Rename --force to --allow-existing (#3416)

## Summary

We've found `--force` to be a confusing name here. (Not breaking as this
hasn't shipped in a release.)

crates/uv-fs/src/lib.rs

@@ -93,13 +93,12 @@ pub fn replace_symlink(src: impl AsRef<Path>, dst: impl AsRef<Path>) -> std::io:
     match std::os::unix::fs::symlink(src.as_ref(), dst.as_ref()) {
         Ok(()) => Ok(()),
         Err(err) if err.kind() == std::io::ErrorKind::AlreadyExists => {
-            // Create a symlink to the directory store, using a temporary file to ensure atomicity.
+            // Create a symlink, using a temporary file to ensure atomicity.
-            let temp_dir =
+            let temp_dir = tempfile::tempdir_in(dst.as_ref().parent().unwrap())?;
-                tempfile::tempdir_in(dst.as_ref().parent().expect("Cache entry to have parent"))?;
             let temp_file = temp_dir.path().join("link");
             std::os::unix::fs::symlink(src, &temp_file)?;
 
-            // Move the symlink into the wheel cache.
+            // Move the symlink into the target location.
             fs_err::rename(&temp_file, dst.as_ref())?;
 
             Ok(())

crates/uv-virtualenv/src/bare.rs

@@ -49,7 +49,7 @@ pub fn create_bare_venv(
     interpreter: &Interpreter,
     prompt: Prompt,
     system_site_packages: bool,
-    force: bool,
+    allow_existing: bool,
 ) -> Result<VirtualEnvironment, Error> {
     // Determine the base Python executable; that is, the Python executable that should be
     // considered the "base" for the virtual environment. This is typically the Python executable
@@ -91,8 +91,8 @@ pub fn create_bare_venv(
                     format!("File exists at `{}`", location.user_display()),
                 )));
             } else if metadata.is_dir() {
-                if force {
+                if allow_existing {
-                    info!("Overwriting existing directory");
+                    info!("Allowing existing directory");
                 } else if location.join("pyvenv.cfg").is_file() {
                     info!("Removing existing directory");
                     fs::remove_dir_all(location)?;

crates/uv-virtualenv/src/lib.rs

@@ -51,10 +51,16 @@ pub fn create_venv(
     interpreter: Interpreter,
     prompt: Prompt,
     system_site_packages: bool,
-    force: bool,
+    allow_existing: bool,
 ) -> Result<PythonEnvironment, Error> {
     // Create the virtualenv at the given location.
-    let virtualenv = create_bare_venv(location, &interpreter, prompt, system_site_packages, force)?;
+    let virtualenv = create_bare_venv(
+        location,
+        &interpreter,
+        prompt,
+        system_site_packages,
+        allow_existing,
+    )?;
 
     // Create the corresponding `PythonEnvironment`.
     let interpreter = interpreter.with_virtualenv(virtualenv);

crates/uv/src/cli.rs

@@ -1706,14 +1706,17 @@ pub(crate) struct VenvArgs {
     #[arg(long)]
     pub(crate) seed: bool,
 
-    /// Overwrite the directory at the specified path when creating the virtual environment.
+    /// Preserve any existing files or directories at the target path.
     ///
     /// By default, `uv venv` will remove an existing virtual environment at the given path, and
-    /// exit with an error if the path is non-empty but _not_ a virtual environment. The `--force`
+    /// exit with an error if the path is non-empty but _not_ a virtual environment. The
-    /// option will instead write to the given path, regardless of its contents, and without
+    /// `--allow-existing` option will instead write to the given path, regardless of its contents,
-    /// clearing it beforehand.
+    /// and without clearing it beforehand.
+    ///
+    /// WARNING: This option can lead to unexpected behavior if the existing virtual environment
+    /// and the newly-created virtual environment are linked to different Python interpreters.
     #[clap(long)]
-    pub(crate) force: bool,
+    pub(crate) allow_existing: bool,
 
     /// The path to the virtual environment to create.
     #[arg(default_value = ".venv")]

crates/uv/src/commands/venv.rs

@@ -44,7 +44,7 @@ pub(crate) async fn venv(
     system_site_packages: bool,
     connectivity: Connectivity,
     seed: bool,
-    force: bool,
+    allow_existing: bool,
     exclude_newer: Option<ExcludeNewer>,
     native_tls: bool,
     cache: &Cache,
@@ -61,7 +61,7 @@ pub(crate) async fn venv(
         system_site_packages,
         connectivity,
         seed,
-        force,
+        allow_existing,
         exclude_newer,
         native_tls,
         cache,
@@ -109,7 +109,7 @@ async fn venv_impl(
     system_site_packages: bool,
     connectivity: Connectivity,
     seed: bool,
-    force: bool,
+    allow_existing: bool,
     exclude_newer: Option<ExcludeNewer>,
     native_tls: bool,
     cache: &Cache,
@@ -146,7 +146,13 @@ async fn venv_impl(
     .into_diagnostic()?;
 
     // Create the virtual environment.
-    let venv = uv_virtualenv::create_venv(path, interpreter, prompt, system_site_packages, force)
+    let venv = uv_virtualenv::create_venv(
+        path,
+        interpreter,
+        prompt,
+        system_site_packages,
+        allow_existing,
+    )
     .map_err(VenvError::Creation)?;
 
     // Install seed packages.

crates/uv/src/main.rs

@@ -484,7 +484,7 @@ async fn run() -> Result<ExitStatus> {
                 args.system_site_packages,
                 args.shared.connectivity,
                 args.seed,
-                args.force,
+                args.allow_existing,
                 args.shared.exclude_newer,
                 globals.native_tls,
                 &cache,

crates/uv/src/settings.rs

@@ -747,7 +747,7 @@ impl PipCheckSettings {
 pub(crate) struct VenvSettings {
     // CLI-only settings.
     pub(crate) seed: bool,
-    pub(crate) force: bool,
+    pub(crate) allow_existing: bool,
     pub(crate) name: PathBuf,
     pub(crate) prompt: Option<String>,
     pub(crate) system_site_packages: bool,
@@ -764,7 +764,7 @@ impl VenvSettings {
             system,
             no_system,
             seed,
-            force,
+            allow_existing,
             name,
             prompt,
             system_site_packages,
@@ -783,7 +783,7 @@ impl VenvSettings {
         Self {
             // CLI-only settings.
             seed,
-            force,
+            allow_existing,
             name,
             prompt,
             system_site_packages,

crates/uv/tests/venv.rs

@@ -381,11 +381,11 @@ fn non_empty_dir_exists() -> Result<()> {
 }
 
 #[test]
-fn non_empty_dir_exists_force() -> Result<()> {
+fn non_empty_dir_exists_allow_existing() -> Result<()> {
     let context = VenvTestContext::new(&["3.12"]);
 
     // Create a non-empty directory at `.venv`. Creating a virtualenv at the same path should
-    // succeed when `--force` is specified, but fail when it is not.
+    // succeed when `--allow-existing` is specified, but fail when it is not.
     context.venv.create_dir_all()?;
     context.venv.child("file").touch()?;
 
@@ -409,7 +409,7 @@ fn non_empty_dir_exists_force() -> Result<()> {
 
     uv_snapshot!(context.filters(), context.venv_command()
         .arg(context.venv.as_os_str())
-        .arg("--force")
+        .arg("--allow-existing")
         .arg("--python")
         .arg("3.12"), @r###"
     success: true
@@ -427,7 +427,7 @@ fn non_empty_dir_exists_force() -> Result<()> {
     // directories.
     uv_snapshot!(context.filters(), context.venv_command()
         .arg(context.venv.as_os_str())
-        .arg("--force")
+        .arg("--allow-existing")
         .arg("--python")
         .arg("3.12"), @r###"
     success: true