Handle non-relocatable environments

Author: zanieb

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

@@ -1085,6 +1085,7 @@ hint: If you are running a script with `{}` in the shebang, you may need to incl
                     copy_entrypoint(
                         &entry.path(),
                         &ephemeral_env.scripts().join(entry.file_name()),
+                        &interpreter.sys_executable(),
                         ephemeral_env.sys_executable(),
                     )?;
                 }
@@ -1739,7 +1740,12 @@ fn read_recursion_depth_from_environment_variable() -> anyhow::Result<u32> {
 }
 
 #[cfg(unix)]
-fn copy_entrypoint(source: &Path, target: &Path, python_executable: &Path) -> anyhow::Result<()> {
+fn copy_entrypoint(
+    source: &Path,
+    target: &Path,
+    previous_executable: &Path,
+    python_executable: &Path,
+) -> anyhow::Result<()> {
     use std::os::unix::fs::PermissionsExt;
 
     let contents = fs_err::read_to_string(source)?;
@@ -1749,7 +1755,14 @@ fn copy_entrypoint(source: &Path, target: &Path, python_executable: &Path) -> an
 "#;
 
     // Only rewrite entrypoints that use the expected shebang.
-    let Some(contents) = contents.strip_prefix(expected) else {
+    let Some(contents) = contents
+        .strip_prefix(expected)
+        .or_else(|| contents.strip_prefix(&format!("#!{}", previous_executable.display())))
+    else {
+        debug!(
+            "Skipping copy of entrypoint at {}: does not start with expected shebang",
+            source.user_display()
+        );
         return Ok(());
     };
 
@@ -1770,7 +1783,12 @@ fn copy_entrypoint(source: &Path, target: &Path, python_executable: &Path) -> an
 }
 
 #[cfg(windows)]
-fn copy_entrypoint(source: &Path, target: &Path, python_executable: &Path) -> anyhow::Result<()> {
+fn copy_entrypoint(
+    source: &Path,
+    target: &Path,
+    _previous_executable: &Path,
+    python_executable: &Path,
+) -> anyhow::Result<()> {
     use uv_trampoline_builder::Launcher;
 
     let Some(launcher) = Launcher::try_from_path(source)? else {

crates/uv/tests/it/run.rs

@@ -1319,6 +1319,99 @@ fn run_with_pyvenv_cfg_file() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn run_with_overlay_interpreter() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! { r#"
+        [project]
+        name = "foo"
+        version = "1.0.0"
+        requires-python = ">=3.8"
+        dependencies = []
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+
+        [project.scripts]
+        main = "foo:main"
+        "#
+    })?;
+
+    let foo = context.temp_dir.child("src").child("foo");
+    foo.create_dir_all()?;
+    let init_py = foo.child("__init__.py");
+    init_py.write_str(indoc! { r#"
+        def main():
+            import sys
+            print(sys.executable)
+       "#
+    })?;
+
+    // The project's entrypoint should be rewritten to use the overlay interpreter.
+    uv_snapshot!(context.filters(), context.run().arg("--with").arg("iniconfig").arg("main"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [CACHE_DIR]/builds-v0/[TMP]/python
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + foo==1.0.0 (from file://[TEMP_DIR]/)
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    ");
+
+    // When layering the project on top (via `--with`), the overlay interpreter also should be used.
+    uv_snapshot!(context.filters(), context.run().arg("--no-project").arg("--with").arg(".").arg("main"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [CACHE_DIR]/builds-v0/[TMP]/python
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + foo==1.0.0 (from file://[TEMP_DIR]/)
+    ");
+
+    // Switch to a relocatable virtual environment.
+    context.venv().arg("--relocatable").assert().success();
+
+    // The project's entrypoint should be rewritten to use the overlay interpreter.
+    uv_snapshot!(context.filters(), context.run().arg("--with").arg("iniconfig").arg("main"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [CACHE_DIR]/builds-v0/[TMP]/python
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    Audited 1 package in [TIME]
+    Resolved 1 package in [TIME]
+    ");
+
+    // When layering the project on top (via `--with`), the overlay interpreter also should be used.
+    uv_snapshot!(context.filters(), context.run().arg("--no-project").arg("--with").arg(".").arg("main"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    [CACHE_DIR]/builds-v0/[TMP]/python
+
+    ----- stderr -----
+    Resolved 1 package in [TIME]
+    ");
+
+    Ok(())
+}
+
 #[test]
 fn run_with_build_constraints() -> Result<()> {
     let context = TestContext::new("3.9");