Build backend: Add direct builds to the resolver and installer

crates/uv-bench/benches/uv.rs

@@ -87,7 +87,7 @@ mod resolver {
     use uv_client::RegistryClient;
     use uv_configuration::{
         BuildOptions, Concurrency, ConfigSettings, Constraints, IndexStrategy, LowerBound,
-        SourceStrategy,
+        PreviewMode, SourceStrategy,
     };
     use uv_dispatch::{BuildDispatch, SharedState};
     use uv_distribution::DistributionDatabase;
@@ -190,6 +190,7 @@ mod resolver {
             LowerBound::default(),
             sources,
             concurrency,
+            PreviewMode::Enabled,
         );
 
         let markers = if universal {

crates/uv-build-backend/Cargo.toml

@@ -20,6 +20,7 @@ uv-normalize = { workspace = true }
 uv-pep440 = { workspace = true }
 uv-pep508 = { workspace = true }
 uv-pypi-types = { workspace = true }
+uv-version = { workspace = true }
 uv-warnings = { workspace = true }
 
 csv = { workspace = true }

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

@@ -2,7 +2,7 @@ mod metadata;
 mod source_dist;
 mod wheel;
 
-pub use metadata::PyProjectToml;
+pub use metadata::{check_direct_build, PyProjectToml};
 pub use source_dist::{build_source_dist, list_source_dist};
 pub use wheel::{build_editable, build_wheel, list_wheel, metadata};
 

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

@@ -3,6 +3,7 @@ use itertools::Itertools;
 use serde::Deserialize;
 use std::collections::{BTreeMap, Bound};
 use std::ffi::OsStr;
+use std::fmt::Display;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use tracing::{debug, trace};
@@ -50,6 +51,41 @@ pub enum ValidationError {
     InvalidSpdx(String, #[source] spdx::error::ParseError),
 }
 
+/// Check if the build backend is matching the currently running uv version.
+pub fn check_direct_build(source_tree: &Path, name: impl Display) -> bool {
+    let pyproject_toml: PyProjectToml =
+        match fs_err::read_to_string(source_tree.join("pyproject.toml"))
+            .map_err(|err| err.to_string())
+            .and_then(|pyproject_toml| {
+                toml::from_str(&pyproject_toml).map_err(|err| err.to_string())
+            }) {
+            Ok(pyproject_toml) => pyproject_toml,
+            Err(err) => {
+                debug!(
+                    "Not using uv build backend direct build of {name}, no pyproject.toml: {err}"
+                );
+                return false;
+            }
+        };
+    match pyproject_toml
+        .check_build_system(uv_version::version())
+        .as_slice()
+    {
+        // No warnings -> match
+        [] => true,
+        // Any warning -> no match
+        [first, others @ ..] => {
+            debug!(
+                "Not using uv build backend direct build of {name}, pyproject.toml does not match: {first}"
+            );
+            for other in others {
+                trace!("Further uv build backend direct build of {name} mismatch: {other}");
+            }
+            false
+        }
+    }
+}
+
 /// A `pyproject.toml` as specified in PEP 517.
 #[derive(Deserialize, Debug, Clone)]
 #[serde(

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

@@ -251,7 +251,7 @@ impl SourceBuild {
         interpreter: &Interpreter,
         build_context: &impl BuildContext,
         source_build_context: SourceBuildContext,
-        version_id: Option<String>,
+        version_id: Option<&str>,
         locations: &IndexLocations,
         source_strategy: SourceStrategy,
         config_settings: ConfigSettings,
@@ -376,7 +376,7 @@ impl SourceBuild {
                 build_context,
                 package_name.as_ref(),
                 package_version.as_ref(),
-                version_id.as_deref(),
+                version_id,
                 locations,
                 source_strategy,
                 build_kind,
@@ -401,7 +401,7 @@ impl SourceBuild {
             metadata_directory: None,
             package_name,
             package_version,
-            version_id,
+            version_id: version_id.map(ToString::to_string),
             environment_variables,
             modified_path,
             runner,

crates/uv-dispatch/Cargo.toml

@@ -17,11 +17,13 @@ doctest = false
 workspace = true
 
 [dependencies]
+uv-build-backend = { workspace = true }
 uv-build-frontend = { workspace = true }
 uv-cache = { workspace = true }
 uv-client = { workspace = true }
 uv-configuration = { workspace = true }
 uv-distribution = { workspace = true }
+uv-distribution-filename = { workspace = true }
 uv-distribution-types = { workspace = true }
 uv-git = { workspace = true }
 uv-install-wheel = { workspace = true }
@@ -30,9 +32,11 @@ uv-pypi-types = { workspace = true }
 uv-python = { workspace = true }
 uv-resolver = { workspace = true }
 uv-types = { workspace = true }
+uv-version = { workspace = true }
 
 anyhow = { workspace = true }
 futures = { workspace = true }
 itertools = { workspace = true }
 rustc-hash = { workspace = true }
+tokio = { workspace = true }
 tracing = { workspace = true }

crates/uv-dispatch/src/lib.rs

@@ -9,17 +9,18 @@ use anyhow::{anyhow, Context, Result};
 use futures::FutureExt;
 use itertools::Itertools;
 use rustc_hash::FxHashMap;
-use tracing::{debug, instrument};
-
+use tracing::{debug, instrument, trace};
+use uv_build_backend::check_direct_build;
 use uv_build_frontend::{SourceBuild, SourceBuildContext};
 use uv_cache::Cache;
 use uv_client::RegistryClient;
 use uv_configuration::{
-    BuildKind, BuildOptions, ConfigSettings, Constraints, IndexStrategy, LowerBound, Reinstall,
-    SourceStrategy,
+    BuildKind, BuildOptions, ConfigSettings, Constraints, IndexStrategy, LowerBound, PreviewMode,
+    Reinstall, SourceStrategy,
 };
 use uv_configuration::{BuildOutput, Concurrency};
 use uv_distribution::DistributionDatabase;
+use uv_distribution_filename::DistFilename;
 use uv_distribution_types::{
     CachedDist, DependencyMetadata, IndexCapabilities, IndexLocations, Name, Resolution,
     SourceDist, VersionOrUrlRef,
@@ -57,6 +58,7 @@ pub struct BuildDispatch<'a> {
     bounds: LowerBound,
     sources: SourceStrategy,
     concurrency: Concurrency,
+    preview: PreviewMode,
 }
 
 impl<'a> BuildDispatch<'a> {
@@ -79,6 +81,7 @@ impl<'a> BuildDispatch<'a> {
         bounds: LowerBound,
         sources: SourceStrategy,
         concurrency: Concurrency,
+        preview: PreviewMode,
     ) -> Self {
         Self {
             client,
@@ -101,6 +104,7 @@ impl<'a> BuildDispatch<'a> {
             bounds,
             sources,
             concurrency,
+            preview,
         }
     }
 
@@ -340,7 +344,7 @@ impl<'a> BuildContext for BuildDispatch<'a> {
         source: &'data Path,
         subdirectory: Option<&'data Path>,
         install_path: &'data Path,
-        version_id: Option<String>,
+        version_id: Option<&'data str>,
         dist: Option<&'data SourceDist>,
         sources: SourceStrategy,
         build_kind: BuildKind,
@@ -394,6 +398,73 @@ impl<'a> BuildContext for BuildDispatch<'a> {
         .await?;
         Ok(builder)
     }
+
+    async fn direct_build<'data>(
+        &'data self,
+        source: &'data Path,
+        subdirectory: Option<&'data Path>,
+        output_dir: &'data Path,
+        build_kind: BuildKind,
+        version_id: Option<&'data str>,
+    ) -> Result<Option<DistFilename>> {
+        // Direct builds are a preview feature with the uv build backend.
+        if self.preview.is_disabled() {
+            trace!("Preview is disabled, not checking for direct build");
+            return Ok(None);
+        }
+
+        let source_tree = if let Some(subdir) = subdirectory {
+            source.join(subdir)
+        } else {
+            source.to_path_buf()
+        };
+
+        // Only perform the direct build if the backend is uv in a compatible version.
+        let source_tree_str = source_tree.display().to_string();
+        let identifier = version_id.unwrap_or_else(|| &source_tree_str);
+        if !check_direct_build(&source_tree, identifier) {
+            trace!("Requirements for direct build not matched: {identifier}");
+            return Ok(None);
+        }
+
+        debug!("Performing direct build for {identifier}");
+
+        let output_dir = output_dir.to_path_buf();
+        let filename = tokio::task::spawn_blocking(move || -> Result<_> {
+            let filename = match build_kind {
+                BuildKind::Wheel => {
+                    let wheel = uv_build_backend::build_wheel(
+                        &source_tree,
+                        &output_dir,
+                        None,
+                        uv_version::version(),
+                    )?;
+                    DistFilename::WheelFilename(wheel)
+                }
+                BuildKind::Sdist => {
+                    let source_dist = uv_build_backend::build_source_dist(
+                        &source_tree,
+                        &output_dir,
+                        uv_version::version(),
+                    )?;
+                    DistFilename::SourceDistFilename(source_dist)
+                }
+                BuildKind::Editable => {
+                    let wheel = uv_build_backend::build_editable(
+                        &source_tree,
+                        &output_dir,
+                        None,
+                        uv_version::version(),
+                    )?;
+                    DistFilename::WheelFilename(wheel)
+                }
+            };
+            Ok(filename)
+        })
+        .await??;
+
+        Ok(Some(filename))
+    }
 }
 
 /// Shared state used during resolution and installation.

crates/uv-distribution/src/source/mod.rs

@@ -1803,27 +1803,47 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
         fs::create_dir_all(&cache_shard)
             .await
             .map_err(Error::CacheWrite)?;
-        let disk_filename = self
+        // Try a direct build if that isn't disabled and the uv build backend is used.
+        let disk_filename = if let Some(name) = self
             .build_context
-            .setup_build(
+            .direct_build(
                 source_root,
                 subdirectory,
-                source_root,
-                Some(source.to_string()),
-                source.as_dist(),
-                source_strategy,
+                temp_dir.path(),
                 if source.is_editable() {
                     BuildKind::Editable
                 } else {
                     BuildKind::Wheel
                 },
-                BuildOutput::Debug,
+                Some(&source.to_string()),
             )
             .await
             .map_err(Error::Build)?
-            .wheel(temp_dir.path())
-            .await
-            .map_err(Error::Build)?;
+        {
+            // In the uv build backend, the normalized filename and the disk filename are the same.
+            name.to_string()
+        } else {
+            self.build_context
+                .setup_build(
+                    source_root,
+                    subdirectory,
+                    source_root,
+                    Some(&source.to_string()),
+                    source.as_dist(),
+                    source_strategy,
+                    if source.is_editable() {
+                        BuildKind::Editable
+                    } else {
+                        BuildKind::Wheel
+                    },
+                    BuildOutput::Debug,
+                )
+                .await
+                .map_err(Error::Build)?
+                .wheel(temp_dir.path())
+                .await
+                .map_err(Error::Build)?
+        };
 
         // Read the metadata from the wheel.
         let filename = WheelFilename::from_str(&disk_filename)?;
@@ -1884,7 +1904,7 @@ impl<'a, T: BuildContext> SourceDistributionBuilder<'a, T> {
                 source_root,
                 subdirectory,
                 source_root,
-                Some(source.to_string()),
+                Some(&source.to_string()),
                 source.as_dist(),
                 source_strategy,
                 if source.is_editable() {

crates/uv-types/Cargo.toml

@@ -18,6 +18,7 @@ workspace = true
 [dependencies]
 uv-cache = { workspace = true }
 uv-configuration = { workspace = true }
+uv-distribution-filename = { workspace = true }
 uv-distribution-types = { workspace = true }
 uv-git = { workspace = true }
 uv-normalize = { workspace = true }