pip compile install a python interpreter when necessary

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

@@ -34,8 +34,8 @@ use uv_normalize::PackageName;
 use uv_preview::{Preview, PreviewFeatures};
 use uv_pypi_types::{Conflicts, SupportedEnvironments};
 use uv_python::{
-    EnvironmentPreference, PythonEnvironment, PythonInstallation, PythonPreference, PythonRequest,
-    PythonVersion, VersionRequest,
+    EnvironmentPreference, PythonDownloads, PythonEnvironment, PythonInstallation,
+    PythonPreference, PythonRequest, PythonVersion, VersionRequest,
 };
 use uv_requirements::upgrade::{LockedRequirements, read_pylock_toml_requirements};
 use uv_requirements::{
@@ -57,6 +57,7 @@ use uv_workspace::pyproject::ExtraBuildDependencies;
 
 use crate::commands::pip::loggers::DefaultResolveLogger;
 use crate::commands::pip::{operations, resolution_markers, resolution_tags};
+use crate::commands::reporters::PythonDownloadReporter;
 use crate::commands::{ExitStatus, OutputWriter, diagnostics};
 use crate::printer::Printer;
 
@@ -109,6 +110,7 @@ pub(crate) async fn pip_compile(
     install_mirrors: PythonInstallMirrors,
     mut python_version: Option<PythonVersion>,
     python_platform: Option<TargetTriple>,
+    python_downloads: PythonDownloads,
     universal: bool,
     exclude_newer: ExcludeNewer,
     sources: SourceStrategy,
@@ -303,14 +305,21 @@ pub(crate) async fn pip_compile(
     .await?;
     let interpreter = if let Some(python) = python.as_ref() {
         let request = PythonRequest::parse(python);
-        PythonInstallation::find(
-            &request,
+        let reporter = PythonDownloadReporter::single(printer);
+        PythonInstallation::find_or_download(
+            Some(&request),
             environment_preference,
             python_preference,
-            &download_list,
+            python_downloads,
+            &client_builder,
             &cache,
+            Some(&reporter),
+            install_mirrors.python_install_mirror.as_deref(),
+            install_mirrors.pypy_install_mirror.as_deref(),
+            install_mirrors.python_downloads_json_url.as_deref(),
             preview,
         )
+        .await
     } else {
         // TODO(zanieb): The split here hints at a problem with the request abstraction; we should
         // be able to use `PythonInstallation::find(...)` here.

crates/uv/src/lib.rs

@@ -645,6 +645,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 args.settings.install_mirrors,
                 args.settings.python_version,
                 args.settings.python_platform,
+                globals.python_downloads,
                 args.settings.universal,
                 args.settings.exclude_newer,
                 args.settings.sources,

crates/uv/tests/it/pip_compile.rs

@@ -1556,28 +1556,32 @@ fn compile_fallback_interpreter() -> Result<()> {
     uv_snapshot!(context.filters(), context.pip_compile()
         .arg("requirements.in")
         .arg("-p")
-        .arg("pypy"), @r###"
+        .arg("pypy"), @r"
     success: false
     exit_code: 2
     ----- stdout -----
 
     ----- stderr -----
     error: No interpreter found for PyPy in [PYTHON SOURCES]
-    "###
+
+    hint: A managed Python download is available for PyPy, but Python downloads are set to 'never'
+    "
     );
 
     // Similarly, we fail if we receive a range request that cannot be satisfied
     uv_snapshot!(context.filters(), context.pip_compile()
             .arg("requirements.in")
             .arg("-p")
-            .arg(">=3.12"), @r###"
+            .arg(">=3.12"), @r"
     success: false
     exit_code: 2
     ----- stdout -----
 
     ----- stderr -----
     error: No interpreter found for Python >=3.12 in [PYTHON SOURCES]
-    "###
+
+    hint: A managed Python download is available for Python >=3.12, but Python downloads are set to 'never'
+    "
     );
 
     Ok(())
@@ -1774,14 +1778,16 @@ fn compile_python_build_version_different_than_target() -> Result<()> {
         .arg("3.12")
         .arg("-p")
         .arg("pypy@3.11")
-        .env_remove(EnvVars::VIRTUAL_ENV), @r###"
+        .env_remove(EnvVars::VIRTUAL_ENV), @r"
     success: false
     exit_code: 2
     ----- stdout -----
 
     ----- stderr -----
     error: No interpreter found for PyPy 3.11 in [PYTHON SOURCES]
-    "###
+
+    hint: A managed Python download is available for PyPy 3.11, but Python downloads are set to 'never'
+    "
     );
 
     uv_snapshot!(context.filters(), context.pip_compile()
@@ -1797,6 +1803,8 @@ fn compile_python_build_version_different_than_target() -> Result<()> {
 
     ----- stderr -----
     error: No interpreter found for Python 3.13 in [PYTHON SOURCES]
+
+    hint: A managed Python download is available for Python 3.13, but Python downloads are set to 'never'
     "
     );
 
@@ -18068,3 +18076,37 @@ fn compile_with_python_platform_and_built_wheel_for_different_platform() -> Resu
 
     Ok(())
 }
+
+#[cfg(feature = "python-managed")]
+#[test]
+fn compile_missing_python() -> Result<()> {
+    let context = TestContext::new("3.12")
+        .with_python_download_cache()
+        .with_managed_python_dirs();
+
+    let requirements_in = context.temp_dir.child("requirements.in");
+    requirements_in.write_str("anyio==3.7.0")?;
+
+    uv_snapshot!(context
+        .pip_compile()
+        .arg("--python").arg("3.13")
+        .arg("--python-version").arg("3.13")
+        .arg("requirements.in"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    # This file was autogenerated by uv via the following command:
+    #    uv pip compile --cache-dir [CACHE_DIR] --python 3.13 --python-version 3.13 requirements.in
+    anyio==3.7.0
+        # via -r requirements.in
+    idna==3.6
+        # via anyio
+    sniffio==1.3.1
+        # via anyio
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    ");
+
+    Ok(())
+}