Reinstall and recreate environments when interpreter is removed (#4935)

## Summary

We now recreate the environment in `uv sync`, `uv tool install`, and `uv
tool run` if the underlying interpreter has been removed.

Closes https://github.com/astral-sh/uv/issues/4933.

crates/uv-tool/src/lib.rs

@@ -11,7 +11,7 @@ use std::str::FromStr;
 
 use fs_err::File;
 use thiserror::Error;
-use tracing::debug;
+use tracing::{debug, warn};
 
 use install_wheel_rs::read_record_file;
 
@@ -178,6 +178,9 @@ impl InstalledTools {
     }
 
     /// Return the [`PythonEnvironment`] for a given tool, if it exists.
+    ///
+    /// Returns `Ok(None)` if the environment does not exist or is linked to a non-existent
+    /// interpreter.
     pub fn get_environment(
         &self,
         name: &PackageName,
@@ -186,14 +189,25 @@ impl InstalledTools {
         let _lock = self.acquire_lock();
         let environment_path = self.root.join(name.to_string());
 
-        if environment_path.is_dir() {
-            debug!(
-                "Using existing environment for tool `{name}` at `{}`.",
-                environment_path.user_display()
-            );
-            Ok(Some(PythonEnvironment::from_root(environment_path, cache)?))
-        } else {
-            Ok(None)
+        match PythonEnvironment::from_root(&environment_path, cache) {
+            Ok(venv) => {
+                debug!(
+                    "Using existing environment for tool `{name}`: {}",
+                    environment_path.user_display()
+                );
+                Ok(Some(venv))
+            }
+            Err(uv_python::Error::MissingEnvironment(_)) => Ok(None),
+            Err(uv_python::Error::Query(uv_python::InterpreterError::NotFound(
+                interpreter_path,
+            ))) => {
+                warn!(
+                    "Ignoring existing virtual environment linked to non-existent Python interpreter: {}",
+                    interpreter_path.user_display()
+                );
+                Ok(None)
+            }
+            Err(err) => Err(err.into()),
         }
     }
 
@@ -210,7 +224,7 @@ impl InstalledTools {
         match fs_err::remove_dir_all(&environment_path) {
             Ok(()) => {
                 debug!(
-                    "Removed existing environment for tool `{name}` at `{}`.",
+                    "Removed existing environment for tool `{name}`: {}",
                     environment_path.user_display()
                 );
             }
@@ -219,7 +233,7 @@ impl InstalledTools {
         }
 
         debug!(
-            "Creating environment for tool `{name}` at `{}`.",
+            "Creating environment for tool `{name}`: {}",
             environment_path.user_display()
         );
 

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

@@ -23,6 +23,7 @@ use uv_python::{
 use uv_requirements::{NamedRequirementsResolver, RequirementsSpecification};
 use uv_resolver::{FlatIndex, OptionsBuilder, PythonRequirement, RequiresPython, ResolutionGraph};
 use uv_types::{BuildIsolation, EmptyInstalledPackages, HashStrategy};
+use uv_warnings::warn_user;
 
 use crate::commands::pip::operations::Modifications;
 use crate::commands::reporters::{PythonDownloadReporter, ResolverReporter};
@@ -174,6 +175,12 @@ impl FoundInterpreter {
                 }
             }
             Err(uv_python::Error::MissingEnvironment(_)) => {}
+            Err(uv_python::Error::Query(uv_python::InterpreterError::NotFound(path))) => {
+                warn_user!(
+                    "Ignoring existing virtual environment linked to non-existent Python interpreter: {}",
+                    path.user_display().cyan()
+                );
+            }
             Err(err) => return Err(err.into()),
         };
 

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

@@ -166,9 +166,8 @@ pub(crate) async fn install(
                     } else {
                         let _ = writeln!(
                             printer.stderr(),
-                            "Existing environment for `{}` does not satisfy the requested Python interpreter (`{}`)",
+                            "Existing environment for `{}` does not satisfy the requested Python interpreter",
                             from.name,
-                            python_request
                         );
                         false
                     }

crates/uv/tests/tool_install.rs

@@ -1393,7 +1393,7 @@ fn tool_install_python_request() {
 
     ----- stderr -----
     warning: `uv tool install` is experimental and may change without warning.
-    Existing environment for `black` does not satisfy the requested Python interpreter (`Python 3.11`)
+    Existing environment for `black` does not satisfy the requested Python interpreter
     Resolved [N] packages in [TIME]
     Prepared [N] packages in [TIME]
     Installed [N] packages in [TIME]