Reduce the amount of passed-around arguments that will get merged into one later anyway

Author: oli-obk

compiler/rustc_middle/src/ty/adjustment.rs

@@ -1,7 +1,5 @@
-use crate::ty::subst::SubstsRef;
 use crate::ty::{self, Ty, TyCtxt};
 use rustc_hir as hir;
-use rustc_hir::def_id::DefId;
 use rustc_hir::lang_items::LangItem;
 use rustc_macros::HashStable;
 use rustc_span::Span;
@@ -121,7 +119,8 @@ pub struct OverloadedDeref<'tcx> {
 }
 
 impl<'tcx> OverloadedDeref<'tcx> {
-    pub fn method_call(&self, tcx: TyCtxt<'tcx>, source: Ty<'tcx>) -> (DefId, SubstsRef<'tcx>) {
+    /// Get the zst function item type for this method call.
+    pub fn method_call(&self, tcx: TyCtxt<'tcx>, source: Ty<'tcx>) -> Ty<'tcx> {
         let trait_def_id = match self.mutbl {
             hir::Mutability::Not => tcx.require_lang_item(LangItem::Deref, None),
             hir::Mutability::Mut => tcx.require_lang_item(LangItem::DerefMut, None),
@@ -132,7 +131,7 @@ impl<'tcx> OverloadedDeref<'tcx> {
             .find(|m| m.kind == ty::AssocKind::Fn)
             .unwrap()
             .def_id;
-        (method_def_id, tcx.mk_substs_trait(source, &[]))
+        tcx.mk_fn_def(method_def_id, tcx.mk_substs_trait(source, &[]))
     }
 }
 

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -14,11 +14,10 @@ use rustc_middle::thir::*;
 use rustc_middle::ty::adjustment::{
     Adjust, Adjustment, AutoBorrow, AutoBorrowMutability, PointerCast,
 };
-use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
+use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{
     self, AdtKind, InlineConstSubsts, InlineConstSubstsParts, ScalarInt, Ty, UpvarSubsts, UserType,
 };
-use rustc_span::def_id::DefId;
 use rustc_span::Span;
 use rustc_target::abi::VariantIdx;
 
@@ -806,23 +805,25 @@ impl<'tcx> Cx<'tcx> {
         &mut self,
         expr: &hir::Expr<'_>,
         span: Span,
-        overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
+        overloaded_callee: Option<Ty<'tcx>>,
     ) -> Expr<'tcx> {
         let temp_lifetime =
             self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id);
-        let (def_id, substs, user_ty) = match overloaded_callee {
-            Some((def_id, substs)) => (def_id, substs, None),
+        let (ty, user_ty) = match overloaded_callee {
+            Some(fn_def) => (fn_def, None),
             None => {
                 let (kind, def_id) =
                     self.typeck_results().type_dependent_def(expr.hir_id).unwrap_or_else(|| {
                         span_bug!(expr.span, "no type-dependent def for method callee")
                     });
                 let user_ty = self.user_substs_applied_to_res(expr.hir_id, Res::Def(kind, def_id));
                 debug!("method_callee: user_ty={:?}", user_ty);
-                (def_id, self.typeck_results().node_substs(expr.hir_id), user_ty)
+                (
+                    self.tcx().mk_fn_def(def_id, self.typeck_results().node_substs(expr.hir_id)),
+                    user_ty,
+                )
             }
         };
-        let ty = self.tcx().mk_fn_def(def_id, substs);
         Expr { temp_lifetime, ty, span, kind: ExprKind::ZstLiteral { user_ty } }
     }
 
@@ -957,7 +958,7 @@ impl<'tcx> Cx<'tcx> {
         &mut self,
         expr: &'tcx hir::Expr<'tcx>,
         place_ty: Ty<'tcx>,
-        overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
+        overloaded_callee: Option<Ty<'tcx>>,
         args: Box<[ExprId]>,
         span: Span,
     ) -> ExprKind<'tcx> {