Support no-build-isolation-package (#5894)

## Summary

Resolves #5831 

## Test Plan

`cargo test`

crates/uv-build/src/lib.rs

@@ -434,22 +434,25 @@ impl SourceBuild {
             Self::extract_pep517_backend(&source_tree, setup_py, &default_backend)
                 .map_err(|err| *err)?;
 
+        let package_name = project.clone().map(|p| p.name);
+
         // Create a virtual environment, or install into the shared environment if requested.
-        let venv = match build_isolation {
-            BuildIsolation::Isolated => uv_virtualenv::create_venv(
+        let venv = if let Some(venv) = build_isolation.shared_environment(package_name.as_ref()) {
+            venv.clone()
+        } else {
+            uv_virtualenv::create_venv(
                 temp_dir.path(),
                 interpreter.clone(),
                 uv_virtualenv::Prompt::None,
                 false,
                 false,
                 false,
-            )?,
-            BuildIsolation::Shared(venv) => venv.clone(),
+            )?
         };
 
         // Setup the build environment. If build isolation is disabled, we assume the build
         // environment is already setup.
-        if build_isolation.is_isolated() {
+        if build_isolation.is_isolated(package_name.as_ref()) {
             let resolved_requirements = Self::get_resolved_requirements(
                 build_context,
                 source_build_context,
@@ -499,7 +502,7 @@ impl SourceBuild {
         // Create the PEP 517 build environment. If build isolation is disabled, we assume the build
         // environment is already setup.
         let runner = PythonRunner::new(concurrent_builds);
-        if build_isolation.is_isolated() {
+        if build_isolation.is_isolated(package_name.as_ref()) {
             if let Some(pep517_backend) = &pep517_backend {
                 create_pep517_build_environment(
                     &runner,

crates/uv-cli/src/lib.rs

@@ -3106,6 +3106,12 @@ pub struct ResolverArgs {
     )]
     pub no_build_isolation: bool,
 
+    /// Disable isolation when building source distributions for a specific package.
+    ///
+    /// Assumes that the packages' build dependencies specified by PEP 518  are already installed.
+    #[arg(long, help_heading = "Build options")]
+    pub no_build_isolation_package: Vec<PackageName>,
+
     #[arg(
         long,
         overrides_with("no_build_isolation"),
@@ -3271,6 +3277,12 @@ pub struct ResolverInstallerArgs {
     )]
     pub no_build_isolation: bool,
 
+    /// Disable isolation when building source distributions for a specific package.
+    ///
+    /// Assumes that the packages' build dependencies specified by PEP 518  are already installed.
+    #[arg(long, help_heading = "Build options")]
+    pub no_build_isolation_package: Vec<PackageName>,
+
     #[arg(
         long,
         overrides_with("no_build_isolation"),

crates/uv-cli/src/options.rs

@@ -43,6 +43,7 @@ impl From<ResolverArgs> for PipOptions {
             pre,
             config_setting,
             no_build_isolation,
+            no_build_isolation_package,
             build_isolation,
             exclude_newer,
             link_mode,
@@ -63,6 +64,7 @@ impl From<ResolverArgs> for PipOptions {
             config_settings: config_setting
                 .map(|config_settings| config_settings.into_iter().collect::<ConfigSettings>()),
             no_build_isolation: flag(no_build_isolation, build_isolation),
+            no_build_isolation_package: Some(no_build_isolation_package),
             exclude_newer,
             link_mode,
             no_sources: if no_sources { Some(true) } else { None },
@@ -124,6 +126,7 @@ impl From<ResolverInstallerArgs> for PipOptions {
             pre,
             config_setting,
             no_build_isolation,
+            no_build_isolation_package,
             build_isolation,
             exclude_newer,
             link_mode,
@@ -148,6 +151,7 @@ impl From<ResolverInstallerArgs> for PipOptions {
             config_settings: config_setting
                 .map(|config_settings| config_settings.into_iter().collect::<ConfigSettings>()),
             no_build_isolation: flag(no_build_isolation, build_isolation),
+            no_build_isolation_package: Some(no_build_isolation_package),
             exclude_newer,
             link_mode,
             compile_bytecode: flag(compile_bytecode, no_compile_bytecode),
@@ -195,6 +199,7 @@ pub fn resolver_options(resolver_args: ResolverArgs, build_args: BuildArgs) -> R
         pre,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         build_isolation,
         exclude_newer,
         link_mode,
@@ -237,6 +242,7 @@ pub fn resolver_options(resolver_args: ResolverArgs, build_args: BuildArgs) -> R
         config_settings: config_setting
             .map(|config_settings| config_settings.into_iter().collect::<ConfigSettings>()),
         no_build_isolation: flag(no_build_isolation, build_isolation),
+        no_build_isolation_package: Some(no_build_isolation_package),
         exclude_newer,
         link_mode,
         no_build: flag(no_build, build),
@@ -267,6 +273,7 @@ pub fn resolver_installer_options(
         pre,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         build_isolation,
         exclude_newer,
         link_mode,
@@ -313,6 +320,7 @@ pub fn resolver_installer_options(
         config_settings: config_setting
             .map(|config_settings| config_settings.into_iter().collect::<ConfigSettings>()),
         no_build_isolation: flag(no_build_isolation, build_isolation),
+        no_build_isolation_package: Some(no_build_isolation_package),
         exclude_newer,
         link_mode,
         compile_bytecode: flag(compile_bytecode, no_compile_bytecode),

crates/uv-settings/src/settings.rs

@@ -205,6 +205,7 @@ pub struct ResolverOptions {
     pub no_binary: Option<bool>,
     pub no_binary_package: Option<Vec<PackageName>>,
     pub no_build_isolation: Option<bool>,
+    pub no_build_isolation_package: Option<Vec<PackageName>>,
     pub no_sources: Option<bool>,
 }
 
@@ -350,6 +351,18 @@ pub struct ResolverInstallerOptions {
         "#
     )]
     pub no_build_isolation: Option<bool>,
+    /// Disable isolation when building source distributions for a specific package.
+    ///
+    /// Assumes that the packages' build dependencies specified by [PEP 518](https://peps.python.org/pep-0518/)
+    /// are already installed.
+    #[option(
+        default = "[]",
+        value_type = "Vec<PackageName>",
+        example = r#"
+        no-build-isolation-package = ["package1", "package2"]
+    "#
+    )]
+    pub no_build_isolation_package: Option<Vec<PackageName>>,
     /// Limit candidate packages to those that were uploaded prior to the given date.
     ///
     /// Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
@@ -717,6 +730,18 @@ pub struct PipOptions {
         "#
     )]
     pub no_build_isolation: Option<bool>,
+    /// Disable isolation when building source distributions for a specific package.
+    ///
+    /// Assumes that the packages' build dependencies specified by [PEP 518](https://peps.python.org/pep-0518/)
+    /// are already installed.
+    #[option(
+        default = "[]",
+        value_type = "Vec<PackageName>",
+        example = r#"
+            no-build-isolation-package = ["package1", "package2"]
+        "#
+    )]
+    pub no_build_isolation_package: Option<Vec<PackageName>>,
     /// Validate the Python environment, to detect packages with missing dependencies and other
     /// issues.
     #[option(

crates/uv-types/src/builds.rs

@@ -1,3 +1,4 @@
+use pep508_rs::PackageName;
 use uv_python::PythonEnvironment;
 
 /// Whether to enforce build isolation when building source distributions.
@@ -6,11 +7,33 @@ pub enum BuildIsolation<'a> {
     #[default]
     Isolated,
     Shared(&'a PythonEnvironment),
+    SharedPackage(&'a PythonEnvironment, &'a [PackageName]),
 }
 
 impl<'a> BuildIsolation<'a> {
-    /// Returns `true` if build isolation is enforced.
-    pub fn is_isolated(&self) -> bool {
-        matches!(self, Self::Isolated)
+    /// Returns `true` if build isolation is enforced for the given package name.
+    pub fn is_isolated(&self, package: Option<&PackageName>) -> bool {
+        match self {
+            Self::Isolated => true,
+            Self::Shared(_) => false,
+            Self::SharedPackage(_, packages) => {
+                package.map_or(true, |package| !packages.iter().any(|p| p == package))
+            }
+        }
+    }
+
+    /// Returns the shared environment for a given package, if build isolation is not enforced.
+    pub fn shared_environment(&self, package: Option<&PackageName>) -> Option<&PythonEnvironment> {
+        match self {
+            Self::Isolated => None,
+            Self::Shared(env) => Some(env),
+            Self::SharedPackage(env, packages) => {
+                if package.is_some_and(|package| packages.iter().any(|p| p == package)) {
+                    Some(env)
+                } else {
+                    None
+                }
+            }
+        }
     }
 }

crates/uv/src/commands/pip/compile.rs

@@ -76,6 +76,7 @@ pub(crate) async fn pip_compile(
     config_settings: ConfigSettings,
     connectivity: Connectivity,
     no_build_isolation: bool,
+    no_build_isolation_package: Vec<PackageName>,
     build_options: BuildOptions,
     python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
@@ -303,8 +304,11 @@ pub(crate) async fn pip_compile(
     let build_isolation = if no_build_isolation {
         environment = PythonEnvironment::from_interpreter(interpreter.clone());
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        environment = PythonEnvironment::from_interpreter(interpreter.clone());
+        BuildIsolation::SharedPackage(&environment, &no_build_isolation_package)
     };
 
     let build_dispatch = BuildDispatch::new(

crates/uv/src/commands/pip/install.rs

@@ -3,6 +3,7 @@ use std::fmt::Write;
 use anstream::eprint;
 use itertools::Itertools;
 use owo_colors::OwoColorize;
+use pep508_rs::PackageName;
 use tracing::{debug, enabled, Level};
 
 use distribution_types::{IndexLocations, Resolution, UnresolvedRequirementSpecification};
@@ -59,6 +60,7 @@ pub(crate) async fn pip_install(
     connectivity: Connectivity,
     config_settings: &ConfigSettings,
     no_build_isolation: bool,
+    no_build_isolation_package: Vec<PackageName>,
     build_options: BuildOptions,
     python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
@@ -289,8 +291,10 @@ pub(crate) async fn pip_install(
     // Determine whether to enable build isolation.
     let build_isolation = if no_build_isolation {
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        BuildIsolation::SharedPackage(&environment, &no_build_isolation_package)
     };
 
     // Initialize any shared state.

crates/uv/src/commands/pip/sync.rs

@@ -3,6 +3,7 @@ use std::fmt::Write;
 use anstream::eprint;
 use anyhow::Result;
 use owo_colors::OwoColorize;
+use pep508_rs::PackageName;
 use tracing::debug;
 
 use distribution_types::{IndexLocations, Resolution};
@@ -51,6 +52,7 @@ pub(crate) async fn pip_sync(
     connectivity: Connectivity,
     config_settings: &ConfigSettings,
     no_build_isolation: bool,
+    no_build_isolation_package: Vec<PackageName>,
     build_options: BuildOptions,
     python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
@@ -229,8 +231,10 @@ pub(crate) async fn pip_sync(
     // Determine whether to enable build isolation.
     let build_isolation = if no_build_isolation {
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        BuildIsolation::SharedPackage(&environment, &no_build_isolation_package)
     };
 
     // Initialize any shared state.

crates/uv/src/commands/project/lock.rs

@@ -229,6 +229,7 @@ async fn do_lock(
         prerelease,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         exclude_newer,
         link_mode,
         upgrade,
@@ -298,8 +299,11 @@ async fn do_lock(
     let build_isolation = if no_build_isolation {
         environment = PythonEnvironment::from_interpreter(interpreter.clone());
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        environment = PythonEnvironment::from_interpreter(interpreter.clone());
+        BuildIsolation::SharedPackage(&environment, no_build_isolation_package)
     };
 
     let options = OptionsBuilder::new()

crates/uv/src/commands/project/mod.rs

@@ -406,6 +406,7 @@ pub(crate) async fn resolve_names(
         prerelease: _,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         exclude_newer,
         link_mode,
         compile_bytecode: _,
@@ -436,8 +437,11 @@ pub(crate) async fn resolve_names(
     let build_isolation = if *no_build_isolation {
         environment = PythonEnvironment::from_interpreter(interpreter.clone());
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        environment = PythonEnvironment::from_interpreter(interpreter.clone());
+        BuildIsolation::SharedPackage(&environment, no_build_isolation_package)
     };
 
     // TODO(charlie): These are all default values. We should consider whether we want to make them
@@ -505,6 +509,7 @@ pub(crate) async fn resolve_environment<'a>(
         prerelease,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         exclude_newer,
         link_mode,
         upgrade: _,
@@ -548,8 +553,11 @@ pub(crate) async fn resolve_environment<'a>(
     let build_isolation = if no_build_isolation {
         environment = PythonEnvironment::from_interpreter(interpreter.clone());
         BuildIsolation::Shared(&environment)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        environment = PythonEnvironment::from_interpreter(interpreter.clone());
+        BuildIsolation::SharedPackage(&environment, no_build_isolation_package)
     };
 
     let options = OptionsBuilder::new()
@@ -780,6 +788,7 @@ pub(crate) async fn update_environment(
         prerelease,
         config_setting,
         no_build_isolation,
+        no_build_isolation_package,
         exclude_newer,
         link_mode,
         compile_bytecode,
@@ -848,8 +857,10 @@ pub(crate) async fn update_environment(
     // Determine whether to enable build isolation.
     let build_isolation = if *no_build_isolation {
         BuildIsolation::Shared(&venv)
-    } else {
+    } else if no_build_isolation_package.is_empty() {
         BuildIsolation::Isolated
+    } else {
+        BuildIsolation::SharedPackage(&venv, no_build_isolation_package)
     };
 
     let options = OptionsBuilder::new()