[ty] Make Module::all_submodules return Module instead of Name

This is to facilitate recursive traversal of all modules in an
environment. This way, we can keep asking for submodules.

This also simplifies how this is used in completions, and probably makes
it faster. Namely, since we return the `Module` itself, callers don't
need to invoke the full module resolver just to get the module type.

Note that this doesn't include namespace packages. (Which were
previously not supported in `Module::all_submodules`.) Given how they
can be spread out across multiple search paths, they will likely require
special consideration here.

crates/ty_python_semantic/src/module_resolver/module.rs

@@ -1,9 +1,9 @@
 use std::fmt::Formatter;
 use std::str::FromStr;
 
-use ruff_db::files::File;
-use ruff_python_ast::name::Name;
-use ruff_python_stdlib::identifiers::is_identifier;
+use ruff_db::files::{File, system_path_to_file, vendored_path_to_file};
+use ruff_db::system::SystemPath;
+use ruff_db::vendored::VendoredPath;
 use salsa::Database;
 use salsa::plumbing::AsId;
 
@@ -97,23 +97,10 @@ impl<'db> Module<'db> {
     ///
     /// The names returned correspond to the "base" name of the module.
     /// That is, `{self.name}.{basename}` should give the full module name.
-    pub fn all_submodules(self, db: &'db dyn Db) -> &'db [Name] {
-        self.all_submodules_inner(db).unwrap_or_default()
-    }
-
-    fn all_submodules_inner(self, db: &'db dyn Db) -> Option<&'db [Name]> {
-        // It would be complex and expensive to compute all submodules for
-        // namespace packages, since a namespace package doesn't correspond
-        // to a single file; it can span multiple directories across multiple
-        // search paths. For now, we only compute submodules for traditional
-        // packages that exist in a single directory on a single search path.
-        let Module::File(module) = self else {
-            return None;
-        };
-        if !matches!(module.kind(db), ModuleKind::Package) {
-            return None;
-        }
-        all_submodule_names_for_package(db, module.file(db)).as_deref()
+    pub fn all_submodules(self, db: &'db dyn Db) -> &'db [Module<'db>] {
+        all_submodule_names_for_package(db, self)
+            .as_deref()
+            .unwrap_or_default()
     }
 }
 
@@ -134,7 +121,10 @@ impl std::fmt::Debug for Module<'_> {
 
 #[allow(clippy::ref_option)]
 #[salsa::tracked(returns(ref))]
-fn all_submodule_names_for_package(db: &dyn Db, file: File) -> Option<Vec<Name>> {
+fn all_submodule_names_for_package<'db>(
+    db: &'db dyn Db,
+    module: Module<'db>,
+) -> Option<Vec<Module<'db>>> {
     fn is_submodule(
         is_dir: bool,
         is_file: bool,
@@ -147,7 +137,31 @@ fn all_submodule_names_for_package(db: &dyn Db, file: File) -> Option<Vec<Name>>
                 && !matches!(basename, Some("__init__.py" | "__init__.pyi")))
     }
 
-    let path = SystemOrVendoredPathRef::try_from_file(db, file)?;
+    fn find_package_init_system(db: &dyn Db, dir: &SystemPath) -> Option<File> {
+        system_path_to_file(db, dir.join("__init__.pyi"))
+            .or_else(|_| system_path_to_file(db, dir.join("__init__.py")))
+            .ok()
+    }
+
+    fn find_package_init_vendored(db: &dyn Db, dir: &VendoredPath) -> Option<File> {
+        vendored_path_to_file(db, dir.join("__init__.pyi"))
+            .or_else(|_| vendored_path_to_file(db, dir.join("__init__.py")))
+            .ok()
+    }
+
+    // It would be complex and expensive to compute all submodules for
+    // namespace packages, since a namespace package doesn't correspond
+    // to a single file; it can span multiple directories across multiple
+    // search paths. For now, we only compute submodules for traditional
+    // packages that exist in a single directory on a single search path.
+    let Module::File(module) = module else {
+        return None;
+    };
+    if !matches!(module.kind(db), ModuleKind::Package) {
+        return None;
+    }
+
+    let path = SystemOrVendoredPathRef::try_from_file(db, module.file(db))?;
     debug_assert!(
         matches!(path.file_name(), Some("__init__.py" | "__init__.pyi")),
         "expected package file `{:?}` to be `__init__.py` or `__init__.pyi`",
@@ -189,7 +203,23 @@ fn all_submodule_names_for_package(db: &dyn Db, file: File) -> Option<Vec<Name>>
                 })
                 .filter_map(|entry| {
                     let stem = entry.path().file_stem()?;
-                    is_identifier(stem).then(|| Name::from(stem))
+                    let name = ModuleName::new(stem)?;
+                    let (kind, file) = if entry.file_type().is_directory() {
+                        (
+                            ModuleKind::Package,
+                            find_package_init_system(db, entry.path())?,
+                        )
+                    } else {
+                        let file = system_path_to_file(db, entry.path()).ok()?;
+                        (ModuleKind::Module, file)
+                    };
+                    Some(Module::file_module(
+                        db,
+                        name,
+                        kind,
+                        module.search_path(db).clone(),
+                        file,
+                    ))
                 })
                 .collect()
         }
@@ -209,7 +239,23 @@ fn all_submodule_names_for_package(db: &dyn Db, file: File) -> Option<Vec<Name>>
             })
             .filter_map(|entry| {
                 let stem = entry.path().file_stem()?;
-                is_identifier(stem).then(|| Name::from(stem))
+                let name = ModuleName::new(stem)?;
+                let (kind, file) = if entry.file_type().is_directory() {
+                    (
+                        ModuleKind::Package,
+                        find_package_init_vendored(db, entry.path())?,
+                    )
+                } else {
+                    let file = vendored_path_to_file(db, entry.path()).ok()?;
+                    (ModuleKind::Module, file)
+                };
+                Some(Module::file_module(
+                    db,
+                    name,
+                    kind,
+                    module.search_path(db).clone(),
+                    file,
+                ))
             })
             .collect(),
     })

crates/ty_python_semantic/src/semantic_model.rs

@@ -173,19 +173,10 @@ impl<'db> SemanticModel<'db> {
         let builtin = module.is_known(self.db, KnownModule::Builtins);
 
         let mut completions = vec![];
-        for submodule_basename in module.all_submodules(self.db) {
-            let Some(basename) = ModuleName::new(submodule_basename.as_str()) else {
-                continue;
-            };
-            let mut submodule_name = module.name(self.db).clone();
-            submodule_name.extend(&basename);
-
-            let Some(submodule) = resolve_module(self.db, &submodule_name) else {
-                continue;
-            };
-            let ty = Type::module_literal(self.db, self.file, submodule);
+        for submodule in module.all_submodules(self.db) {
+            let ty = Type::module_literal(self.db, self.file, *submodule);
             completions.push(Completion {
-                name: submodule_basename.clone(),
+                name: Name::new(submodule.name(self.db).as_str()),
                 ty,
                 builtin,
             });