Resolver: Batched Import Resolution

compiler/rustc_hir/src/def.rs

@@ -619,6 +619,24 @@ impl<T> PerNS<T> {
     pub fn iter(&self) -> IntoIter<&T, 3> {
         [&self.value_ns, &self.type_ns, &self.macro_ns].into_iter()
     }
+
+    pub fn into_iter_with(self) -> IntoIter<(Namespace, T), 3> {
+        [
+            (Namespace::TypeNS, self.type_ns),
+            (Namespace::ValueNS, self.value_ns),
+            (Namespace::MacroNS, self.macro_ns),
+        ]
+        .into_iter()
+    }
+
+    pub fn iter_with(&self) -> IntoIter<(Namespace, &T), 3> {
+        [
+            (Namespace::TypeNS, &self.type_ns),
+            (Namespace::ValueNS, &self.value_ns),
+            (Namespace::MacroNS, &self.macro_ns),
+        ]
+        .into_iter()
+    }
 }
 
 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {

compiler/rustc_resolve/src/imports.rs

@@ -2,6 +2,7 @@
 
 use std::cell::Cell;
 use std::mem;
+use std::ops::Deref;
 
 use rustc_ast::NodeId;
 use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
@@ -41,6 +42,90 @@ use crate::{
 
 type Res = def::Res<NodeId>;
 
+pub(crate) struct ImportResolver<'r, 'ra, 'tcx> {
+    r: CmResolver<'r, 'ra, 'tcx>, // always immutable
+    batch: Vec<Import<'ra>>,      // a.k.a. indeterminate_imports, also treated as output
+
+    // outputs
+    determined_imports: Vec<Import<'ra>>,
+    glob_imports: Vec<Import<'ra>>,
+    import_bindings: PerNS<Vec<(Module<'ra>, Import<'ra>, PendingBinding<'ra>)>>,
+}
+
+struct ImportResolutionOutputs<'ra> {
+    indeterminate_imports: Vec<Import<'ra>>,
+    determined_imports: Vec<Import<'ra>>,
+    glob_imports: Vec<Import<'ra>>,
+    import_bindings: PerNS<Vec<(Module<'ra>, Import<'ra>, PendingBinding<'ra>)>>,
+}
+
+impl<'r, 'ra, 'tcx> ImportResolver<'r, 'ra, 'tcx> {
+    pub(crate) fn new(cmr: CmResolver<'r, 'ra, 'tcx>, batch: Vec<Import<'ra>>) -> Self {
+        ImportResolver {
+            r: cmr,
+            batch,
+            determined_imports: Vec::new(),
+            glob_imports: Vec::new(),
+            import_bindings: PerNS::default(),
+        }
+    }
+
+    fn into_outputs(self) -> ImportResolutionOutputs<'ra> {
+        ImportResolutionOutputs {
+            indeterminate_imports: self.batch,
+            determined_imports: self.determined_imports,
+            glob_imports: self.glob_imports,
+            import_bindings: self.import_bindings,
+        }
+    }
+}
+
+impl<'ra> ImportResolutionOutputs<'ra> {
+    fn commit<'tcx>(self, r: &mut Resolver<'ra, 'tcx>) {
+        r.indeterminate_imports = self.indeterminate_imports;
+        r.determined_imports.extend(self.determined_imports);
+
+        for glob in self.glob_imports {
+            r.resolve_glob_import(glob);
+        }
+
+        for (ns, import_bindings) in self.import_bindings.into_iter_with() {
+            for (parent, import, pending_binding) in import_bindings {
+                let ImportKind::Single { target, ref bindings, .. } = import.kind else {
+                    unreachable!();
+                };
+                match pending_binding {
+                    PendingBinding::Ready(Some(binding)) => {
+                        r.define_binding_local(parent, target, ns, binding);
+                    }
+                    PendingBinding::Ready(None) => {
+                        let key = BindingKey::new(target, ns);
+                        r.update_local_resolution(parent, key, false, |_, resolution| {
+                            resolution.single_imports.swap_remove(&import);
+                        });
+                    }
+                    _ => {}
+                }
+                bindings[ns].set(pending_binding);
+            }
+        }
+    }
+}
+
+impl<'r, 'ra, 'tcx> Deref for ImportResolver<'r, 'ra, 'tcx> {
+    type Target = Resolver<'ra, 'tcx>;
+
+    fn deref(&self) -> &Self::Target {
+        self.r.deref()
+    }
+}
+
+impl<'r, 'ra, 'tcx> AsRef<Resolver<'ra, 'tcx>> for ImportResolver<'r, 'ra, 'tcx> {
+    fn as_ref(&self) -> &Resolver<'ra, 'tcx> {
+        self.r.as_ref()
+    }
+}
+
 /// A [`NameBinding`] in the process of being resolved.
 #[derive(Clone, Copy, Default, PartialEq)]
 pub(crate) enum PendingBinding<'ra> {
@@ -552,22 +637,32 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// Resolves all imports for the crate. This method performs the fixed-
     /// point iteration.
     pub(crate) fn resolve_imports(&mut self) {
-        self.assert_speculative = true;
         let mut prev_indeterminate_count = usize::MAX;
         let mut indeterminate_count = self.indeterminate_imports.len() * 3;
         while indeterminate_count < prev_indeterminate_count {
+            self.assert_speculative = true;
             prev_indeterminate_count = indeterminate_count;
-            indeterminate_count = 0;
-            for import in mem::take(&mut self.indeterminate_imports) {
-                let import_indeterminate_count = self.cm().resolve_import(import);
-                indeterminate_count += import_indeterminate_count;
-                match import_indeterminate_count {
-                    0 => self.determined_imports.push(import),
-                    _ => self.indeterminate_imports.push(import),
-                }
+            let batch = mem::take(&mut self.indeterminate_imports);
+            let (outputs, count) = ImportResolver::new(self.cm(), batch).resolve_batch();
+            indeterminate_count = count;
+            self.assert_speculative = false;
+            outputs.commit(self);
+        }
+    }
+
+    fn resolve_batch<'r>(
+        mut self: ImportResolver<'r, 'ra, 'tcx>,
+    ) -> (ImportResolutionOutputs<'ra>, usize) {
+        let mut indeterminate_count = 0;
+        for import in mem::take(&mut self.batch) {
+            let import_indeterminate_count = self.resolve_import(import);
+            indeterminate_count += import_indeterminate_count;
+            match import_indeterminate_count {
+                0 => self.determined_imports.push(import),
+                _ => self.batch.push(import),
             }
         }
-        self.assert_speculative = false;
+        (self.into_outputs(), indeterminate_count)
     }
 
     pub(crate) fn finalize_imports(&mut self) {
@@ -840,7 +935,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     ///
     /// Meanwhile, if resolve successful, the resolved bindings are written
     /// into the module.
-    fn resolve_import<'r>(mut self: CmResolver<'r, 'ra, 'tcx>, import: Import<'ra>) -> usize {
+    fn resolve_import<'r>(self: &mut ImportResolver<'r, 'ra, 'tcx>, import: Import<'ra>) -> usize {
         debug!(
             "(resolving import for module) resolving import `{}::...` in `{}`",
             Segment::names_to_string(&import.module_path),
@@ -849,7 +944,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let module = if let Some(module) = import.imported_module.get() {
             module
         } else {
-            let path_res = self.reborrow().maybe_resolve_path(
+            let path_res = self.r.reborrow().maybe_resolve_path(
                 &import.module_path,
                 None,
                 &import.parent_scope,
@@ -869,16 +964,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 (source, target, bindings, type_ns_only)
             }
             ImportKind::Glob { .. } => {
-                // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                // specualtive resolution.
-                self.get_mut_unchecked().resolve_glob_import(import);
+                self.glob_imports.push(import);
                 return 0;
             }
             _ => unreachable!(),
         };
 
         let mut indeterminate_count = 0;
-        self.per_ns_cm(|this, ns| {
+        self.r.reborrow().per_ns_cm(|this, ns| {
             if !type_ns_only || ns == TypeNS {
                 if bindings[ns].get() != PendingBinding::Pending {
                     return;
@@ -891,7 +984,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     Some(import),
                 );
                 let parent = import.parent_scope.module;
-                let binding = match binding_result {
+                let pending_binding = match binding_result {
                     Ok(binding) => {
                         if binding.is_assoc_item()
                             && !this.tcx.features().import_trait_associated_functions()
@@ -906,39 +999,21 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         }
                         // We need the `target`, `source` can be extracted.
                         let imported_binding = this.import(binding, import);
-                        // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                        // specualtive resolution.
-                        this.get_mut_unchecked().define_binding_local(
-                            parent,
-                            target,
-                            ns,
-                            imported_binding,
-                        );
                         PendingBinding::Ready(Some(imported_binding))
                     }
                     Err(Determinacy::Determined) => {
                         // Don't remove underscores from `single_imports`, they were never added.
-                        if target.name != kw::Underscore {
-                            let key = BindingKey::new(target, ns);
-                            // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                            // specualtive resolution.
-                            this.get_mut_unchecked().update_local_resolution(
-                                parent,
-                                key,
-                                false,
-                                |_, resolution| {
-                                    resolution.single_imports.swap_remove(&import);
-                                },
-                            );
+                        if target.name == kw::Underscore {
+                            return;
                         }
                         PendingBinding::Ready(None)
                     }
                     Err(Determinacy::Undetermined) => {
                         indeterminate_count += 1;
-                        PendingBinding::Pending
+                        return;
                     }
                 };
-                bindings[ns].set(binding);
+                self.import_bindings[ns].push((parent, import, pending_binding));
             }
         });
 

compiler/rustc_resolve/src/lib.rs

@@ -2504,7 +2504,7 @@ mod ref_mut {
 
         /// Returns a mutable reference to the inner value without checking if
         /// it's in a mutable state.
-        pub(crate) fn get_mut_unchecked(&mut self) -> &mut T {
+        pub(crate) fn _get_mut_unchecked(&mut self) -> &mut T {
             self.p
         }
     }

tests/ui/feature-gates/feature-gate-import-trait-associated-functions.stderr

@@ -18,16 +18,6 @@ LL | use A::{DEFAULT, new};
    = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error[E0658]: `use` associated items of traits is unstable
-  --> $DIR/feature-gate-import-trait-associated-functions.rs:7:5
-   |
-LL | use Default::default;
-   |     ^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
-   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0658]: `use` associated items of traits is unstable
   --> $DIR/feature-gate-import-trait-associated-functions.rs:27:26
    |
@@ -58,6 +48,16 @@ LL | use Glob::*;
    = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
+error[E0658]: `use` associated items of traits is unstable
+  --> $DIR/feature-gate-import-trait-associated-functions.rs:7:5
+   |
+LL | use Default::default;
+   |     ^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
+   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
 error: aborting due to 6 previous errors
 
 For more information about this error, try `rustc --explain E0658`.

tests/ui/imports/reexports.stderr

@@ -11,33 +11,33 @@ LL |         pub use super::foo;
    |                 ^^^^^^^^^^
 
 error[E0603]: module import `foo` is private
-  --> $DIR/reexports.rs:36:22
+  --> $DIR/reexports.rs:37:22
    |
-LL |     use crate::b::a::foo::S;
+LL |     use crate::b::b::foo::S as T;
    |                      ^^^ private module import
    |
 note: the module import `foo` is defined here...
-  --> $DIR/reexports.rs:24:17
+  --> $DIR/reexports.rs:29:17
    |
-LL |         pub use super::foo; // This is OK since the value `foo` is visible enough.
-   |                 ^^^^^^^^^^
+LL |         pub use super::*; // This is also OK since the value `foo` is visible enough.
+   |                 ^^^^^^^^
 note: ...and refers to the module `foo` which is defined here
   --> $DIR/reexports.rs:19:5
    |
 LL |     mod foo {
    |     ^^^^^^^
 
 error[E0603]: module import `foo` is private
-  --> $DIR/reexports.rs:37:22
+  --> $DIR/reexports.rs:36:22
    |
-LL |     use crate::b::b::foo::S as T;
+LL |     use crate::b::a::foo::S;
    |                      ^^^ private module import
    |
 note: the module import `foo` is defined here...
-  --> $DIR/reexports.rs:29:17
+  --> $DIR/reexports.rs:24:17
    |
-LL |         pub use super::*; // This is also OK since the value `foo` is visible enough.
-   |                 ^^^^^^^^
+LL |         pub use super::foo; // This is OK since the value `foo` is visible enough.
+   |                 ^^^^^^^^^^
 note: ...and refers to the module `foo` which is defined here
   --> $DIR/reexports.rs:19:5
    |

tests/ui/shadowed/shadowed-use-visibility.stderr

@@ -1,31 +1,31 @@
-error[E0603]: module import `bar` is private
-  --> $DIR/shadowed-use-visibility.rs:9:21
+error[E0603]: module import `f` is private
+  --> $DIR/shadowed-use-visibility.rs:15:10
    |
-LL |     use crate::foo::bar::f as g;
-   |                     ^^^ private module import
+LL | use bar::f::f;
+   |          ^ private module import
    |
-note: the module import `bar` is defined here...
-  --> $DIR/shadowed-use-visibility.rs:4:9
+note: the module import `f` is defined here...
+  --> $DIR/shadowed-use-visibility.rs:11:9
    |
-LL |     use crate::foo as bar;
-   |         ^^^^^^^^^^^^^^^^^
+LL |     use crate::foo as f;
+   |         ^^^^^^^^^^^^^^^
 note: ...and refers to the module `foo` which is defined here
   --> $DIR/shadowed-use-visibility.rs:1:1
    |
 LL | mod foo {
    | ^^^^^^^
 
-error[E0603]: module import `f` is private
-  --> $DIR/shadowed-use-visibility.rs:15:10
+error[E0603]: module import `bar` is private
+  --> $DIR/shadowed-use-visibility.rs:9:21
    |
-LL | use bar::f::f;
-   |          ^ private module import
+LL |     use crate::foo::bar::f as g;
+   |                     ^^^ private module import
    |
-note: the module import `f` is defined here...
-  --> $DIR/shadowed-use-visibility.rs:11:9
+note: the module import `bar` is defined here...
+  --> $DIR/shadowed-use-visibility.rs:4:9
    |
-LL |     use crate::foo as f;
-   |         ^^^^^^^^^^^^^^^
+LL |     use crate::foo as bar;
+   |         ^^^^^^^^^^^^^^^^^
 note: ...and refers to the module `foo` which is defined here
   --> $DIR/shadowed-use-visibility.rs:1:1
    |