Auto merge of #113591 - mdibaiee:genericargs-cleanup, r=oli-obk

refactor(rustc_middle): Substs -> GenericArg

resolves #110793

- [x] rename `SubstsRef` and `InternalSubsts` to `GenericArgsRef<'tcx>` and `GenericArgs<'tcx>`.
- [x] rename variables and fields currently using `substs` to `args`.
- [x] update the module name of `ty::subst` to `ty::generic_args` or sth. Make that module private and publicly reexport its content in the ty module.
- [x] rename `EarlyBinder::subst(_identity)` to `EarlyBinder::instantiate(_identity)`.
- [x] types called `[a-zA-Z]+Substs` renamed to `XArgs`.
- [x] functions containing `substs` now use `args` or `generic_args` (mostly the former).

However, the verb of "substituting" is still being used here and there, mostly in comments. I think that can be a separate PR as part of #110254 to change the verb to `replace_generics` or something similar.

Author: bors

compiler/rustc_borrowck/src/constraint_generation.rs

@@ -7,8 +7,8 @@ use rustc_middle::mir::{
     Body, Local, Location, Place, PlaceRef, ProjectionElem, Rvalue, SourceInfo, Statement,
     StatementKind, Terminator, TerminatorKind, UserTypeProjection,
 };
-use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::visit::TypeVisitable;
+use rustc_middle::ty::GenericArgsRef;
 use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
 
 use crate::{
@@ -49,11 +49,11 @@ struct ConstraintGeneration<'cg, 'tcx> {
 }
 
 impl<'cg, 'tcx> Visitor<'tcx> for ConstraintGeneration<'cg, 'tcx> {
-    /// We sometimes have `substs` within an rvalue, or within a
+    /// We sometimes have `args` within an rvalue, or within a
     /// call. Make them live at the location where they appear.
-    fn visit_substs(&mut self, substs: &SubstsRef<'tcx>, location: Location) {
-        self.add_regular_live_constraint(*substs, location);
-        self.super_substs(substs);
+    fn visit_args(&mut self, args: &GenericArgsRef<'tcx>, location: Location) {
+        self.add_regular_live_constraint(*args, location);
+        self.super_args(args);
     }
 
     /// We sometimes have `region` within an rvalue, or within a

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -702,11 +702,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 .iter()
                 .copied()
                 .find_map(find_fn_kind_from_did),
-            ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => tcx
+            ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => tcx
                 .explicit_item_bounds(def_id)
-                .subst_iter_copied(tcx, substs)
+                .arg_iter_copied(tcx, args)
                 .find_map(|(clause, span)| find_fn_kind_from_did((clause, span))),
-            ty::Closure(_, substs) => match substs.as_closure().kind() {
+            ty::Closure(_, args) => match args.as_closure().kind() {
                 ty::ClosureKind::Fn => Some(hir::Mutability::Not),
                 ty::ClosureKind::FnMut => Some(hir::Mutability::Mut),
                 _ => None,
@@ -1448,11 +1448,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
 
         // Get closure's arguments
-        let ty::Closure(_, substs) = typeck_results.expr_ty(closure_expr).kind() else {
+        let ty::Closure(_, args) = typeck_results.expr_ty(closure_expr).kind() else {
             /* hir::Closure can be a generator too */
             return;
         };
-        let sig = substs.as_closure().sig();
+        let sig = args.as_closure().sig();
         let tupled_params =
             tcx.erase_late_bound_regions(sig.inputs().iter().next().unwrap().map_bound(|&b| b));
         let ty::Tuple(params) = tupled_params.kind() else { return };
@@ -2676,7 +2676,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 kind: TerminatorKind::Call { call_source: CallSource::OverloadedOperator, .. },
                 ..
             }),
-            Some((method_did, method_substs)),
+            Some((method_did, method_args)),
         ) = (
             &self.body[loan.reserve_location.block].terminator,
             rustc_middle::util::find_self_call(
@@ -2689,7 +2689,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             if tcx.is_diagnostic_item(sym::deref_method, method_did) {
                 let deref_target =
                     tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| {
-                        Instance::resolve(tcx, self.param_env, deref_target, method_substs)
+                        Instance::resolve(tcx, self.param_env, deref_target, method_args)
                             .transpose()
                     });
                 if let Some(Ok(instance)) = deref_target {
@@ -2856,11 +2856,11 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             if is_closure {
                 None
             } else {
-                let ty = self.infcx.tcx.type_of(self.mir_def_id()).subst_identity();
+                let ty = self.infcx.tcx.type_of(self.mir_def_id()).instantiate_identity();
                 match ty.kind() {
                     ty::FnDef(_, _) | ty::FnPtr(_) => self.annotate_fn_sig(
                         self.mir_def_id(),
-                        self.infcx.tcx.fn_sig(self.mir_def_id()).subst_identity(),
+                        self.infcx.tcx.fn_sig(self.mir_def_id()).instantiate_identity(),
                     ),
                     _ => None,
                 }
@@ -2902,7 +2902,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         );
                         // Check if our `target` was captured by a closure.
                         if let Rvalue::Aggregate(
-                            box AggregateKind::Closure(def_id, substs),
+                            box AggregateKind::Closure(def_id, args),
                             operands,
                         ) = rvalue
                         {
@@ -2933,7 +2933,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                                 // into a place then we should annotate the closure in
                                 // case it ends up being assigned into the return place.
                                 annotated_closure =
-                                    self.annotate_fn_sig(def_id, substs.as_closure().sig());
+                                    self.annotate_fn_sig(def_id, args.as_closure().sig());
                                 debug!(
                                     "annotate_argument_and_return_for_borrow: \
                                      annotated_closure={:?} assigned_from_local={:?} \

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -168,17 +168,17 @@ impl<'tcx> BorrowExplanation<'tcx> {
                 let local_decl = &body.local_decls[dropped_local];
                 let mut ty = local_decl.ty;
                 if local_decl.source_info.span.desugaring_kind() == Some(DesugaringKind::ForLoop) {
-                    if let ty::Adt(adt, substs) = local_decl.ty.kind() {
+                    if let ty::Adt(adt, args) = local_decl.ty.kind() {
                         if tcx.is_diagnostic_item(sym::Option, adt.did()) {
                             // in for loop desugaring, only look at the `Some(..)` inner type
-                            ty = substs.type_at(0);
+                            ty = args.type_at(0);
                         }
                     }
                 }
                 let (dtor_desc, type_desc) = match ty.kind() {
                     // If type is an ADT that implements Drop, then
                     // simplify output by reporting just the ADT name.
-                    ty::Adt(adt, _substs) if adt.has_dtor(tcx) && !adt.is_box() => {
+                    ty::Adt(adt, _args) if adt.has_dtor(tcx) && !adt.is_box() => {
                         ("`Drop` code", format!("type `{}`", tcx.def_path_str(adt.did())))
                     }
 

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -732,18 +732,18 @@ impl<'tcx> BorrowedContentSource<'tcx> {
 
     fn from_call(func: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Self> {
         match *func.kind() {
-            ty::FnDef(def_id, substs) => {
+            ty::FnDef(def_id, args) => {
                 let trait_id = tcx.trait_of_item(def_id)?;
 
                 let lang_items = tcx.lang_items();
                 if Some(trait_id) == lang_items.deref_trait()
                     || Some(trait_id) == lang_items.deref_mut_trait()
                 {
-                    Some(BorrowedContentSource::OverloadedDeref(substs.type_at(0)))
+                    Some(BorrowedContentSource::OverloadedDeref(args.type_at(0)))
                 } else if Some(trait_id) == lang_items.index_trait()
                     || Some(trait_id) == lang_items.index_mut_trait()
                 {
-                    Some(BorrowedContentSource::OverloadedIndex(substs.type_at(0)))
+                    Some(BorrowedContentSource::OverloadedIndex(args.type_at(0)))
                 } else {
                     None
                 }
@@ -847,7 +847,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             kind: TerminatorKind::Call { fn_span, call_source, .. }, ..
         }) = &self.body[location.block].terminator
         {
-            let Some((method_did, method_substs)) = rustc_middle::util::find_self_call(
+            let Some((method_did, method_args)) = rustc_middle::util::find_self_call(
                 self.infcx.tcx,
                 &self.body,
                 target_temp,
@@ -860,7 +860,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 self.infcx.tcx,
                 self.param_env,
                 method_did,
-                method_substs,
+                method_args,
                 *fn_span,
                 call_source.from_hir_call(),
                 Some(self.infcx.tcx.fn_arg_names(method_did)[0]),
@@ -1039,7 +1039,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         });
                     }
                 }
-                CallKind::Normal { self_arg, desugaring, method_did, method_substs } => {
+                CallKind::Normal { self_arg, desugaring, method_did, method_args } => {
                     let self_arg = self_arg.unwrap();
                     let tcx = self.infcx.tcx;
                     if let Some((CallDesugaringKind::ForLoopIntoIter, _)) = desugaring {
@@ -1106,13 +1106,13 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         // Erase and shadow everything that could be passed to the new infcx.
                         let ty = moved_place.ty(self.body, tcx).ty;
 
-                        if let ty::Adt(def, substs) = ty.kind()
+                        if let ty::Adt(def, args) = ty.kind()
                             && Some(def.did()) == tcx.lang_items().pin_type()
-                            && let ty::Ref(_, _, hir::Mutability::Mut) = substs.type_at(0).kind()
+                            && let ty::Ref(_, _, hir::Mutability::Mut) = args.type_at(0).kind()
                             && let self_ty = self.infcx.instantiate_binder_with_fresh_vars(
                                 fn_call_span,
                                 LateBoundRegionConversionTime::FnCall,
-                                tcx.fn_sig(method_did).subst(tcx, method_substs).input(0),
+                                tcx.fn_sig(method_did).instantiate(tcx, method_args).input(0),
                             )
                             && self.infcx.can_eq(self.param_env, ty, self_ty)
                         {
@@ -1161,7 +1161,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     let parent_self_ty =
                         matches!(tcx.def_kind(parent_did), rustc_hir::def::DefKind::Impl { .. })
                             .then_some(parent_did)
-                            .and_then(|did| match tcx.type_of(did).subst_identity().kind() {
+                            .and_then(|did| match tcx.type_of(did).instantiate_identity().kind() {
                                 ty::Adt(def, ..) => Some(def.did()),
                                 _ => None,
                             });

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -324,10 +324,10 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             ty::Array(..) | ty::Slice(..) => {
                 self.cannot_move_out_of_interior_noncopy(span, ty, None)
             }
-            ty::Closure(def_id, closure_substs)
+            ty::Closure(def_id, closure_args)
                 if def_id.as_local() == Some(self.mir_def_id()) && upvar_field.is_some() =>
             {
-                let closure_kind_ty = closure_substs.as_closure().kind_ty();
+                let closure_kind_ty = closure_args.as_closure().kind_ty();
                 let closure_kind = match closure_kind_ty.to_opt_closure_kind() {
                     Some(kind @ (ty::ClosureKind::Fn | ty::ClosureKind::FnMut)) => kind,
                     Some(ty::ClosureKind::FnOnce) => {

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -22,7 +22,7 @@ use rustc_infer::infer::{
 };
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::{ConstraintCategory, ReturnConstraint};
-use rustc_middle::ty::subst::InternalSubsts;
+use rustc_middle::ty::GenericArgs;
 use rustc_middle::ty::TypeVisitor;
 use rustc_middle::ty::{self, RegionVid, Ty};
 use rustc_middle::ty::{Region, TyCtxt};
@@ -183,9 +183,9 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     fn is_closure_fn_mut(&self, fr: RegionVid) -> bool {
         if let Some(ty::ReFree(free_region)) = self.to_error_region(fr).as_deref()
             && let ty::BoundRegionKind::BrEnv = free_region.bound_region
-            && let DefiningTy::Closure(_, substs) = self.regioncx.universal_regions().defining_ty
+            && let DefiningTy::Closure(_, args) = self.regioncx.universal_regions().defining_ty
         {
-            return substs.as_closure().kind() == ty::ClosureKind::FnMut;
+            return args.as_closure().kind() == ty::ClosureKind::FnMut;
         }
 
         false
@@ -502,12 +502,12 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                                 .to_string(),
                         )
                     }
-                    ty::Adt(adt, substs) => {
-                        let generic_arg = substs[param_index as usize];
-                        let identity_substs =
-                            InternalSubsts::identity_for_item(self.infcx.tcx, adt.did());
-                        let base_ty = Ty::new_adt(self.infcx.tcx, *adt, identity_substs);
-                        let base_generic_arg = identity_substs[param_index as usize];
+                    ty::Adt(adt, args) => {
+                        let generic_arg = args[param_index as usize];
+                        let identity_args =
+                            GenericArgs::identity_for_item(self.infcx.tcx, adt.did());
+                        let base_ty = Ty::new_adt(self.infcx.tcx, *adt, identity_args);
+                        let base_generic_arg = identity_args[param_index as usize];
                         let adt_desc = adt.descr();
 
                         let desc = format!(
@@ -520,12 +520,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                     }
                     ty::FnDef(def_id, _) => {
                         let name = self.infcx.tcx.item_name(*def_id);
-                        let identity_substs =
-                            InternalSubsts::identity_for_item(self.infcx.tcx, *def_id);
+                        let identity_args = GenericArgs::identity_for_item(self.infcx.tcx, *def_id);
                         let desc = format!("a function pointer to `{name}`");
                         let note = format!(
                             "the function `{name}` is invariant over the parameter `{}`",
-                            identity_substs[param_index as usize]
+                            identity_args[param_index as usize]
                         );
                         (desc, note)
                     }
@@ -573,7 +572,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
         let mut output_ty = self.regioncx.universal_regions().unnormalized_output_ty;
         if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = *output_ty.kind() {
-            output_ty = self.infcx.tcx.type_of(def_id).subst_identity()
+            output_ty = self.infcx.tcx.type_of(def_id).instantiate_identity()
         };
 
         debug!("report_fnmut_error: output_ty={:?}", output_ty);
@@ -899,14 +898,14 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         let tcx = self.infcx.tcx;
 
         let instance = if let ConstraintCategory::CallArgument(Some(func_ty)) = category {
-            let (fn_did, substs) = match func_ty.kind() {
-                ty::FnDef(fn_did, substs) => (fn_did, substs),
+            let (fn_did, args) = match func_ty.kind() {
+                ty::FnDef(fn_did, args) => (fn_did, args),
                 _ => return,
             };
-            debug!(?fn_did, ?substs);
+            debug!(?fn_did, ?args);
 
             // Only suggest this on function calls, not closures
-            let ty = tcx.type_of(fn_did).subst_identity();
+            let ty = tcx.type_of(fn_did).instantiate_identity();
             debug!("ty: {:?}, ty.kind: {:?}", ty, ty.kind());
             if let ty::Closure(_, _) = ty.kind() {
                 return;
@@ -916,7 +915,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 tcx,
                 self.param_env,
                 *fn_did,
-                self.infcx.resolve_vars_if_possible(substs),
+                self.infcx.resolve_vars_if_possible(args),
             ) {
                 instance
             } else {