Eagerly reject unsupported Git schemes (#11514)

Initially, we were limiting Git schemes to HTTPS and SSH as only
supported schemes. We lost this validation in #3429. This incidentally
allowed file schemes, which apparently work with Git out of the box.

A caveat for this is that in tool.uv.sources, we parse the git field
always as URL. This caused a problem with #11425: repo = { git =
'c:\path\to\repo', rev = "xxxxx" } was parsed as a URL where c: is the
scheme, causing a bad error message down the line.

This PR:

* Puts Git URL validation back in place. It bans everything but HTTPS,
SSH, and file URLs. This could be a breaking change, if users were using
a git transport protocol were not aware of, even though never
intentionally supported.
* Allows file: URL in Git: This seems to be supported by Git and we were
supporting it albeit unintentionally, so it's reasonable to continue to
support it.
* It does not allow relative paths in the git field in tool.uv.sources.
Absolute file URLs are supported, whether we want relative file URLs for
Git too should be discussed separately.

Closes #3429: We reject the input with a proper error message, while
hinting the user towards file:. If there's still desire for relative
path support, we can keep it open.

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/uv-git-types/src/lib.rs

@@ -1,12 +1,22 @@
 pub use crate::github::GitHubRepository;
 pub use crate::oid::{GitOid, OidParseError};
 pub use crate::reference::GitReference;
+
+use thiserror::Error;
 use url::Url;
 
 mod github;
 mod oid;
 mod reference;
 
+#[derive(Debug, Error)]
+pub enum GitUrlParseError {
+    #[error(
+        "Unsupported Git URL scheme `{0}:` in `{1}` (expected one of `https:`, `ssh:`, or `file:`)"
+    )]
+    UnsupportedGitScheme(String, Url),
+}
+
 /// A URL reference to a Git repository.
 #[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Hash, Ord)]
 pub struct GitUrl {
@@ -21,21 +31,42 @@ pub struct GitUrl {
 
 impl GitUrl {
     /// Create a new [`GitUrl`] from a repository URL and a reference.
-    pub fn from_reference(repository: Url, reference: GitReference) -> Self {
-        Self {
-            repository,
-            reference,
-            precise: None,
-        }
+    pub fn from_reference(
+        repository: Url,
+        reference: GitReference,
+    ) -> Result<Self, GitUrlParseError> {
+        Self::from_fields(repository, reference, None)
     }
 
     /// Create a new [`GitUrl`] from a repository URL and a precise commit.
-    pub fn from_commit(repository: Url, reference: GitReference, precise: GitOid) -> Self {
-        Self {
+    pub fn from_commit(
+        repository: Url,
+        reference: GitReference,
+        precise: GitOid,
+    ) -> Result<Self, GitUrlParseError> {
+        Self::from_fields(repository, reference, Some(precise))
+    }
+
+    /// Create a new [`GitUrl`] from a repository URL and a precise commit, if known.
+    pub fn from_fields(
+        repository: Url,
+        reference: GitReference,
+        precise: Option<GitOid>,
+    ) -> Result<Self, GitUrlParseError> {
+        match repository.scheme() {
+            "https" | "ssh" | "file" => {}
+            unsupported => {
+                return Err(GitUrlParseError::UnsupportedGitScheme(
+                    unsupported.to_string(),
+                    repository,
+                ))
+            }
+        }
+        Ok(Self {
             repository,
             reference,
-            precise: Some(precise),
-        }
+            precise,
+        })
     }
 
     /// Set the precise [`GitOid`] to use for this Git URL.
@@ -69,7 +100,7 @@ impl GitUrl {
 }
 
 impl TryFrom<Url> for GitUrl {
-    type Error = OidParseError;
+    type Error = GitUrlParseError;
 
     /// Initialize a [`GitUrl`] source from a URL.
     fn try_from(mut url: Url) -> Result<Self, Self::Error> {
@@ -89,7 +120,7 @@ impl TryFrom<Url> for GitUrl {
             url.set_path(&prefix);
         }
 
-        Ok(Self::from_reference(url, reference))
+        Self::from_reference(url, reference)
     }
 }