Remove all upcasts!

It turns out there were a lot redundant too.

crates/ide/src/expand_macro.rs

@@ -234,6 +234,8 @@ fn _format(
     file_id: FileId,
     expansion: &str,
 ) -> Option<String> {
+    use ide_db::base_db::RootQueryDb;
+
     // hack until we get hygiene working (same character amount to preserve formatting as much as possible)
     const DOLLAR_CRATE_REPLACE: &str = "__r_a_";
     const BUILTIN_REPLACE: &str = "builtin__POUND";
@@ -247,9 +249,8 @@ fn _format(
     };
     let expansion = format!("{prefix}{expansion}{suffix}");
 
-    let upcast_db = ide_db::base_db::Upcast::<dyn ide_db::base_db::RootQueryDb>::upcast(db);
-    let &crate_id = upcast_db.relevant_crates(file_id).iter().next()?;
-    let edition = crate_id.data(upcast_db).edition;
+    let &crate_id = db.relevant_crates(file_id).iter().next()?;
+    let edition = crate_id.data(db).edition;
 
     #[allow(clippy::disallowed_methods)]
     let mut cmd = std::process::Command::new(toolchain::Tool::Rustfmt.path());

crates/ide/src/goto_definition.rs

@@ -11,7 +11,7 @@ use hir::{
 };
 use ide_db::{
     RootDatabase, SymbolKind,
-    base_db::{AnchoredPath, RootQueryDb, SourceDatabase, Upcast},
+    base_db::{AnchoredPath, SourceDatabase},
     defs::{Definition, IdentClass},
     famous_defs::FamousDefs,
     helpers::pick_best_token,
@@ -222,8 +222,7 @@ fn try_lookup_include_path(
     }
     let path = token.value.value().ok()?;
 
-    let file_id = Upcast::<dyn RootQueryDb>::upcast(sema.db)
-        .resolve_path(AnchoredPath { anchor: file_id, path: &path })?;
+    let file_id = sema.db.resolve_path(AnchoredPath { anchor: file_id, path: &path })?;
     let size = sema.db.file_text(file_id).text(sema.db).len().try_into().ok()?;
     Some(NavigationTarget {
         file_id,

crates/ide/src/goto_type_definition.rs

@@ -1,5 +1,5 @@
 use hir::GenericParam;
-use ide_db::{RootDatabase, base_db::Upcast, defs::Definition, helpers::pick_best_token};
+use ide_db::{RootDatabase, defs::Definition, helpers::pick_best_token};
 use syntax::{AstNode, SyntaxKind::*, SyntaxToken, T, ast, match_ast};
 
 use crate::{FilePosition, NavigationTarget, RangeInfo, TryToNav};
@@ -87,7 +87,7 @@ pub(crate) fn goto_type_definition(
                             ast::Pat(it) => sema.type_of_pat(&it)?.original,
                             ast::SelfParam(it) => sema.type_of_self(&it)?,
                             ast::Type(it) => sema.resolve_type(&it)?,
-                            ast::RecordField(it) => sema.to_def(&it)?.ty(db.upcast()),
+                            ast::RecordField(it) => sema.to_def(&it)?.ty(db),
                             // can't match on RecordExprField directly as `ast::Expr` will match an iteration too early otherwise
                             ast::NameRef(it) => {
                                 if let Some(record_field) = ast::RecordExprField::for_name_ref(&it) {

crates/ide/src/lib.rs

@@ -66,8 +66,7 @@ use hir::{ChangeWithProcMacros, sym};
 use ide_db::{
     FxHashMap, FxIndexSet, LineIndexDatabase,
     base_db::{
-        CrateOrigin, CrateWorkspaceData, Env, FileSet, RootQueryDb, SourceDatabase, Upcast,
-        VfsPath,
+        CrateOrigin, CrateWorkspaceData, Env, FileSet, RootQueryDb, SourceDatabase, VfsPath,
         salsa::{AsDynDatabase, Cancelled},
     },
     prime_caches, symbol_index,
@@ -623,10 +622,7 @@ impl Analysis {
 
     /// Returns crates that this file *might* belong to.
     pub fn relevant_crates_for(&self, file_id: FileId) -> Cancellable<Vec<Crate>> {
-        self.with_db(|db| {
-            let db = Upcast::<dyn RootQueryDb>::upcast(db);
-            db.relevant_crates(file_id).iter().copied().collect()
-        })
+        self.with_db(|db| db.relevant_crates(file_id).iter().copied().collect())
     }
 
     /// Returns the edition of the given crate.

crates/ide/src/parent_module.rs

@@ -1,7 +1,7 @@
 use hir::{Semantics, db::DefDatabase};
 use ide_db::{
     FileId, FilePosition, RootDatabase,
-    base_db::{Crate, RootQueryDb, Upcast},
+    base_db::{Crate, RootQueryDb},
 };
 use itertools::Itertools;
 use syntax::{
@@ -54,9 +54,7 @@ pub(crate) fn parent_module(db: &RootDatabase, position: FilePosition) -> Vec<Na
 
 /// This returns `Vec` because a module may be included from several places.
 pub(crate) fn crates_for(db: &RootDatabase, file_id: FileId) -> Vec<Crate> {
-    let root_db = Upcast::<dyn RootQueryDb>::upcast(db);
-    root_db
-        .relevant_crates(file_id)
+    db.relevant_crates(file_id)
         .iter()
         .copied()
         .filter(|&crate_id| db.crate_def_map(crate_id).modules_for_file(file_id).next().is_some())