sync(
        &state.git,
        &state.in_flight,
        index_strategy,
-        setup_py,
        config_setting,
        build_isolation,
        link_mode,
--- a/crates/uv/src/commands/venv.rs
+++ b/crates/uv/src/commands/venv.rs
@ -17,7 +17,7 @@ use uv_cache::Cache;
 use uv_client::{BaseClientBuilder, Connectivity, FlatIndexClient, RegistryClientBuilder};
 use uv_configuration::{
    BuildOptions, Concurrency, ConfigSettings, IndexStrategy, KeyringProviderType, NoBinary,
-    NoBuild, SetupPyStrategy, SourceStrategy,
+    NoBuild, SourceStrategy,
 };
 use uv_dispatch::BuildDispatch;
 use uv_fs::{Simplified, CWD};
@ -274,7 +274,6 @@ async fn venv_impl(
        // For seed packages, assume a bunch of default settings are sufficient.
        let build_constraints = [];
        let config_settings = ConfigSettings::default();
-        let setup_py = SetupPyStrategy::default();
        let sources = SourceStrategy::Disabled;

        // Do not allow builds
@ -292,7 +291,6 @@ async fn venv_impl(
            &state.git,
            &state.in_flight,
            index_strategy,
-            setup_py,
            &config_settings,
            BuildIsolation::Isolated,
            link_mode,
--- a/crates/uv/src/lib.rs
+++ b/crates/uv/src/lib.rs
@ -306,7 +306,6 @@ async fn run(cli: Cli) -> Result<ExitStatus> {
                args.settings.index_locations,
                args.settings.index_strategy,
                args.settings.keyring_provider,
-                args.settings.setup_py,
                args.settings.config_setting,
                globals.connectivity,
                args.settings.no_build_isolation,
@ -373,7 +372,6 @@ async fn run(cli: Cli) -> Result<ExitStatus> {
                args.settings.index_locations,
                args.settings.index_strategy,
                args.settings.keyring_provider,
-                args.settings.setup_py,
                args.settings.allow_empty_requirements,
                globals.connectivity,
                &args.settings.config_setting,
@ -461,7 +459,6 @@ async fn run(cli: Cli) -> Result<ExitStatus> {
                args.settings.link_mode,
                args.settings.compile_bytecode,
                args.settings.hash_checking,
-                args.settings.setup_py,
                globals.connectivity,
                &args.settings.config_setting,
                args.settings.no_build_isolation,
--- a/crates/uv/src/settings.rs
+++ b/crates/uv/src/settings.rs
@ -23,8 +23,8 @@ use uv_cli::{
 use uv_client::Connectivity;
 use uv_configuration::{
    BuildOptions, Concurrency, ConfigSettings, ExtrasSpecification, HashCheckingMode,
-    IndexStrategy, KeyringProviderType, NoBinary, NoBuild, PreviewMode, Reinstall, SetupPyStrategy,
-    SourceStrategy, TargetTriple, Upgrade,
+    IndexStrategy, KeyringProviderType, NoBinary, NoBuild, PreviewMode, Reinstall, SourceStrategy,
+    TargetTriple, Upgrade,
 };
 use uv_normalize::PackageName;
 use uv_python::{Prefix, PythonDownloads, PythonPreference, PythonVersion, Target};
@ -937,8 +937,6 @@ impl PipCompileSettings {
            no_system,
            generate_hashes,
            no_generate_hashes,
-            legacy_setup_py,
-            no_legacy_setup_py,
            no_build,
            build,
            no_binary,
@ -1023,7 +1021,6 @@ impl PipCompileSettings {
                    no_header: flag(no_header, header),
                    custom_compile_command,
                    generate_hashes: flag(generate_hashes, no_generate_hashes),
-                    legacy_setup_py: flag(legacy_setup_py, no_legacy_setup_py),
                    python_version,
                    python_platform,
                    universal: flag(universal, no_universal),
@ -1076,8 +1073,6 @@ impl PipSyncSettings {
            prefix,
            allow_empty_requirements,
            no_allow_empty_requirements,
-            legacy_setup_py,
-            no_legacy_setup_py,
            no_build,
            build,
            no_binary,
@ -1118,7 +1113,6 @@ impl PipSyncSettings {
                        allow_empty_requirements,
                        no_allow_empty_requirements,
                    ),
-                    legacy_setup_py: flag(legacy_setup_py, no_legacy_setup_py),
                    python_version,
                    python_platform,
                    strict: flag(strict, no_strict),
@ -1175,8 +1169,6 @@ impl PipInstallSettings {
            no_break_system_packages,
            target,
            prefix,
-            legacy_setup_py,
-            no_legacy_setup_py,
            no_build,
            build,
            no_binary,
@ -1251,7 +1243,6 @@ impl PipInstallSettings {
                    extra,
                    all_extras: flag(all_extras, no_all_extras),
                    no_deps: flag(no_deps, deps),
-                    legacy_setup_py: flag(legacy_setup_py, no_legacy_setup_py),
                    python_version,
                    python_platform,
                    require_hashes: flag(require_hashes, no_require_hashes),
@ -1839,7 +1830,6 @@ pub(crate) struct PipSettings {
    pub(crate) no_header: bool,
    pub(crate) custom_compile_command: Option<String>,
    pub(crate) generate_hashes: bool,
-    pub(crate) setup_py: SetupPyStrategy,
    pub(crate) config_setting: ConfigSettings,
    pub(crate) python_version: Option<PythonVersion>,
    pub(crate) python_platform: Option<TargetTriple>,
@ -1898,7 +1888,6 @@ impl PipSettings {
            no_header,
            custom_compile_command,
            generate_hashes,
-            legacy_setup_py,
            config_settings,
            python_version,
            python_platform,
@ -2025,15 +2014,6 @@ impl PipSettings {
                .allow_empty_requirements
                .combine(allow_empty_requirements)
                .unwrap_or_default(),
-            setup_py: if args
-                .legacy_setup_py
-                .combine(legacy_setup_py)
-                .unwrap_or_default()
-            {
-                SetupPyStrategy::Setuptools
-            } else {
-                SetupPyStrategy::Pep517
-            },
            no_build_isolation: args
                .no_build_isolation
                .combine(no_build_isolation)
--- a/crates/uv/tests/pip_compile.rs
+++ b/crates/uv/tests/pip_compile.rs
@ -4119,7 +4119,7 @@ fn trailing_slash() -> Result<()> {
    Ok(())
 }

-/// Resolve a project without a `pyproject.toml`, using the PEP 517 build backend (default).
+/// Resolve a project without a `pyproject.toml`, using the PEP 517 build backend.
 #[test]
 fn compile_legacy_sdist_pep_517() -> Result<()> {
    let context = TestContext::new("3.12");
@ -4150,38 +4150,6 @@ fn compile_legacy_sdist_pep_517() -> Result<()> {
    Ok(())
 }

-/// Resolve a project without a `pyproject.toml`, using `setuptools` directly.
-#[test]
-fn compile_legacy_sdist_setuptools() -> Result<()> {
-    let context = TestContext::new("3.12");
-    let requirements_in = context.temp_dir.child("requirements.in");
-    requirements_in.write_str("flake8 @ https://files.pythonhosted.org/packages/66/53/3ad4a3b74d609b3b9008a10075c40e7c8909eae60af53623c3888f7a529a/flake8-6.0.0.tar.gz")?;
-
-    uv_snapshot!(context.filters(), context.pip_compile()
-            .arg("requirements.in")
-            .arg("--legacy-setup-py"), @r###"
-    success: true
-    exit_code: 0
-    ----- stdout -----
-    # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] requirements.in --legacy-setup-py
-    flake8 @ https://files.pythonhosted.org/packages/66/53/3ad4a3b74d609b3b9008a10075c40e7c8909eae60af53623c3888f7a529a/flake8-6.0.0.tar.gz
-        # via -r requirements.in
-    mccabe==0.7.0
-        # via flake8
-    pycodestyle==2.10.0
-        # via flake8
-    pyflakes==3.0.1
-        # via flake8
-
-    ----- stderr -----
-    Resolved 4 packages in [TIME]
-    "###
-    );
-
-    Ok(())
-}
-
 /// Include hashes from the registry in the generated output.
 #[test]
 fn generate_hashes_registry() -> Result<()> {
--- a/crates/uv/tests/pip_sync.rs
+++ b/crates/uv/tests/pip_sync.rs
@ -2610,7 +2610,7 @@ fn incompatible_wheel() -> Result<()> {
    Ok(())
 }

-/// Install a project without a `pyproject.toml`, using the PEP 517 build backend (default).
+/// Install a project without a `pyproject.toml`, using the PEP 517 build backend.
 #[test]
 fn sync_legacy_sdist_pep_517() -> Result<()> {
    let context = TestContext::new("3.12");
@ -2635,32 +2635,6 @@ fn sync_legacy_sdist_pep_517() -> Result<()> {
    Ok(())
 }

-/// Install a project without a `pyproject.toml`, using `setuptools` directly.
-#[test]
-fn sync_legacy_sdist_setuptools() -> Result<()> {
-    let context = TestContext::new("3.12");
-
-    let requirements_in = context.temp_dir.child("requirements.in");
-    requirements_in.write_str("flake8 @ https://files.pythonhosted.org/packages/66/53/3ad4a3b74d609b3b9008a10075c40e7c8909eae60af53623c3888f7a529a/flake8-6.0.0.tar.gz")?;
-
-    uv_snapshot!(context.pip_sync()
-        .arg("requirements.in")
-        .arg("--legacy-setup-py"), @r###"
-    success: true
-    exit_code: 0
-    ----- stdout -----
-
-    ----- stderr -----
-    Resolved 1 package in [TIME]
-    Prepared 1 package in [TIME]
-    Installed 1 package in [TIME]
-     + flake8==6.0.0 (from https://files.pythonhosted.org/packages/66/53/3ad4a3b74d609b3b9008a10075c40e7c8909eae60af53623c3888f7a529a/flake8-6.0.0.tar.gz)
-    "###
-    );
-
-    Ok(())
-}
-
 /// Sync using `--find-links` with a local directory.
 #[test]
 fn find_links() -> Result<()> {
--- a/crates/uv/tests/show_settings.rs
+++ b/crates/uv/tests/show_settings.rs
@ -143,7 +143,6 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -279,7 +278,6 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -416,7 +414,6 @@ fn resolve_uv_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -585,7 +582,6 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -700,7 +696,6 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -847,7 +842,6 @@ fn resolve_pyproject_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1031,7 +1025,6 @@ fn resolve_index_url() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1214,7 +1207,6 @@ fn resolve_index_url() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1375,7 +1367,6 @@ fn resolve_find_links() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1512,7 +1503,6 @@ fn resolve_top_level() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1687,7 +1677,6 @@ fn resolve_top_level() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1845,7 +1834,6 @@ fn resolve_top_level() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -1982,7 +1970,6 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2102,7 +2089,6 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2222,7 +2208,6 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2344,7 +2329,6 @@ fn resolve_user_configuration() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2636,7 +2620,6 @@ fn resolve_poetry_toml() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2807,7 +2790,6 @@ fn resolve_both() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -2970,7 +2952,6 @@ fn resolve_config_file() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: true,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -3185,7 +3166,6 @@ fn resolve_skip_empty() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
@ -3308,7 +3288,6 @@ fn resolve_skip_empty() -> anyhow::Result<()> {
            no_header: false,
            custom_compile_command: None,
            generate_hashes: false,
-            setup_py: Pep517,
            config_setting: ConfigSettings(
                {},
            ),
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@ -3678,8 +3678,6 @@ uv pip compile [OPTIONS] <SRC_FILE>...

 <li><code>subprocess</code>:  Use the <code>keyring</code> command for credential lookup</li>
 </ul>
-</dd><dt><code>--legacy-setup-py</code></dt><dd><p>Use legacy <code>setuptools</code> behavior when building source distributions without a <code>pyproject.toml</code></p>
-
 </dd><dt><code>--link-mode</code> <i>link-mode</i></dt><dd><p>The method to use when installing packages from the global cache.</p>

 <p>This option is only used when building source distributions.</p>
@ -4021,8 +4019,6 @@ uv pip sync [OPTIONS] <SRC_FILE>...

 <li><code>subprocess</code>:  Use the <code>keyring</code> command for credential lookup</li>
 </ul>
-</dd><dt><code>--legacy-setup-py</code></dt><dd><p>Use legacy <code>setuptools</code> behavior when building source distributions without a <code>pyproject.toml</code></p>
-
 </dd><dt><code>--link-mode</code> <i>link-mode</i></dt><dd><p>The method to use when installing packages from the global cache.</p>

 <p>Defaults to <code>clone</code> (also known as Copy-on-Write) on macOS, and <code>hardlink</code> on Linux and Windows.</p>
@ -4320,8 +4316,6 @@ uv pip install [OPTIONS] <PACKAGE|--requirement <REQUIREMENT>|--editable <EDITAB

 <li><code>subprocess</code>:  Use the <code>keyring</code> command for credential lookup</li>
 </ul>
-</dd><dt><code>--legacy-setup-py</code></dt><dd><p>Use legacy <code>setuptools</code> behavior when building source distributions without a <code>pyproject.toml</code></p>
-
 </dd><dt><code>--link-mode</code> <i>link-mode</i></dt><dd><p>The method to use when installing packages from the global cache.</p>

 <p>Defaults to <code>clone</code> (also known as Copy-on-Write) on macOS, and <code>hardlink</code> on Linux and Windows.</p>
--- a/docs/reference/settings.md
+++ b/docs/reference/settings.md
@ -1625,33 +1625,6 @@ use the `keyring` CLI to handle authentication.

 ---

-#### [`legacy-setup-py`](#pip_legacy-setup-py) {: #pip_legacy-setup-py }
-<span id="legacy-setup-py"></span>
-
-Use legacy `setuptools` behavior when building source distributions without a
-`pyproject.toml`.
-
-**Default value**: `false`
-
-**Type**: `bool`
-
-**Example usage**:
-
-=== "pyproject.toml"
-
-    ```toml
-    [tool.uv.pip]
-    legacy-setup-py = true
-    ```
-=== "uv.toml"
-
-    ```toml
-    [pip]
-    legacy-setup-py = true
-    ```
-
---
-
 #### [`link-mode`](#pip_link-mode) {: #pip_link-mode }
 <span id="link-mode"></span>

--- a/uv.schema.json
+++ b/uv.schema.json
@ -721,13 +721,6 @@
            }
          ]
        },
-        "legacy-setup-py": {
-          "description": "Use legacy `setuptools` behavior when building source distributions without a `pyproject.toml`.",
-          "type": [
-            "boolean",
-            "null"
-          ]
-        },
        "link-mode": {
          "description": "The method to use when installing packages from the global cache.\n\nDefaults to `clone` (also known as Copy-on-Write) on macOS, and `hardlink` on Linux and Windows.",
          "anyOf": [