Rollup merge of #59216 - stepnivlk:type_dependent_defs-wrappers, r=oli-obk

Type dependent defs wrappers

First of all, forgive me if something would seem lame to you or I offend some rule (although I tried to read through docs), this is my first PR.

Issue: https://github.com/rust-lang/rust/issues/59094

This PR adds 3 helper methods to `TypeckTables`:
* `opt_type_dependent_def`
* `opt_type_dependent_def_id`
* `type_dependent_def_id`

I didn't add `type_dependent_def` as was proposed in the issue simply because it wasn't used anywhere in the code. Only non-option wrapped`type_dependent_defs()[]` accesses were found in clippy which always called `def_id()` on result.
Speaking of clippy, should I open separate PR in its own repo, given it's used as submodule here?

Sry it took me so long, as I said I'm new here and I had tough week :).

10 files changed, 24 insertions, 19 deletions

diff --git a/src/librustc/middle/dead.rs b/src/librustc/middle/dead.rs
index 0a0a1dee7f0..8e8543dd334 100644
--- a/src/librustc/middle/dead.rs
+++ b/src/librustc/middle/dead.rs
@@ -98,8 +98,8 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
     }
 
     fn lookup_and_handle_method(&mut self, id: hir::HirId) {
-        if let Some(def) = self.tables.type_dependent_defs().get(id) {
-            self.check_def_id(def.def_id());
+        if let Some(def_id) = self.tables.type_dependent_def_id(id) {
+            self.check_def_id(def_id);
         } else {
             bug!("no type-dependent def for method");
         }
diff --git a/src/librustc/middle/expr_use_visitor.rs b/src/librustc/middle/expr_use_visitor.rs
index 6c8d9fe29d7..01e57273e54 100644
--- a/src/librustc/middle/expr_use_visitor.rs
+++ b/src/librustc/middle/expr_use_visitor.rs
@@ -559,8 +559,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
             }
             ty::Error => { }
             _ => {
-                if let Some(def) = self.mc.tables.type_dependent_defs().get(call.hir_id) {
-                    let def_id = def.def_id();
+                if let Some(def_id) = self.mc.tables.type_dependent_def_id(call.hir_id) {
                     let call_scope = region::Scope {
                         id: call.hir_id.local_id,
                         data: region::ScopeData::Node
diff --git a/src/librustc/middle/reachable.rs b/src/librustc/middle/reachable.rs
index b57f96f2d46..b55e840596b 100644
--- a/src/librustc/middle/reachable.rs
+++ b/src/librustc/middle/reachable.rs
@@ -97,7 +97,7 @@ impl<'a, 'tcx> Visitor<'tcx> for ReachableContext<'a, 'tcx> {
                 Some(self.tables.qpath_def(qpath, expr.hir_id))
             }
             hir::ExprKind::MethodCall(..) => {
-                self.tables.type_dependent_defs().get(expr.hir_id).cloned()
+                self.tables.type_dependent_def(expr.hir_id)
             }
             _ => None
         };
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 6de0a39c91b..ea003ba1ac7 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -482,6 +482,15 @@ impl<'tcx> TypeckTables<'tcx> {
         }
     }
 
+    pub fn type_dependent_def(&self, id: HirId) -> Option<Def> {
+        validate_hir_id_for_typeck_tables(self.local_id_root, id, false);
+        self.type_dependent_defs.get(&id.local_id).cloned()
+    }
+
+    pub fn type_dependent_def_id(&self, id: HirId) -> Option<DefId> {
+        self.type_dependent_def(id).map(|def| def.def_id())
+    }
+
     pub fn type_dependent_defs_mut(&mut self) -> LocalTableInContextMut<'_, Def> {
         LocalTableInContextMut {
             local_id_root: self.local_id_root,
diff --git a/src/librustc_lint/unused.rs b/src/librustc_lint/unused.rs
index ebbd2779841..37c147d93d8 100644
--- a/src/librustc_lint/unused.rs
+++ b/src/librustc_lint/unused.rs
@@ -112,7 +112,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
                 }
             },
             hir::ExprKind::MethodCall(..) => {
-                cx.tables.type_dependent_defs().get(expr.hir_id).cloned()
+                cx.tables.type_dependent_def(expr.hir_id)
             },
             _ => None
         };
diff --git a/src/librustc_mir/hair/cx/expr.rs b/src/librustc_mir/hair/cx/expr.rs
index 2ca44ecaba2..e4f92f81e9f 100644
--- a/src/librustc_mir/hair/cx/expr.rs
+++ b/src/librustc_mir/hair/cx/expr.rs
@@ -834,13 +834,11 @@ fn method_callee<'a, 'gcx, 'tcx>(
     let (def_id, substs, user_ty) = match overloaded_callee {
         Some((def_id, substs)) => (def_id, substs, None),
         None => {
-            let type_dependent_defs = cx.tables().type_dependent_defs();
-            let def = type_dependent_defs
-                .get(expr.hir_id)
+            let def = cx.tables().type_dependent_def(expr.hir_id)
                 .unwrap_or_else(|| {
                     span_bug!(expr.span, "no type-dependent def for method callee")
                 });
-            let user_ty = user_substs_applied_to_def(cx, expr.hir_id, def);
+            let user_ty = user_substs_applied_to_def(cx, expr.hir_id, &def);
             debug!("method_callee: user_ty={:?}", user_ty);
             (def.def_id(), cx.tables().node_substs(expr.hir_id), user_ty)
         }
diff --git a/src/librustc_passes/rvalue_promotion.rs b/src/librustc_passes/rvalue_promotion.rs
index 71eb6ed7e05..a0a0d7be1b9 100644
--- a/src/librustc_passes/rvalue_promotion.rs
+++ b/src/librustc_passes/rvalue_promotion.rs
@@ -405,8 +405,7 @@ fn check_expr_kind<'a, 'tcx>(
             for index in hirvec.iter() {
                 method_call_result &= v.check_expr(index);
             }
-            if let Some(def) = v.tables.type_dependent_defs().get(e.hir_id) {
-                let def_id = def.def_id();
+            if let Some(def_id) = v.tables.type_dependent_def_id(e.hir_id) {
                 match v.tcx.associated_item(def_id).container {
                     ty::ImplContainer(_) => method_call_result & v.handle_const_fn_call(def_id),
                     ty::TraitContainer(_) => NotPromotable,
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index f155beaaff2..adb1a4b1308 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -1053,8 +1053,8 @@ impl<'a, 'tcx> Visitor<'tcx> for TypePrivacyVisitor<'a, 'tcx> {
             hir::ExprKind::MethodCall(_, span, _) => {
                 // Method calls have to be checked specially.
                 self.span = span;
-                if let Some(def) = self.tables.type_dependent_defs().get(expr.hir_id) {
-                    if self.visit(self.tcx.type_of(def.def_id())) {
+                if let Some(def_id) = self.tables.type_dependent_def_id(expr.hir_id) {
+                    if self.visit(self.tcx.type_of(def_id)) {
                         return;
                     }
                 } else {
@@ -1083,7 +1083,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypePrivacyVisitor<'a, 'tcx> {
                 _ => None,
             }
             hir::QPath::TypeRelative(..) => {
-                self.tables.type_dependent_defs().get(id).cloned()
+                self.tables.type_dependent_def(id)
             }
         };
         if let Some(def) = def {
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index 828ef802dd7..898ea62046d 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -573,8 +573,8 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
             }
             ast::ExprKind::MethodCall(ref seg, ..) => {
                 let expr_hir_id = self.tcx.hir().definitions().node_to_hir_id(expr.id);
-                let method_id = match self.tables.type_dependent_defs().get(expr_hir_id) {
-                    Some(id) => id.def_id(),
+                let method_id = match self.tables.type_dependent_def_id(expr_hir_id) {
+                    Some(id) => id,
                     None => {
                         debug!("Could not resolve method id for {:?}", expr);
                         return None;
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 3d904d518ca..5c498923379 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4802,10 +4802,10 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 (self.to_ty(qself), qself, segment)
             }
         };
-        if let Some(cached_def) = self.tables.borrow().type_dependent_defs().get(hir_id) {
+        if let Some(cached_def) = self.tables.borrow().type_dependent_def(hir_id) {
             // Return directly on cache hit. This is useful to avoid doubly reporting
             // errors with default match binding modes. See #44614.
-            return (*cached_def, Some(ty), slice::from_ref(&**item_segment))
+            return (cached_def, Some(ty), slice::from_ref(&**item_segment))
         }
         let item_name = item_segment.ident;
         let def = match self.resolve_ufcs(span, item_name, ty, hir_id) {