Packages as namespaces part 1 by b-naber · Pull Request #153312 · rust-lang/rust

b-naber · 2026-03-02T22:52:10Z

Part 1 of #152299

r? @petrochenkov

rustbot · 2026-03-02T22:52:14Z

HIR ty lowering was modified

cc @fmease

tests/ui/resolve/open-ns-1.rs

tests/ui/resolve/open-ns-5.rs

tests/ui/resolve/open-ns-8.rs

compiler/rustc_resolve/src/ident.rs

compiler/rustc_hir/src/def.rs

petrochenkov · 2026-03-06T14:35:06Z

compiler/rustc_resolve/src/lib.rs

+                && let sym = Symbol::intern(name)
+                && sym.can_be_raw()
+            {
+                Some((IdentKey::with_root_ctxt(sym), ExternPreludeEntry::flag()))


Names with :: shouldn't be added to the map here, even if they are added they will never be used anyway.

I don't think ScopeSet::NamespacedCrate is necessary.
If only one scope is visited, then none of the ambiguity tracking infra in resolve_ident_in_scope_set is needed, you can just do the extern prelude lookup here directly.

This relates to one of your previous comments. I chose to keep these in the extern prelude, because we use them in resolve_ident_in_module. An alternative would be to keep a map like the namespaced_crate_names field. Keeping them in extern_prelude seems ok to me, given that they are passed via --extern.

#153312 (comment)

compiler/rustc_resolve/src/lib.rs

compiler/rustc_resolve/src/ident.rs

b-naber · 2026-03-09T21:33:51Z

Thanks for the review.

@rustbot ready

petrochenkov · 2026-03-12T13:21:11Z

tests/ui/resolve/open-ns-1.rs

+
+use my_api::root_function;
+use my_api::utils::util;
+//~^ ERROR E0432


Suggested change

//~^ ERROR E0432

//~^ ERROR unresolved import `my_api::utils`

petrochenkov · 2026-03-12T13:22:38Z

tests/ui/resolve/open-ns-11.rs

@@ -0,0 +1,12 @@
+// Tests that namespaced crate names are limited to two segments


Non-relevant copypasted comment.

petrochenkov · 2026-03-12T13:25:16Z

compiler/rustc_hir/src/def.rs

    /// **Belongs to the type namespace.**
    ToolMod,

+    /// The resolution for a virtual module in a namespaced crate. E.g. `my_api`


"Virtual" is still used in a number of comments and variables.

petrochenkov · 2026-03-12T13:56:13Z

compiler/rustc_resolve/src/ident.rs

+                let open_ns_name = format!("{}::{}", sym.as_str(), ident.name);
+                let ns_ident = IdentKey::with_root_ctxt(Symbol::intern(&open_ns_name));
+                match self.extern_prelude_get_flag(ns_ident, ident.span, finalize.is_some()) {
+                    Some(decl) => Ok(decl),


No need for the concatenation above, we can lookup the ident directly and return Ok only if the returned Decl is Res::OpenMod.

petrochenkov · 2026-03-12T13:58:18Z

compiler/rustc_resolve/src/ident.rs

                    }
                    Err(determinacy) => Err(determinacy.into_value()),
                };
+


Nit: unnecessary change.

petrochenkov · 2026-03-12T13:59:00Z

compiler/rustc_resolve/src/lib.rs

+        missing_virtual_bases.into_iter().map(|ident| (ident, ExternPreludeEntry::virtual_flag())),
+    );
+
+    debug!(?extern_prelude);


Nit: could you remove the added debugging logic before merging?

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Mar 2, 2026

rustbot assigned petrochenkov Mar 2, 2026

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b-naber added 2 commits March 3, 2026 18:12

collect namespaced crates

374cd80

add tests

79e7d5e

rust-cloud-vms bot force-pushed the namespaced-crate-names-pt1 branch from a2f2abf to 3031b7d Compare March 3, 2026 18:45

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b-naber added 2 commits March 3, 2026 20:29

resolve namespaced crates with virtual root

bc9556f

bless tests after rebase

a4f7d4d

rust-cloud-vms bot force-pushed the namespaced-crate-names-pt1 branch from 3031b7d to a4f7d4d Compare March 3, 2026 20:29

petrochenkov reviewed Mar 6, 2026

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petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 6, 2026

b-naber added 3 commits March 8, 2026 16:21

add human readable annotations for errors in tests

83cb650

add new tests

3e2573c

address review

5d10d90

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 9, 2026

petrochenkov reviewed Mar 12, 2026

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petrochenkov added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Mar 12, 2026

	//~^ ERROR E0432
	//~^ ERROR unresolved import `my_api::utils`

		@@ -0,0 +1,12 @@
		// Tests that namespaced crate names are limited to two segments

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b-naber commented Mar 2, 2026

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b-naber commented Mar 9, 2026

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