Adds support for packaging workspaces.

Takes local dependencies into account when packaging a workspace. Builds
a temporary package registry to provide local dependencies, and overlays
it on the upstream registry.

This adds `--registry` and `--index` flags to `cargo package`. They act
much like the same arguments to `cargo publish`, except that of course
we are not actually publishing to the specified registry. Instead, these
arguments affect lock-file generation for intra-workspace dependencies:
when simultaneously packaging a crate and one of its dependencies, the
lock-file will be generated under the assumption that the dependency
will be published to the specified registry.

Co-Authored-By: Tor Hovland <55164+torhovland@users.noreply.github.com>

src/bin/cargo/commands/package.rs

@@ -5,6 +5,8 @@ use cargo::ops::{self, PackageOpts};
 pub fn cli() -> Command {
     subcommand("package")
         .about("Assemble the local package into a distributable tarball")
+        .arg_index("Registry index URL to prepare the package for (unstable)")
+        .arg_registry("Registry to prepare the package for (unstable)")
         .arg(
             flag(
                 "list",
@@ -41,6 +43,15 @@ pub fn cli() -> Command {
 }
 
 pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
+    if args._value_of("registry").is_some() {
+        gctx.cli_unstable()
+            .fail_if_stable_opt("--registry", 13947)?;
+    }
+    if args._value_of("index").is_some() {
+        gctx.cli_unstable()
+            .fail_if_stable_opt("--registry", 13947)?;
+    }
+    let reg_or_index = args.registry_or_index(gctx)?;
     let ws = args.workspace(gctx)?;
     if ws.root_maybe().is_embedded() {
         return Err(anyhow::format_err!(
@@ -64,6 +75,7 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
             jobs: args.jobs()?,
             keep_going: args.keep_going(),
             cli_features: args.cli_features()?,
+            reg_or_index,
         },
     )?;
 

src/cargo/core/features.rs

@@ -774,6 +774,7 @@ unstable_cli_options!(
     mtime_on_use: bool = ("Configure Cargo to update the mtime of used files"),
     next_lockfile_bump: bool,
     no_index_update: bool = ("Do not update the registry index even if the cache is outdated"),
+    package_workspace: bool = ("Handle intra-workspace dependencies when packaging"),
     panic_abort_tests: bool = ("Enable support to run tests with -Cpanic=abort"),
     profile_rustflags: bool = ("Enable the `rustflags` option in profiles in .cargo/config.toml file"),
     public_dependency: bool = ("Respect a dependency's `public` field in Cargo.toml to control public/private dependencies"),
@@ -1276,6 +1277,7 @@ impl CliUnstable {
             // can also be set in .cargo/config or with and ENV
             "mtime-on-use" => self.mtime_on_use = parse_empty(k, v)?,
             "no-index-update" => self.no_index_update = parse_empty(k, v)?,
+            "package-workspace" => self.package_workspace= parse_empty(k, v)?,
             "panic-abort-tests" => self.panic_abort_tests = parse_empty(k, v)?,
             "public-dependency" => self.public_dependency = parse_empty(k, v)?,
             "profile-rustflags" => self.profile_rustflags = parse_empty(k, v)?,