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 rust-lang#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;
+"#,
+        );
+    }
 }