Merge #7873 #7933

7873: Consider unresolved qualifiers during flyimport r=matklad a=SomeoneToIgnore

Closes https://github.com/rust-analyzer/rust-analyzer/issues/7679

Takes unresolved qualifiers into account, providing better completions (or none, if the path is resolved or do not match).

Does not handle cases when both path qualifier and some trait has to be imported: there are many extra issues with those (such as overlapping imports, for instance) that will require large diffs to address.

Also does not do a fuzzy search on qualifier, that requires some adjustments in `import_map` for better queries and changes to the default replace range which also seems relatively big to include here.

![qualifier_completion](https://user-images.githubusercontent.com/2690773/110040808-0af8dc00-7d4c-11eb-83db-65af94e843bb.gif)


7933: Improve compilation speed r=matklad a=matklad

bors r+
🤖

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>

crates/hir/src/lib.rs

@@ -1114,6 +1114,7 @@ pub enum AssocItem {
     Const(Const),
     TypeAlias(TypeAlias),
 }
+#[derive(Debug)]
 pub enum AssocItemContainer {
     Trait(Trait),
     Impl(Impl),
@@ -2136,6 +2137,16 @@ impl ScopeDef {
     }
 }
 
+impl From<ItemInNs> for ScopeDef {
+    fn from(item: ItemInNs) -> Self {
+        match item {
+            ItemInNs::Types(id) => ScopeDef::ModuleDef(id.into()),
+            ItemInNs::Values(id) => ScopeDef::ModuleDef(id.into()),
+            ItemInNs::Macros(id) => ScopeDef::MacroDef(id.into()),
+        }
+    }
+}
+
 pub trait HasVisibility {
     fn visibility(&self, db: &dyn HirDatabase) -> Visibility;
     fn is_visible_from(&self, db: &dyn HirDatabase, module: Module) -> bool {