3 files changed, 40 insertions, 11 deletions

diff --git a/crates/ra_analysis/src/descriptors/module/imp.rs b/crates/ra_analysis/src/descriptors/module/imp.rs
index 1c102f4e5..22dbe7184 100644
--- a/crates/ra_analysis/src/descriptors/module/imp.rs
+++ b/crates/ra_analysis/src/descriptors/module/imp.rs
@@ -14,7 +14,9 @@ use crate::{
     Cancelable, FileId, FileResolverImp,
 };
 
-use super::{LinkData, LinkId, ModuleData, ModuleId, ModuleScope, ModuleTree, Problem};
+use super::{
+    LinkData, LinkId, ModuleData, ModuleId, ModuleScope, ModuleSource, ModuleTree, Problem,
+};
 
 pub(crate) fn submodules(
     db: &impl DescriptorDatabase,
@@ -43,7 +45,7 @@ pub(crate) fn module_scope(
     module_id: ModuleId,
 ) -> Cancelable<Arc<ModuleScope>> {
     let tree = db.module_tree(source_root_id)?;
-    let file_id = module_id.file_id(&tree);
+    let ModuleSource::File(file_id) = module_id.source(&tree);
     let syntax = db.file_syntax(file_id);
     let res = ModuleScope::new(&syntax);
     Ok(Arc::new(res))
@@ -106,7 +108,7 @@ fn build_subtree(
 ) -> Cancelable<ModuleId> {
     visited.insert(file_id);
     let id = tree.push_mod(ModuleData {
-        file_id,
+        source: ModuleSource::File(file_id),
         parent,
         children: Vec::new(),
     });
diff --git a/crates/ra_analysis/src/descriptors/module/mod.rs b/crates/ra_analysis/src/descriptors/module/mod.rs
index 302e3e81c..cbccdb2e2 100644
--- a/crates/ra_analysis/src/descriptors/module/mod.rs
+++ b/crates/ra_analysis/src/descriptors/module/mod.rs
@@ -11,6 +11,13 @@ use crate::FileId;
 
 pub(crate) use self::scope::ModuleScope;
 
+/// Phisically, rust source is organized as a set of files, but logically it is
+/// organized as a tree of modules. Usually, a single file corresponds to a
+/// single module, but it is not nessary the case.
+///
+/// Module encapsulate the logic of transitioning from the fuzzy world of files
+/// (which can have multiple parents) to the precise world of modules (which
+/// always have one parent).
 #[derive(Debug, PartialEq, Eq, Hash)]
 pub(crate) struct ModuleTree {
     mods: Vec<ModuleData>,
@@ -22,7 +29,7 @@ impl ModuleTree {
         self.mods
             .iter()
             .enumerate()
-            .filter(|(_idx, it)| it.file_id == file_id)
+            .filter(|(_idx, it)| it.source.is_file(file_id))
             .map(|(idx, _)| ModuleId(idx as u32))
             .collect()
     }
@@ -50,8 +57,8 @@ pub enum Problem {
 }
 
 impl ModuleId {
-    pub(crate) fn file_id(self, tree: &ModuleTree) -> FileId {
-        tree.module(self).file_id
+    pub(crate) fn source(self, tree: &ModuleTree) -> ModuleSource {
+        tree.module(self).source
     }
     pub(crate) fn parent_link(self, tree: &ModuleTree) -> Option<LinkId> {
         tree.module(self).parent
@@ -110,11 +117,27 @@ impl LinkId {
 
 #[derive(Debug, PartialEq, Eq, Hash)]
 struct ModuleData {
-    file_id: FileId,
+    source: ModuleSource,
     parent: Option<LinkId>,
     children: Vec<LinkId>,
 }
 
+/// `ModuleSource` is the syntax tree element that produced this module:
+/// either a file, or an inlinde module.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub(crate) enum ModuleSource {
+    File(FileId),
+    // Inline(SyntaxPtr),
+}
+
+impl ModuleSource {
+    fn is_file(self, file_id: FileId) -> bool {
+        match self {
+            ModuleSource::File(f) => f == file_id,
+        }
+    }
+}
+
 #[derive(Hash, Debug, PartialEq, Eq)]
 struct LinkData {
     owner: ModuleId,
diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index 0744ea9c8..c1269025c 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -20,7 +20,7 @@ use crate::{
     db::{self, FileSyntaxQuery, SyntaxDatabase},
     descriptors::{
         function::{FnDescriptor, FnId},
-        module::{ModuleTree, Problem},
+        module::{ModuleSource, ModuleTree, Problem},
         DeclarationDescriptor, DescriptorDatabase,
     },
     input::{FilesDatabase, SourceRoot, SourceRootId, WORKSPACE},
@@ -222,7 +222,7 @@ impl AnalysisImpl {
             .into_iter()
             .filter_map(|module_id| {
                 let link = module_id.parent_link(&module_tree)?;
-                let file_id = link.owner(&module_tree).file_id(&module_tree);
+                let ModuleSource::File(file_id) = link.owner(&module_tree).source(&module_tree);
                 let syntax = self.db.file_syntax(file_id);
                 let decl = link.bind_source(&module_tree, syntax.ast());
 
@@ -243,7 +243,9 @@ impl AnalysisImpl {
             .modules_for_file(file_id)
             .into_iter()
             .map(|it| it.root(&module_tree))
-            .map(|it| it.file_id(&module_tree))
+            .map(|it| match it.source(&module_tree) {
+                ModuleSource::File(file_id) => file_id,
+            })
             .filter_map(|it| crate_graph.crate_id_for_crate_root(it))
             .collect();
 
@@ -533,7 +535,9 @@ impl AnalysisImpl {
         };
         module_id
             .child(module_tree, name.as_str())
-            .map(|it| it.file_id(module_tree))
+            .map(|it| match it.source(&module_tree) {
+                ModuleSource::File(file_id) => file_id,
+            })
             .into_iter()
             .collect()
     }