Rollup merge of #158207 - LorrensP-2158466:split-resolve-fns, r=petrochenkov

Resolver: local/external split of  `resolve_ident_in_module_non_globs_unadjusted`

This PR splits the function `resolve_ident_in_module_non_globs_unadjusted` into 2 variants:
- one for local modules, which is the same work as before
- other for external modules, which requires less work

In preperations for parallel import resolution and overall resolver refactor.

r? @petrochenkov

Author: jhpratt

compiler/rustc_resolve/src/ident.rs

@@ -23,9 +23,9 @@ use crate::late::{
 use crate::macros::{MacroRulesScope, sub_namespace_match};
 use crate::{
     AmbiguityError, AmbiguityKind, AmbiguityWarning, BindingKey, CmResolver, Decl, DeclKind,
-    Determinacy, Finalize, IdentKey, ImportKind, ImportSummary, LateDecl, LocalModule, Module,
-    ModuleKind, ModuleOrUniformRoot, ParentScope, PathResult, PrivacyError, Res, ResolutionError,
-    Resolver, Scope, ScopeSet, Segment, Stage, Symbol, Used, diagnostics,
+    Determinacy, ExternModule, Finalize, IdentKey, ImportKind, ImportSummary, LateDecl,
+    LocalModule, Module, ModuleKind, ModuleOrUniformRoot, ParentScope, PathResult, PrivacyError,
+    Res, ResolutionError, Resolver, Scope, ScopeSet, Segment, Stage, Symbol, Used, diagnostics,
 };
 
 #[derive(Copy, Clone)]
@@ -608,21 +608,36 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         finalize.map(|f| Finalize { used: Used::Scope, ..f }),
                     )
                 };
-                let decl = self.reborrow().resolve_ident_in_module_non_globs_unadjusted(
-                    module,
-                    ident,
-                    orig_ident_span,
-                    ns,
-                    adjusted_parent_scope,
-                    if matches!(scope_set, ScopeSet::Module(..)) {
-                        Shadowing::Unrestricted
-                    } else {
-                        Shadowing::Restricted
-                    },
-                    adjusted_finalize,
-                    ignore_decl,
-                    ignore_import,
-                );
+                let shadowing = if matches!(scope_set, ScopeSet::Module(..)) {
+                    Shadowing::Unrestricted
+                } else {
+                    Shadowing::Restricted
+                };
+                let decl = if module.is_local() {
+                    self.reborrow().resolve_ident_in_local_module_non_globs_unadjusted(
+                        module.expect_local(),
+                        ident,
+                        orig_ident_span,
+                        ns,
+                        adjusted_parent_scope,
+                        shadowing,
+                        adjusted_finalize,
+                        ignore_decl,
+                        ignore_import,
+                    )
+                } else {
+                    self.reborrow().resolve_ident_in_extern_module_non_globs_unadjusted(
+                        module.expect_extern(),
+                        ident,
+                        orig_ident_span,
+                        ns,
+                        adjusted_parent_scope,
+                        shadowing,
+                        adjusted_finalize,
+                        ignore_decl,
+                    )
+                };
+
                 match decl {
                     Ok(decl) => {
                         if let Some(lint_id) = derive_fallback_lint_id {
@@ -1078,10 +1093,49 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
     }
 
-    /// Attempts to resolve `ident` in namespace `ns` of non-glob bindings in `module`.
-    fn resolve_ident_in_module_non_globs_unadjusted<'r>(
+    /// Attempts to resolve `ident` in namespace `ns` of non-glob bindings in an external `module`.
+    fn resolve_ident_in_extern_module_non_globs_unadjusted<'r>(
         mut self: CmResolver<'r, 'ra, 'tcx>,
-        module: Module<'ra>,
+        module: ExternModule<'ra>,
+        ident: IdentKey,
+        orig_ident_span: Span,
+        ns: Namespace,
+        parent_scope: &ParentScope<'ra>,
+        shadowing: Shadowing,
+        finalize: Option<Finalize>,
+        // This binding should be ignored during in-module resolution, so that we don't get
+        // "self-confirming" import resolutions during import validation and checking.
+        ignore_decl: Option<Decl<'ra>>,
+    ) -> Result<Decl<'ra>, ControlFlow<Determinacy, Determinacy>> {
+        let key = BindingKey::new(ident, ns);
+        let resolution =
+            &*self.resolution(module.to_module(), key).ok_or(ControlFlow::Continue(Determined))?;
+
+        let binding = resolution.non_glob_decl.filter(|b| Some(*b) != ignore_decl);
+
+        if let Some(finalize) = finalize {
+            return self.get_mut().finalize_module_binding(
+                ident,
+                orig_ident_span,
+                binding,
+                parent_scope,
+                finalize,
+                shadowing,
+            );
+        }
+
+        // Items and single imports are not shadowable, if we have one, then it's determined.
+        if let Some(binding) = binding {
+            let accessible = self.is_accessible_from(binding.vis(), parent_scope.module);
+            return if accessible { Ok(binding) } else { Err(ControlFlow::Break(Determined)) };
+        }
+        Err(ControlFlow::Continue(Determined))
+    }
+
+    /// Attempts to resolve `ident` in namespace `ns` of non-glob bindings in a local `module`.
+    fn resolve_ident_in_local_module_non_globs_unadjusted<'r>(
+        mut self: CmResolver<'r, 'ra, 'tcx>,
+        module: LocalModule<'ra>,
         ident: IdentKey,
         orig_ident_span: Span,
         ns: Namespace,
@@ -1098,7 +1152,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // doesn't need to be mutable. It will fail when there is a cycle of imports, and without
         // the exclusive access infinite recursion will crash the compiler with stack overflow.
         let resolution = &*self
-            .resolution_or_default(module, key, orig_ident_span)
+            .resolution_or_default(module.to_module(), key, orig_ident_span)
             .try_borrow_mut_unchecked()
             .map_err(|_| ControlFlow::Continue(Determined))?;
 
@@ -1121,11 +1175,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             return if accessible { Ok(binding) } else { Err(ControlFlow::Break(Determined)) };
         }
 
-        // In extern modules everything is determined from the start.
-        if !module.is_local() {
-            return Err(ControlFlow::Continue(Determined));
-        };
-
         // Check if one of single imports can still define the name, block if it can.
         if self.reborrow().single_import_can_define_name(
             &resolution,