Fix name resolution when an import is resolved to some namespace and then later in the algorithm another namespace is added

The import is flagged as "indeterminate", and previously it was re-resolved, but only at the end of name resolution, when it's already too late for anything that depends on it.

This issue was tried to fix in https://github.com/rust-lang/rust-analyzer/pull/2466, but it was not fixed fully.

crates/hir-def/src/nameres/collector.rs

@@ -221,7 +221,7 @@ struct DefCollector<'a> {
     deps: FxHashMap<Name, Dependency>,
     glob_imports: FxHashMap<LocalModuleId, Vec<(LocalModuleId, Visibility, UseId)>>,
     unresolved_imports: Vec<ImportDirective>,
-    indeterminate_imports: Vec<ImportDirective>,
+    indeterminate_imports: Vec<(ImportDirective, PerNs)>,
     unresolved_macros: Vec<MacroDirective>,
     mod_dirs: FxHashMap<LocalModuleId, ModDir>,
     cfg_options: &'a CfgOptions,
@@ -415,16 +415,6 @@ impl DefCollector<'_> {
 
         self.resolution_loop();
 
-        // Resolve all indeterminate resolved imports again
-        // As some of the macros will expand newly import shadowing partial resolved imports
-        // FIXME: We maybe could skip this, if we handle the indeterminate imports in `resolve_imports`
-        // correctly
-        let partial_resolved = self.indeterminate_imports.drain(..).map(|directive| {
-            ImportDirective { status: PartialResolvedImport::Unresolved, ..directive }
-        });
-        self.unresolved_imports.extend(partial_resolved);
-        self.resolve_imports();
-
         let unresolved_imports = mem::take(&mut self.unresolved_imports);
         // show unresolved imports in completion, etc
         for directive in &unresolved_imports {
@@ -749,9 +739,9 @@ impl DefCollector<'_> {
             .filter_map(|mut directive| {
                 directive.status = self.resolve_import(directive.module_id, &directive.import);
                 match directive.status {
-                    PartialResolvedImport::Indeterminate(_) => {
+                    PartialResolvedImport::Indeterminate(resolved) => {
                         self.record_resolved_import(&directive);
-                        self.indeterminate_imports.push(directive);
+                        self.indeterminate_imports.push((directive, resolved));
                         res = ReachedFixedPoint::No;
                         None
                     }
@@ -764,6 +754,33 @@ impl DefCollector<'_> {
                 }
             })
             .collect();
+
+        // Resolve all indeterminate resolved imports again
+        // As some of the macros will expand newly import shadowing partial resolved imports
+        // FIXME: We maybe could skip this, if we handle the indeterminate imports in `resolve_imports`
+        // correctly
+        let mut indeterminate_imports = std::mem::take(&mut self.indeterminate_imports);
+        indeterminate_imports.retain_mut(|(directive, partially_resolved)| {
+            let partially_resolved = partially_resolved.availability();
+            directive.status = self.resolve_import(directive.module_id, &directive.import);
+            match directive.status {
+                PartialResolvedImport::Indeterminate(import)
+                    if partially_resolved != import.availability() =>
+                {
+                    self.record_resolved_import(directive);
+                    res = ReachedFixedPoint::No;
+                    false
+                }
+                PartialResolvedImport::Resolved(_) => {
+                    self.record_resolved_import(directive);
+                    res = ReachedFixedPoint::No;
+                    false
+                }
+                _ => true,
+            }
+        });
+        self.indeterminate_imports = indeterminate_imports;
+
         res
     }
 

crates/hir-def/src/per_ns.rs

@@ -3,6 +3,8 @@
 //!
 //! `PerNs` (per namespace) captures this.
 
+use bitflags::bitflags;
+
 use crate::{
     item_scope::{ImportId, ImportOrExternCrate, ItemInNs},
     visibility::Visibility,
@@ -16,6 +18,16 @@ pub enum Namespace {
     Macros,
 }
 
+bitflags! {
+    /// Describes only the presence/absence of each namespace, without its value.
+    #[derive(Debug, PartialEq, Eq)]
+    pub(crate) struct NsAvailability : u32 {
+        const TYPES = 1 << 0;
+        const VALUES = 1 << 1;
+        const MACROS = 1 << 2;
+    }
+}
+
 #[derive(Clone, Copy, Debug, Default, Eq, Hash, PartialEq)]
 pub struct PerNs {
     pub types: Option<(ModuleDefId, Visibility, Option<ImportOrExternCrate>)>,
@@ -24,6 +36,14 @@ pub struct PerNs {
 }
 
 impl PerNs {
+    pub(crate) fn availability(&self) -> NsAvailability {
+        let mut result = NsAvailability::empty();
+        result.set(NsAvailability::TYPES, self.types.is_some());
+        result.set(NsAvailability::VALUES, self.values.is_some());
+        result.set(NsAvailability::MACROS, self.macros.is_some());
+        result
+    }
+
     pub fn none() -> PerNs {
         PerNs { types: None, values: None, macros: None }
     }

crates/ide/src/goto_definition.rs

@@ -2750,4 +2750,36 @@ fn foo() {
         "#,
         );
     }
+
+    #[test]
+    fn issue_18138() {
+        check(
+            r#"
+mod foo {
+    macro_rules! x {
+        () => {
+            pub struct Foo;
+                    // ^^^
+        };
+    }
+    pub(crate) use x as m;
+}
+
+mod bar {
+    use crate::m;
+
+    m!();
+ // ^^^^^
+
+    fn qux() {
+        Foo$0;
+    }
+}
+
+mod m {}
+
+use foo::m;
+"#,
+        );
+    }
 }