internal: reduce body lookups in expr diagnostics

rosefromthedead · rosefromthedead · commit d2d653c438e9 · 2024-01-14T15:39:07.000Z
diff --git a/crates/hir-ty/src/diagnostics/expr.rs b/crates/hir-ty/src/diagnostics/expr.rs
@@ -50,26 +50,25 @@ impl BodyValidationDiagnostic {
     pub fn collect(db: &dyn HirDatabase, owner: DefWithBodyId) -> Vec<BodyValidationDiagnostic> {
         let _p = profile::span("BodyValidationDiagnostic::collect");
         let infer = db.infer(owner);
-        let mut validator = ExprValidator::new(owner, infer);
+        let body = db.body(owner);
+        let mut validator = ExprValidator { owner, body, infer, diagnostics: Vec::new() };
         validator.validate_body(db);
         validator.diagnostics
     }
 }
 
 struct ExprValidator {
     owner: DefWithBodyId,
+    body: Arc<Body>,
     infer: Arc<InferenceResult>,
     pub(super) diagnostics: Vec<BodyValidationDiagnostic>,
 }
 
 impl ExprValidator {
-    fn new(owner: DefWithBodyId, infer: Arc<InferenceResult>) -> ExprValidator {
-        ExprValidator { owner, infer, diagnostics: Vec::new() }
-    }
-
     fn validate_body(&mut self, db: &dyn HirDatabase) {
-        let body = db.body(self.owner);
         let mut filter_map_next_checker = None;
+        // we'll pass &mut self while iterating over body.exprs, so they need to be disjoint
+        let body = Arc::clone(&self.body);
 
         for (id, expr) in body.exprs.iter() {
             if let Some((variant, missed_fields, true)) =
@@ -152,8 +151,6 @@ impl ExprValidator {
         arms: &[MatchArm],
         db: &dyn HirDatabase,
     ) {
-        let body = db.body(self.owner);
-
         let scrut_ty = &self.infer[scrutinee_expr];
         if scrut_ty.is_unknown() {
             return;
@@ -181,13 +178,13 @@ impl ExprValidator {
                         .as_reference()
                         .map(|(match_expr_ty, ..)| match_expr_ty == pat_ty)
                         .unwrap_or(false))
-                    && types_of_subpatterns_do_match(arm.pat, &body, &self.infer)
+                    && types_of_subpatterns_do_match(arm.pat, &self.body, &self.infer)
                 {
                     // If we had a NotUsefulMatchArm diagnostic, we could
                     // check the usefulness of each pattern as we added it
                     // to the matrix here.
                     let m_arm = match_check::MatchArm {
-                        pat: self.lower_pattern(&cx, arm.pat, db, &body, &mut has_lowering_errors),
+                        pat: self.lower_pattern(&cx, arm.pat, db, &mut has_lowering_errors),
                         has_guard: arm.guard.is_some(),
                     };
                     m_arms.push(m_arm);
@@ -224,10 +221,9 @@ impl ExprValidator {
         cx: &MatchCheckCtx<'_, 'p>,
         pat: PatId,
         db: &dyn HirDatabase,
-        body: &Body,
         have_errors: &mut bool,
     ) -> &'p DeconstructedPat<'p> {
-        let mut patcx = match_check::PatCtxt::new(db, &self.infer, body);
+        let mut patcx = match_check::PatCtxt::new(db, &self.infer, &self.body);
         let pattern = patcx.lower_pattern(pat);
         let pattern = cx.pattern_arena.alloc(DeconstructedPat::from_pat(cx, &pattern));
         if !patcx.errors.is_empty() {
