Merge #10872

10872: ide_db: build symbol index from crate def map r=Veykril a=jhgg

fixes #4842, #10764

Is this looking correct? 👀 

- [x] build the symbol index based upon the CrateDefMap for the given crate in `crate_symbols`
   - [x] make it multi threaded again, and figure out how to cache each moduleid's symbol index in salsa.
   - [x] NavigationTarget for names in macros is wrong, need to figure out how to compute a text range in the original file id?
   - [x] cleanup some duped code
   - [x] collect macros from `ItemScope.declared_macros()` into symbol index.
        - [x] store declared macros in `ItemScope` so we can figure out where macros were defined for the index.  
   - [x] do something about `SymbolIndex::for_files` - ideally it should use the new module symbol index stuff. 
       - [x] delete `source_file_to_file_symbols` & co...
           - [x] figure out what to do about `library_symbols` 
           - [x] maybe... speed up the new `library_symbols` - the new impl is probably much slower, and definitely much less parallel. **deciding to do nothing here, we can optimize later if necerssary.** 
   - [x] fix failing test: `navigation_target::tests::test_nav_for_symbol` - notably the crate def map doesn't seem to find declarations inside function. 
       - [x] now a bunch of other tests are failing around auto_import & qualify_path handlers. :(
           - [x] need to assoc items in traits and impls
 

Co-authored-by: Jake Heinz <jh@discordapp.com>

crates/base_db/src/fixture.rs

@@ -19,8 +19,8 @@ use crate::{
 pub const WORKSPACE: SourceRootId = SourceRootId(0);
 
 pub trait WithFixture: Default + SourceDatabaseExt + 'static {
-    fn with_single_file(text: &str) -> (Self, FileId) {
-        let fixture = ChangeFixture::parse(text);
+    fn with_single_file(ra_fixture: &str) -> (Self, FileId) {
+        let fixture = ChangeFixture::parse(ra_fixture);
         let mut db = Self::default();
         fixture.change.apply(&mut db);
         assert_eq!(fixture.files.len(), 1);

crates/base_db/src/lib.rs

@@ -102,7 +102,7 @@ fn source_root_crates(db: &dyn SourceDatabaseExt, id: SourceRootId) -> Arc<FxHas
             let root_file = graph[krate].root_file_id;
             db.file_source_root(root_file) == id
         })
-        .collect::<FxHashSet<_>>();
+        .collect();
     Arc::new(res)
 }