Split UV_INDEX on all whitespace (#12820)

## Summary
Closes #12806

Split `UV_INDEX` by any whitespace rather than only ASCII 32, which does
not align with the behavior of `PIP_EXTRA_INDEX_URL` and can possibly
lead to difficulties when migrating from pip to uv.

Clap unfortunately does not support passing multiple delimiters, writing
a custom parsing function involved parsing index into a Vec<Vec<Index>>
and flattening it afterwards in order to avoid breaking the --index
command line option.

There might be a prettier solution I overlooked, let me know if there is
anything I should change!

crates/uv-cli/src/lib.rs

@@ -906,20 +906,27 @@ fn parse_find_links(input: &str) -> Result<Maybe<PipFindLinks>, String> {
     }
 }
 
-/// Parse an `--index` argument into an [`Index`], mapping the empty string to `None`.
+/// Parse an `--index` argument into a [`Vec<Index>`], mapping the empty string to an empty Vec.
-fn parse_index(input: &str) -> Result<Maybe<Index>, String> {
+///
-    if input.is_empty() {
+/// This function splits the input on all whitespace characters rather than a single delimiter,
-        Ok(Maybe::None)
+/// which is necessary to parse environment variables like `PIP_EXTRA_INDEX_URL`.
-    } else {
+/// The standard `clap::Args` `value_delimiter` only supports single-character delimiters.
-        match Index::from_str(input) {
+fn parse_indices(input: &str) -> Result<Vec<Maybe<Index>>, String> {
-            Ok(index) => Ok(Maybe::Some(Index {
+    if input.trim().is_empty() {
+        return Ok(Vec::new());
+    }
+    let mut indices = Vec::new();
+    for token in input.split_whitespace() {
+        match Index::from_str(token) {
+            Ok(index) => indices.push(Maybe::Some(Index {
                 default: false,
                 origin: Some(Origin::Cli),
                 ..index
             })),
-            Err(err) => Err(err.to_string()),
+            Err(e) => return Err(e.to_string()),
         }
     }
+    Ok(indices)
 }
 
 /// Parse a `--default-index` argument into an [`Index`], mapping the empty string to `None`.
@@ -4897,8 +4904,12 @@ pub struct IndexArgs {
     /// All indexes provided via this flag take priority over the index specified by
     /// `--default-index` (which defaults to PyPI). When multiple `--index` flags are provided,
     /// earlier values take priority.
-    #[arg(long, env = EnvVars::UV_INDEX, value_delimiter = ' ', value_parser = parse_index, help_heading = "Index options")]
+    //
-    pub index: Option<Vec<Maybe<Index>>>,
+    // The nested Vec structure (`Vec<Vec<Maybe<Index>>>`) is required for clap's
+    // value parsing mechanism, which processes one value at a time, in order to handle
+    // `UV_INDEX` the same way pip handles `PIP_EXTRA_INDEX_URL`.
+    #[arg(long, env = EnvVars::UV_INDEX, value_parser = parse_indices, help_heading = "Index options")]
+    pub index: Option<Vec<Vec<Maybe<Index>>>>,
 
     /// The URL of the default package index (by default: <https://pypi.org/simple>).
     ///

crates/uv-cli/src/options.rs

@@ -199,9 +199,13 @@ impl From<IndexArgs> for PipOptions {
             index: default_index
                 .and_then(Maybe::into_option)
                 .map(|default_index| vec![default_index])
-                .combine(
+                .combine(index.map(|index| {
-                    index.map(|index| index.into_iter().filter_map(Maybe::into_option).collect()),
+                    index
-                ),
+                        .iter()
+                        .flat_map(std::clone::Clone::clone)
+                        .filter_map(Maybe::into_option)
+                        .collect()
+                })),
             index_url: index_url.and_then(Maybe::into_option),
             extra_index_url: extra_index_url.map(|extra_index_urls| {
                 extra_index_urls
@@ -260,11 +264,13 @@ pub fn resolver_options(
             .default_index
             .and_then(Maybe::into_option)
             .map(|default_index| vec![default_index])
-            .combine(
+            .combine(index_args.index.map(|index| {
-                index_args
+                index
-                    .index
+                    .into_iter()
-                    .map(|index| index.into_iter().filter_map(Maybe::into_option).collect()),
+                    .flat_map(|v| v.clone())
-            ),
+                    .filter_map(Maybe::into_option)
+                    .collect()
+            })),
         index_url: index_args.index_url.and_then(Maybe::into_option),
         extra_index_url: index_args.extra_index_url.map(|extra_index_url| {
             extra_index_url
@@ -352,9 +358,13 @@ pub fn resolver_installer_options(
         .default_index
         .and_then(Maybe::into_option)
         .map(|default_index| vec![default_index]);
-    let index = index_args
+    let index = index_args.index.map(|index| {
-        .index
+        index
-        .map(|index| index.into_iter().filter_map(Maybe::into_option).collect());
+            .into_iter()
+            .flat_map(|v| v.clone())
+            .filter_map(Maybe::into_option)
+            .collect()
+    });
 
     ResolverInstallerOptions {
         index: default_index.combine(index),

crates/uv/src/settings.rs

@@ -1279,6 +1279,7 @@ impl AddSettings {
                     .index
                     .clone()
                     .into_iter()
+                    .flat_map(|v| v.clone())
                     .flatten()
                     .filter_map(Maybe::into_option),
             )

crates/uv/tests/it/edit.rs

@@ -9945,6 +9945,112 @@ fn repeated_index_cli_environment_variable() -> Result<()> {
     Ok(())
 }
 
+/// If an index is repeated on the CLI, the last-provided index should take precedence.
+/// Newlines in `UV_INDEX` should be treated as separators.
+///
+/// The index that appears in the `pyproject.toml` should also be consistent with the index that
+/// appears in the `uv.lock`.
+///
+/// See: <https://github.com/astral-sh/uv/issues/11312>
+#[test]
+fn repeated_index_cli_environment_variable_newline() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! {r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+    "#})?;
+
+    uv_snapshot!(context.filters(), context
+        .add()
+        .env(EnvVars::UV_INDEX, "https://test.pypi.org/simple\nhttps://test.pypi.org/simple/")
+        .arg("iniconfig"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###);
+
+    let pyproject_toml = context.read("pyproject.toml");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            pyproject_toml, @r###"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = [
+            "iniconfig>=2.0.0",
+        ]
+
+        [[tool.uv.index]]
+        url = "https://test.pypi.org/simple"
+        "###
+        );
+    });
+
+    let lock = context.read("uv.lock");
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(
+            lock, @r#"
+        version = 1
+        revision = 1
+        requires-python = ">=3.12"
+
+        [options]
+        exclude-newer = "2024-03-25T00:00:00Z"
+
+        [[package]]
+        name = "iniconfig"
+        version = "2.0.0"
+        source = { registry = "https://test.pypi.org/simple" }
+        sdist = { url = "https://test-files.pythonhosted.org/packages/d7/4b/cbd8e699e64a6f16ca3a8220661b5f83792b3017d0f79807cb8708d33913/iniconfig-2.0.0.tar.gz", hash = "sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3", size = 4646 }
+        wheels = [
+            { url = "https://test-files.pythonhosted.org/packages/ef/a6/62565a6e1cf69e10f5727360368e451d4b7f58beeac6173dc9db836a5b46/iniconfig-2.0.0-py3-none-any.whl", hash = "sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374", size = 5892 },
+        ]
+
+        [[package]]
+        name = "project"
+        version = "0.1.0"
+        source = { virtual = "." }
+        dependencies = [
+            { name = "iniconfig" },
+        ]
+
+        [package.metadata]
+        requires-dist = [{ name = "iniconfig", specifier = ">=2.0.0" }]
+        "#
+        );
+    });
+
+    // Install from the lockfile.
+    uv_snapshot!(context.filters(), context.sync().arg("--frozen"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Audited 1 package in [TIME]
+    "###);
+
+    Ok(())
+}
+
 /// If an index is repeated on the CLI, the last-provided index should take precedence.
 ///
 /// The index that appears in the `pyproject.toml` should also be consistent with the index that