Use portable paths for subdirectories in lock URLs (#8707)

## Summary

We're writing different URLs on Windows vs. Linux because the
subdirectory path is being serialized with a back vs. forward slash.

crates/uv-resolver/src/lock/mod.rs

@@ -3152,9 +3152,15 @@ fn locked_git_url(git_dist: &GitSourceDist) -> Url {
     url.set_query(None);
 
     // Put the subdirectory in the query.
-    if let Some(subdirectory) = git_dist.subdirectory.as_deref().and_then(Path::to_str) {
+    if let Some(subdirectory) = git_dist
+        .subdirectory
+        .as_deref()
+        .map(PortablePath::from)
+        .as_ref()
+        .map(PortablePath::to_string)
+    {
         url.query_pairs_mut()
-            .append_pair("subdirectory", subdirectory);
+            .append_pair("subdirectory", &subdirectory);
     }
 
     // Put the requested reference in the query.

crates/uv/tests/it/lock.rs

@@ -17389,3 +17389,144 @@ fn lock_group_empty_entry_table() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn lock_transitive_git() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "a"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["c"]
+
+        [tool.uv.sources]
+        c = { git = "https://github.com/astral-sh/workspace-virtual-root-test", subdirectory = "packages/c", rev = "fac39c8d4c5d0ef32744e2bb309bbe34a759fd46" }
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    "###);
+
+    let lock = context.read("uv.lock");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock, @r###"
+        version = 1
+        requires-python = ">=3.12"
+
+        [options]
+        exclude-newer = "2024-03-25T00:00:00Z"
+
+        [[package]]
+        name = "a"
+        version = "0.1.0"
+        source = { virtual = "." }
+        dependencies = [
+            { name = "c" },
+        ]
+
+        [package.metadata]
+        requires-dist = [{ name = "c", git = "https://github.com/astral-sh/workspace-virtual-root-test?subdirectory=packages%2Fc&rev=fac39c8d4c5d0ef32744e2bb309bbe34a759fd46" }]
+
+        [[package]]
+        name = "anyio"
+        version = "4.3.0"
+        source = { registry = "https://pypi.org/simple" }
+        dependencies = [
+            { name = "idna" },
+            { name = "sniffio" },
+        ]
+        sdist = { url = "https://files.pythonhosted.org/packages/db/4d/3970183622f0330d3c23d9b8a5f52e365e50381fd484d08e3285104333d3/anyio-4.3.0.tar.gz", hash = "sha256:f75253795a87df48568485fd18cdd2a3fa5c4f7c5be8e5e36637733fce06fed6", size = 159642 }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/14/fd/2f20c40b45e4fb4324834aea24bd4afdf1143390242c0b33774da0e2e34f/anyio-4.3.0-py3-none-any.whl", hash = "sha256:048e05d0f6caeed70d731f3db756d35dcc1f35747c8c403364a8332c630441b8", size = 85584 },
+        ]
+
+        [[package]]
+        name = "c"
+        version = "1.0.0"
+        source = { git = "https://github.com/astral-sh/workspace-virtual-root-test?subdirectory=packages%2Fc&rev=fac39c8d4c5d0ef32744e2bb309bbe34a759fd46#fac39c8d4c5d0ef32744e2bb309bbe34a759fd46" }
+        dependencies = [
+            { name = "d" },
+        ]
+
+        [[package]]
+        name = "d"
+        version = "1.0.0"
+        source = { git = "https://github.com/astral-sh/workspace-virtual-root-test?subdirectory=packages%2Fd&rev=fac39c8d4c5d0ef32744e2bb309bbe34a759fd46#fac39c8d4c5d0ef32744e2bb309bbe34a759fd46" }
+        dependencies = [
+            { name = "anyio" },
+        ]
+
+        [[package]]
+        name = "idna"
+        version = "3.6"
+        source = { registry = "https://pypi.org/simple" }
+        sdist = { url = "https://files.pythonhosted.org/packages/bf/3f/ea4b9117521a1e9c50344b909be7886dd00a519552724809bb1f486986c2/idna-3.6.tar.gz", hash = "sha256:9ecdbbd083b06798ae1e86adcbfe8ab1479cf864e4ee30fe4e46a003d12491ca", size = 175426 }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/c2/e7/a82b05cf63a603df6e68d59ae6a68bf5064484a0718ea5033660af4b54a9/idna-3.6-py3-none-any.whl", hash = "sha256:c05567e9c24a6b9faaa835c4821bad0590fbb9d5779e7caa6e1cc4978e7eb24f", size = 61567 },
+        ]
+
+        [[package]]
+        name = "sniffio"
+        version = "1.3.1"
+        source = { registry = "https://pypi.org/simple" }
+        sdist = { url = "https://files.pythonhosted.org/packages/a2/87/a6771e1546d97e7e041b6ae58d80074f81b7d5121207425c964ddf5cfdbd/sniffio-1.3.1.tar.gz", hash = "sha256:f4324edc670a0f49750a81b895f35c3adb843cca46f0530f79fc1babb23789dc", size = 20372 }
+        wheels = [
+            { url = "https://files.pythonhosted.org/packages/e9/44/75a9c9421471a6c4805dbf2356f7c181a29c1879239abab1ea2cc8f38b40/sniffio-1.3.1-py3-none-any.whl", hash = "sha256:2f6da418d1f1e0fddd844478f41680e794e6051915791a034ff65e5f100525a2", size = 10235 },
+        ]
+        "###
+        );
+    });
+
+    // Re-run with `--locked`.
+    uv_snapshot!(context.filters(), context.lock().arg("--locked"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    "###);
+
+    // Re-run with `--offline`. We shouldn't need a network connection to validate an
+    // already-correct lockfile with immutable metadata.
+    uv_snapshot!(context.filters(), context.lock().arg("--locked").arg("--offline").arg("--no-cache"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    "###);
+
+    // Install from the lockfile.
+    uv_snapshot!(context.filters(), context.sync().arg("--frozen"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Prepared 5 packages in [TIME]
+    Installed 5 packages in [TIME]
+     + anyio==4.3.0
+     + c==1.0.0 (from git+https://github.com/astral-sh/workspace-virtual-root-test@fac39c8d4c5d0ef32744e2bb309bbe34a759fd46#subdirectory=packages/c)
+     + d==1.0.0 (from git+https://github.com/astral-sh/workspace-virtual-root-test@fac39c8d4c5d0ef32744e2bb309bbe34a759fd46#subdirectory=packages/d)
+     + idna==3.6
+     + sniffio==1.3.1
+    "###);
+
+    Ok(())
+}

crates/uv/tests/it/workspace.rs

@@ -1766,7 +1766,6 @@ fn test_path_hopping() -> Result<()> {
 /// are correctly resolving `d` to a git dependency with a subdirectory and not relative to the
 /// checkout directory.
 #[test]
-#[cfg(not(windows))]
 fn transitive_dep_in_git_workspace_no_root() -> Result<()> {
     let context = TestContext::new("3.12");
 
@@ -1789,7 +1788,6 @@ fn transitive_dep_in_git_workspace_no_root() -> Result<()> {
     let lock1: SourceLock =
         toml::from_str(&fs_err::read_to_string(context.temp_dir.child("uv.lock"))?)?;
 
-    // TODO(charlie): Fails on Windows due to non-portable subdirectory path in URL.
     assert_json_snapshot!(lock1.sources(), @r###"
     {
       "a": {