Stabilize sparse-registry

Author: arlosi

src/cargo/core/features.rs

@@ -681,7 +681,7 @@ unstable_cli_options!(
     no_index_update: bool = ("Do not update the registry index even if the cache is outdated"),
     panic_abort_tests: bool = ("Enable support to run tests with -Cpanic=abort"),
     host_config: bool = ("Enable the [host] section in the .cargo/config.toml file"),
-    sparse_registry: bool = ("Support plain-HTTP-based crate registries"),
+    sparse_registry: bool = ("Use the sparse protocol when accessing crates.io"),
     target_applies_to_host: bool = ("Enable the `target-applies-to-host` key in the .cargo/config.toml file"),
     rustdoc_map: bool = ("Allow passing external documentation mappings to rustdoc"),
     separate_nightlies: bool = (HIDDEN),
@@ -749,6 +749,11 @@ const STABILIZED_TIMINGS: &str = "The -Ztimings option has been stabilized as --
 
 const STABILISED_MULTITARGET: &str = "Multiple `--target` options are now always available.";
 
+const STABILISED_SPARSE_REGISTRY: &str = "This flag currently still sets the default protocol\
+    to `sparse` when accessing crates.io. However, this will be removed in the future. \n\
+    The stable equivalent is to set the config value `registries.crates-io.protocol = 'sparse'`\n\
+    or environment variable `CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse`";
+
 fn deserialize_build_std<'de, D>(deserializer: D) -> Result<Option<Vec<String>>, D::Error>
 where
     D: serde::Deserializer<'de>,
@@ -955,7 +960,10 @@ impl CliUnstable {
             "multitarget" => stabilized_warn(k, "1.64", STABILISED_MULTITARGET),
             "rustdoc-map" => self.rustdoc_map = parse_empty(k, v)?,
             "terminal-width" => self.terminal_width = Some(parse_usize_opt(v)?),
-            "sparse-registry" => self.sparse_registry = parse_empty(k, v)?,
+            "sparse-registry" => {
+                stabilized_warn(k, "1.66", STABILISED_SPARSE_REGISTRY);
+                self.sparse_registry = parse_empty(k, v)?;
+            }
             "namespaced-features" => stabilized_warn(k, "1.60", STABILISED_NAMESPACED_FEATURES),
             "weak-dep-features" => stabilized_warn(k, "1.60", STABILIZED_WEAK_DEP_FEATURES),
             "credential-process" => self.credential_process = parse_empty(k, v)?,

src/cargo/sources/registry/http_remote.rs

@@ -131,9 +131,6 @@ impl<'cfg> HttpRegistry<'cfg> {
         config: &'cfg Config,
         name: &str,
     ) -> CargoResult<HttpRegistry<'cfg>> {
-        if !config.cli_unstable().sparse_registry {
-            anyhow::bail!("usage of sparse registries requires `-Z sparse-registry`");
-        }
         let url = source_id.url().as_str();
         // Ensure the url ends with a slash so we can concatenate paths.
         if !url.ends_with('/') {

src/doc/src/reference/config.md

@@ -891,6 +891,13 @@ commands like [`cargo publish`] that require authentication.
 
 Can be overridden with the `--token` command-line option.
 
+##### `registries.crates-io.protocol`
+* Type: string
+* Default: `git`
+* Environment: `CARGO_REGISTRIES_CRATES_IO_PROTOCOL`
+
+Specifies the protocol used to access crates.io. Allowed values are `git` or `sparse`.
+
 #### `[registry]`
 
 The `[registry]` table controls the default registry used when one is not

src/doc/src/reference/registries.md

@@ -19,7 +19,9 @@ table has a key for each registry, for example:
 my-registry = { index = "https://my-intranet:8080/git/index" }
 ```
 
-The `index` key should be a URL to a git repository with the registry's index.
+The `index` key should be a URL to a git repository with the registry's index or a
+Cargo sparse registry URL with the `sparse+` prefix.
+
 A crate can then depend on a crate from another registry by specifying the
 `registry` key and a value of the registry's name in that dependency's entry
 in `Cargo.toml`:
@@ -45,6 +47,21 @@ CARGO_REGISTRIES_MY_REGISTRY_INDEX=https://my-intranet:8080/git/index
 > Note: [crates.io] does not accept packages that depend on crates from other
 > registries.
 
+### Sparse Registries
+Cargo supports two remote registry protocols: `git` and `sparse`. The `git` protocol 
+stores index metadata in a git repository and requires Cargo to clone the entire repo.
+
+The `sparse` protocol fetches individual metadata files using plain HTTP requests.
+Since Cargo only downloads the metadata for relevant crates, the `sparse` protocol can
+save significant time and bandwidth.
+
+Cargo uses the `sparse` protocol for registry URLs that start with the `sparse+` prefix.
+
+The format of a `sparse` index is identical to a checkout of a `git` index.
+
+The protocol used for accessing crates.io can be set via the [`registries.crates-io.protocol`]
+config key.
+
 ### Publishing to an Alternate Registry
 
 If the registry supports web API access, then packages can be published
@@ -660,5 +677,6 @@ browser to log in and retrieve an API token.
 [`cargo publish`]: ../commands/cargo-publish.md
 [alphanumeric]: ../../std/primitive.char.html#method.is_alphanumeric
 [config]: config.md
+[`registries.crates-io.protocol`]: config.md#registriescrates-ioprotocol
 [crates.io]: https://crates.io/
 [publishing documentation]: publishing.md#cargo-owner

src/doc/src/reference/unstable.md

@@ -98,7 +98,6 @@ Each new feature described below should explain how to use it.
 * Registries
     * [credential-process](#credential-process) — Adds support for fetching registry tokens from an external authentication program.
     * [`cargo logout`](#cargo-logout) — Adds the `logout` command to remove the currently saved registry token.
-    * [sparse-registry](#sparse-registry) — Adds support for fetching from static-file HTTP registries (`sparse+`)
 
 ### allow-features
 
@@ -828,19 +827,6 @@ fn main() {
 }
 ```
 
-### sparse-registry
-* Tracking Issue: [9069](https://github.com/rust-lang/cargo/issues/9069)
-* RFC: [#2789](https://github.com/rust-lang/rfcs/pull/2789)
-
-The `sparse-registry` feature allows cargo to interact with remote registries served
-over plain HTTP rather than git. These registries can be identified by urls starting with
-`sparse+http://` or `sparse+https://`.
-
-When fetching index metadata over HTTP, Cargo only downloads the metadata for relevant
-crates, which can save significant time and bandwidth.
-
-The format of the sparse index is identical to a checkout of a git-based index.
-
 ### credential-process
 * Tracking Issue: [#8933](https://github.com/rust-lang/cargo/issues/8933)
 * RFC: [#2730](https://github.com/rust-lang/rfcs/pull/2730)

tests/testsuite/alt_registry.rs

@@ -1314,9 +1314,7 @@ fn sparse_lockfile() {
         .file("src/lib.rs", "")
         .build();
 
-    p.cargo("-Zsparse-registry generate-lockfile")
-        .masquerade_as_nightly_cargo(&["sparse-registry"])
-        .run();
+    p.cargo("generate-lockfile").run();
     assert_match_exact(
         &p.read_lockfile(),
         r#"# This file is automatically @generated by Cargo.