Add implicit indexes

crates/distribution-types/src/index_source.rs

@@ -0,0 +1,70 @@
+use crate::IndexUrl;
+
+#[derive(Debug, Clone, Hash, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct IndexSource {
+    /// The name of the index.
+    ///
+    /// Index names can be used to reference indexes elsewhere in the configuration. For example,
+    /// you can pin a package to a specific index by name:
+    ///
+    /// ```toml
+    /// [[tool.uv.index]]
+    /// name = "pytorch"
+    /// index = "https://download.pytorch.org/whl/cu121"
+    ///
+    /// [tool.uv.sources]
+    /// torch = { index = "pytorch" }
+    /// ```
+    pub name: Option<String>,
+    /// The URL of the index.
+    ///
+    /// Expects to receive a URL (e.g., `https://pypi.org/simple`) or a local path.
+    pub url: IndexUrl,
+    /// The type of the index.
+    ///
+    /// Indexes can either be PEP 503-compliant (i.e., a registry implementing the Simple API) or
+    /// structured as a flat list of distributions (e.g., `--find-links`). In both cases, indexes
+    /// can point to either local or remote resources.
+    #[serde(default)]
+    pub r#type: IndexKind,
+    /// Mark the index as explicit.
+    ///
+    /// Explicit indexes will _only_ be used when explicitly enabled via a `[tool.uv.sources]`
+    /// definition, as in:
+    ///
+    /// ```toml
+    /// [[tool.uv.index]]
+    /// name = "pytorch"
+    /// index = "https://download.pytorch.org/whl/cu121"
+    /// explicit = true
+    ///
+    /// [tool.uv.sources]
+    /// torch = { index = "pytorch" }
+    /// ```
+    #[serde(default)]
+    pub explicit: bool,
+    /// Mark the index as the default index.
+    ///
+    /// By default, uv uses PyPI as the default index, such that even if additional indexes are
+    /// defined via `[[tool.uv.index]]`, PyPI will still be used as a fallback for packages that
+    /// aren't found elsewhere. To disable the PyPI default, set `default = true` on at least one
+    /// other index.
+    ///
+    /// Marking an index as default will move it to the front of the list of indexes, such that it
+    /// is given the highest priority when resolving packages.
+    #[serde(default)]
+    pub default: bool,
+}
+
+#[derive(
+    Default, Debug, Copy, Clone, Hash, Eq, PartialEq, serde::Serialize, serde::Deserialize,
+)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub enum IndexKind {
+    /// A PEP 503 and/or PEP 691-compliant index.
+    #[default]
+    Simple,
+    /// An index containing a list of links to distributions (e.g., `--find-links`).
+    Flat,
+}

crates/distribution-types/src/index_url.rs

@@ -297,7 +297,7 @@ impl From<VerbatimUrl> for FlatIndexLocation {
 /// The index locations to use for fetching packages. By default, uses the PyPI index.
 ///
 /// From a pip perspective, this type merges `--index-url`, `--extra-index-url`, and `--find-links`.
-#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
+#[derive(Default, Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
 #[serde(rename_all = "kebab-case", deny_unknown_fields)]
 pub struct IndexLocations {
     sources: Vec<IndexSource>,
@@ -307,19 +307,6 @@ pub struct IndexLocations {
     no_index: bool,
 }
 
-impl Default for IndexLocations {
-    /// By default, use the `PyPI` index.
-    fn default() -> Self {
-        Self {
-            sources: Vec::new(),
-            index: Some(DEFAULT_INDEX_URL.clone()),
-            extra_index: Vec::new(),
-            flat_index: Vec::new(),
-            no_index: false,
-        }
-    }
-}
-
 impl IndexLocations {
     /// Determine the index URLs to use for fetching packages.
     pub fn new(
@@ -365,15 +352,32 @@ impl IndexLocations {
     /// Returns `true` if no index configuration is set, i.e., the [`IndexLocations`] matches the
     /// default configuration.
     pub fn is_none(&self) -> bool {
-        self.sources.is_empty()
-            && self.index.is_none()
-            && self.extra_index.is_empty()
-            && self.flat_index.is_empty()
-            && !self.no_index
+        *self == Self::default()
     }
 }
 
 impl<'a> IndexLocations {
+    /// Return an iterator over the `tool.uv.index` sources, prioritizing the default index.
+    fn sources(&'a self) -> impl Iterator<Item = &'a IndexUrl> + 'a {
+        if self.no_index {
+            Either::Left(std::iter::empty())
+        } else {
+            Either::Right(
+                self.sources
+                    .iter()
+                    .filter(|source| !source.explicit)
+                    .filter(|source| source.default)
+                    .chain(
+                        self.sources
+                            .iter()
+                            .filter(|source| !source.explicit)
+                            .filter(|source| !source.default),
+                    )
+                    .map(|source| &source.url),
+            )
+        }
+    }
+
     /// Return the primary [`IndexUrl`] entry.
     ///
     /// If `--no-index` is set, return `None`.
@@ -385,6 +389,7 @@ impl<'a> IndexLocations {
         } else {
             match self.index.as_ref() {
                 Some(index) => Some(index),
+                None if self.sources.iter().any(|source| source.default) => None,
                 None => Some(&DEFAULT_INDEX_URL),
             }
         }
@@ -401,7 +406,7 @@ impl<'a> IndexLocations {
 
     /// Return an iterator over all [`IndexUrl`] entries.
     pub fn indexes(&'a self) -> impl Iterator<Item = &'a IndexUrl> + 'a {
-        self.index().into_iter().chain(self.extra_index())
+        self.sources().chain(self.extra_index()).chain(self.index())
     }
 
     /// Return an iterator over the [`FlatIndexLocation`] entries.
@@ -428,43 +433,40 @@ impl<'a> IndexLocations {
     pub fn urls(&'a self) -> impl Iterator<Item = &'a Url> + 'a {
         self.indexes()
             .map(IndexUrl::url)
-            .chain(self.flat_index.iter().filter_map(|index| match index {
-                FlatIndexLocation::Path(_) => None,
-                FlatIndexLocation::Url(url) => Some(url.raw()),
-            }))
+            .chain(self.flat_index().map(FlatIndexLocation::url))
     }
 }
 
 /// The index URLs to use for fetching packages.
 ///
 /// From a pip perspective, this type merges `--index-url` and `--extra-index-url`.
-#[derive(Debug, Clone)]
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct IndexUrls {
     sources: Vec<IndexSource>,
     index: Option<IndexUrl>,
     extra_index: Vec<IndexUrl>,
     no_index: bool,
 }
 
-impl Default for IndexUrls {
-    /// By default, use the `PyPI` index.
-    fn default() -> Self {
-        Self {
-            sources: Vec::new(),
-            index: Some(DEFAULT_INDEX_URL.clone()),
-            extra_index: Vec::new(),
-            no_index: false,
-        }
-    }
-}
-
 impl<'a> IndexUrls {
-    /// Return an iterator over the `tool.uv.index` sources.
+    /// Return an iterator over the `tool.uv.index` sources, prioritizing the default index.
     fn sources(&'a self) -> impl Iterator<Item = &'a IndexUrl> + 'a {
         if self.no_index {
             Either::Left(std::iter::empty())
         } else {
-            Either::Right(self.sources.iter().map(|source| &source.index))
+            Either::Right(
+                self.sources
+                    .iter()
+                    .filter(|source| !source.explicit)
+                    .filter(|source| source.default)
+                    .chain(
+                        self.sources
+                            .iter()
+                            .filter(|source| !source.explicit)
+                            .filter(|source| !source.default),
+                    )
+                    .map(|source| &source.url),
+            )
         }
     }
 
@@ -479,6 +481,7 @@ impl<'a> IndexUrls {
         } else {
             match self.index.as_ref() {
                 Some(index) => Some(index),
+                None if self.sources.iter().any(|source| source.default) => None,
                 None => Some(&DEFAULT_INDEX_URL),
             }
         }
@@ -495,7 +498,8 @@ impl<'a> IndexUrls {
 
     /// Return an iterator over all [`IndexUrl`] entries in order.
     ///
-    /// Prioritizes the extra indexes over the main index.
+    /// Prioritizes the `[tool.uv.index]` definitions over the `--extra-index-url` definitions
+    /// over the `--index-url` definition.
     ///
     /// If `no_index` was enabled, then this always returns an empty
     /// iterator.

crates/distribution-types/src/lib.rs

@@ -56,9 +56,9 @@ pub use crate::error::*;
 pub use crate::file::*;
 pub use crate::hash::*;
 pub use crate::id::*;
+pub use crate::index_source::*;
 pub use crate::index_url::*;
 pub use crate::installed::*;
-pub use crate::named_index::*;
 pub use crate::prioritized_distribution::*;
 pub use crate::resolution::*;
 pub use crate::resolved::*;
@@ -74,9 +74,9 @@ mod error;
 mod file;
 mod hash;
 mod id;
+mod index_source;
 mod index_url;
 mod installed;
-mod named_index;
 mod prioritized_distribution;
 mod resolution;
 mod resolved;

crates/uv-distribution/src/metadata/lowering.rs

@@ -115,14 +115,15 @@ impl LoweredRequirement {
                 // in that order.
                 let Some(index) = project_indexes
                     .iter()
-                    .find(|IndexSource { name, .. }| *name == index)
+                    .find(|IndexSource { name, .. }| {
+                        name.as_ref().is_some_and(|name| *name == index)
+                    })
                     .or_else(|| {
-                        workspace
-                            .indexes()
-                            .iter()
-                            .find(|IndexSource { name, .. }| *name == index)
+                        workspace.indexes().iter().find(|IndexSource { name, .. }| {
+                            name.as_ref().is_some_and(|name| *name == index)
+                        })
                     })
-                    .map(|IndexSource { index, .. }| index.clone())
+                    .map(|IndexSource { url: index, .. }| index.clone())
                 else {
                     return Err(LoweringError::MissingIndex(requirement.name, index));
                 };
@@ -240,8 +241,10 @@ impl LoweredRequirement {
             Source::Registry { index } => {
                 let Some(index) = indexes
                     .iter()
-                    .find(|IndexSource { name, .. }| *name == index)
-                    .map(|IndexSource { index, .. }| index.clone())
+                    .find(|IndexSource { name, .. }| {
+                        name.as_ref().is_some_and(|name| *name == index)
+                    })
+                    .map(|IndexSource { url: index, .. }| index.clone())
                 else {
                     return Err(LoweringError::MissingIndex(requirement.name, index));
                 };