Require --global for removal of the global Python pin (#14169)

While reviewing #14107, @oconnor663
pointed out a bug where we allow `uv python pin --rm` to delete the
global pin without the `--global` flag. I think that shouldn't be
allowed? I'm not 100% certain though.

Author: zanieb

Cargo.lock

@@ -217,6 +217,19 @@ impl PythonVersionFile {
         }
     }
 
+    /// Create a new representation of a global Python version file.
+    ///
+    /// Returns [`None`] if the user configuration directory cannot be determined.
+    pub fn global() -> Option<Self> {
+        let path = user_uv_config_dir()?.join(PYTHON_VERSION_FILENAME);
+        Some(Self::new(path))
+    }
+
+    /// Returns `true` if the version file is a global version file.
+    pub fn is_global(&self) -> bool {
+        PythonVersionFile::global().is_some_and(|global| self.path() == global.path())
+    }
+
     /// Return the first request declared in the file, if any.
     pub fn version(&self) -> Option<&PythonRequest> {
         self.versions.first()
@@ -260,6 +273,9 @@ impl PythonVersionFile {
     /// Update the version file on the file system.
     pub async fn write(&self) -> Result<(), std::io::Error> {
         debug!("Writing Python versions to `{}`", self.path.display());
+        if let Some(parent) = self.path.parent() {
+            fs_err::tokio::create_dir_all(parent).await?;
+        }
         fs::tokio::write(
             &self.path,
             self.versions

crates/uv-python/src/version_files.rs

@@ -24,7 +24,6 @@ uv-cli = { workspace = true }
 uv-client = { workspace = true }
 uv-configuration = { workspace = true }
 uv-console = { workspace = true }
-uv-dirs = { workspace = true }
 uv-dispatch = { workspace = true }
 uv-distribution = { workspace = true }
 uv-distribution-filename = { workspace = true }

crates/uv/Cargo.toml

@@ -9,7 +9,6 @@ use tracing::debug;
 use uv_cache::Cache;
 use uv_client::BaseClientBuilder;
 use uv_configuration::{DependencyGroupsWithDefaults, PreviewMode};
-use uv_dirs::user_uv_config_dir;
 use uv_fs::Simplified;
 use uv_python::{
     EnvironmentPreference, PYTHON_VERSION_FILENAME, PythonDownloads, PythonInstallation,
@@ -72,10 +71,20 @@ pub(crate) async fn pin(
             }
             bail!("No Python version file found");
         };
+
+        if !global && file.is_global() {
+            bail!("No Python version file found; use `--rm --global` to remove the global pin");
+        }
+
         fs_err::tokio::remove_file(file.path()).await?;
         writeln!(
             printer.stdout(),
-            "Removed Python version file at `{}`",
+            "Removed {} at `{}`",
+            if global {
+                "global Python pin"
+            } else {
+                "Python version file"
+            },
             file.path().user_display()
         )?;
         return Ok(ExitStatus::Success);
@@ -194,12 +203,11 @@ pub(crate) async fn pin(
     let existing = version_file.ok().flatten();
     // TODO(zanieb): Allow updating the discovered version file with an `--update` flag.
     let new = if global {
-        let Some(config_dir) = user_uv_config_dir() else {
-            return Err(anyhow::anyhow!("No user-level config directory found."));
+        let Some(new) = PythonVersionFile::global() else {
+            // TODO(zanieb): We should find a nice way to surface that as an error
+            bail!("Failed to determine directory for global Python pin");
         };
-        fs_err::tokio::create_dir_all(&config_dir).await?;
-        PythonVersionFile::new(config_dir.join(PYTHON_VERSION_FILENAME))
-            .with_versions(vec![request])
+        new.with_versions(vec![request])
     } else {
         PythonVersionFile::new(project_dir.join(PYTHON_VERSION_FILENAME))
             .with_versions(vec![request])

crates/uv/src/commands/python/pin.rs

@@ -847,7 +847,7 @@ fn python_pin_rm() {
     error: No Python version file found
     ");
 
-    // Remove the local pin
+    // Create and remove a local pin
     context.python_pin().arg("3.12").assert().success();
     uv_snapshot!(context.filters(), context.python_pin().arg("--rm"), @r"
     success: true
@@ -884,12 +884,41 @@ fn python_pin_rm() {
         .arg("--global")
         .assert()
         .success();
+
     uv_snapshot!(context.filters(), context.python_pin().arg("--rm").arg("--global"), @r"
     success: true
     exit_code: 0
     ----- stdout -----
-    Removed Python version file at `[UV_USER_CONFIG_DIR]/.python-version`
+    Removed global Python pin at `[UV_USER_CONFIG_DIR]/.python-version`
+
+    ----- stderr -----
+    ");
+
+    // Add the global pin again
+    context
+        .python_pin()
+        .arg("3.12")
+        .arg("--global")
+        .assert()
+        .success();
+
+    // Remove the local pin
+    uv_snapshot!(context.filters(), context.python_pin().arg("--rm"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    Removed Python version file at `.python-version`
+
+    ----- stderr -----
+    ");
+
+    // The global pin should not be removed without `--global`
+    uv_snapshot!(context.filters(), context.python_pin().arg("--rm"), @r"
+    success: false
+    exit_code: 2
+    ----- stdout -----
 
     ----- stderr -----
+    error: No Python version file found; use `--rm --global` to remove the global pin
     ");
 }