Rollup merge of rust-lang#120958 - ShoyuVanilla:remove-subst, r=oli-obk

Dejargonize `subst`

In favor of rust-lang#110793, replace almost every occurence of `subst` and `substitution` from rustc codes, but they still remains in subtrees under `src/tools/` like clippy and test codes (I'd like to replace them after this)

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -691,7 +691,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
 
         // If the type is opaque/param/closure, and it is Fn or FnMut, let's suggest (mutably)
         // borrowing the type, since `&mut F: FnMut` iff `F: FnMut` and similarly for `Fn`.
-        // These types seem reasonably opaque enough that they could be substituted with their
+        // These types seem reasonably opaque enough that they could be instantiated with their
         // borrowed variants in a function body when we see a move error.
         let borrow_level = match *ty.kind() {
             ty::Param(_) => tcx

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -45,7 +45,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// be allowed:
     /// `fn f<'a: 'b, 'b: 'a>(x: *mut &'b i32) -> impl Sized + 'a { x }`
     ///
-    /// Then we map the regions in both the type and the subst to their
+    /// Then we map the regions in both the type and the generic parameters to their
     /// `external_name` giving `concrete_type = &'a i32`,
     /// `args = ['static, 'a]`. This will then allow
     /// `infer_opaque_definition_from_instantiation` to determine that
@@ -77,9 +77,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             let args = opaque_type_key.args;
             debug!(?concrete_type, ?args);
 
-            let mut subst_regions = vec![self.universal_regions.fr_static];
+            let mut arg_regions = vec![self.universal_regions.fr_static];
 
-            let to_universal_region = |vid, subst_regions: &mut Vec<_>| {
+            let to_universal_region = |vid, arg_regions: &mut Vec<_>| {
                 trace!(?vid);
                 let scc = self.constraint_sccs.scc(vid);
                 trace!(?scc);
@@ -88,11 +88,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 }) {
                     Some(region) => {
                         let vid = self.universal_regions.to_region_vid(region);
-                        subst_regions.push(vid);
+                        arg_regions.push(vid);
                         region
                     }
                     None => {
-                        subst_regions.push(vid);
+                        arg_regions.push(vid);
                         ty::Region::new_error_with_message(
                             infcx.tcx,
                             concrete_type.span,
@@ -106,10 +106,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             // This will ensure they get precedence when folding the regions in the concrete type.
             if let Some(&ci) = member_constraints.get(&opaque_type_key) {
                 for &vid in self.member_constraints.choice_regions(ci) {
-                    to_universal_region(vid, &mut subst_regions);
+                    to_universal_region(vid, &mut arg_regions);
                 }
             }
-            debug!(?subst_regions);
+            debug!(?arg_regions);
 
             // Next, insert universal regions from args, so we can translate regions that appear
             // in them but are not subject to member constraints, for instance closure args.
@@ -119,18 +119,18 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     return region;
                 }
                 let vid = self.to_region_vid(region);
-                to_universal_region(vid, &mut subst_regions)
+                to_universal_region(vid, &mut arg_regions)
             });
             debug!(?universal_args);
-            debug!(?subst_regions);
+            debug!(?arg_regions);
 
             // Deduplicate the set of regions while keeping the chosen order.
-            let subst_regions = subst_regions.into_iter().collect::<FxIndexSet<_>>();
-            debug!(?subst_regions);
+            let arg_regions = arg_regions.into_iter().collect::<FxIndexSet<_>>();
+            debug!(?arg_regions);
 
             let universal_concrete_type =
                 infcx.tcx.fold_regions(concrete_type, |region, _| match *region {
-                    ty::ReVar(vid) => subst_regions
+                    ty::ReVar(vid) => arg_regions
                         .iter()
                         .find(|ur_vid| self.eval_equal(vid, **ur_vid))
                         .and_then(|ur_vid| self.definitions[*ur_vid].external_name)

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -554,18 +554,20 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
     /// Call this on things you got out of the MIR (so it is as generic as the current
     /// stack frame), to bring it into the proper environment for this interpreter.
-    pub(super) fn subst_from_current_frame_and_normalize_erasing_regions<
+    pub(super) fn instantiate_from_current_frame_and_normalize_erasing_regions<
         T: TypeFoldable<TyCtxt<'tcx>>,
     >(
         &self,
         value: T,
     ) -> Result<T, ErrorHandled> {
-        self.subst_from_frame_and_normalize_erasing_regions(self.frame(), value)
+        self.instantiate_from_frame_and_normalize_erasing_regions(self.frame(), value)
     }
 
     /// Call this on things you got out of the MIR (so it is as generic as the provided
     /// stack frame), to bring it into the proper environment for this interpreter.
-    pub(super) fn subst_from_frame_and_normalize_erasing_regions<T: TypeFoldable<TyCtxt<'tcx>>>(
+    pub(super) fn instantiate_from_frame_and_normalize_erasing_regions<
+        T: TypeFoldable<TyCtxt<'tcx>>,
+    >(
         &self,
         frame: &Frame<'mir, 'tcx, M::Provenance, M::FrameExtra>,
         value: T,
@@ -656,7 +658,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
         let layout = from_known_layout(self.tcx, self.param_env, layout, || {
             let local_ty = frame.body.local_decls[local].ty;
-            let local_ty = self.subst_from_frame_and_normalize_erasing_regions(frame, local_ty)?;
+            let local_ty =
+                self.instantiate_from_frame_and_normalize_erasing_regions(frame, local_ty)?;
             self.layout_of(local_ty)
         })?;
 
@@ -791,8 +794,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
         if M::POST_MONO_CHECKS {
             for &const_ in &body.required_consts {
-                let c =
-                    self.subst_from_current_frame_and_normalize_erasing_regions(const_.const_)?;
+                let c = self
+                    .instantiate_from_current_frame_and_normalize_erasing_regions(const_.const_)?;
                 c.eval(*self.tcx, self.param_env, Some(const_.span)).map_err(|err| {
                     err.emit_note(*self.tcx);
                     err

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -696,9 +696,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         trace!("eval_place_to_op: got {:?}", op);
         // Sanity-check the type we ended up with.
         if cfg!(debug_assertions) {
-            let normalized_place_ty = self.subst_from_current_frame_and_normalize_erasing_regions(
-                mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty,
-            )?;
+            let normalized_place_ty = self
+                .instantiate_from_current_frame_and_normalize_erasing_regions(
+                    mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty,
+                )?;
             if !mir_assign_valid_types(
                 *self.tcx,
                 self.param_env,
@@ -731,8 +732,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             &Copy(place) | &Move(place) => self.eval_place_to_op(place, layout)?,
 
             Constant(constant) => {
-                let c =
-                    self.subst_from_current_frame_and_normalize_erasing_regions(constant.const_)?;
+                let c = self.instantiate_from_current_frame_and_normalize_erasing_regions(
+                    constant.const_,
+                )?;
 
                 // This can still fail:
                 // * During ConstProp, with `TooGeneric` or since the `required_consts` were not all

compiler/rustc_const_eval/src/interpret/place.rs

@@ -542,9 +542,10 @@ where
         trace!("{:?}", self.dump_place(&place));
         // Sanity-check the type we ended up with.
         if cfg!(debug_assertions) {
-            let normalized_place_ty = self.subst_from_current_frame_and_normalize_erasing_regions(
-                mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty,
-            )?;
+            let normalized_place_ty = self
+                .instantiate_from_current_frame_and_normalize_erasing_regions(
+                    mir_place.ty(&self.frame().body.local_decls, *self.tcx).ty,
+                )?;
             if !mir_assign_valid_types(
                 *self.tcx,
                 self.param_env,

compiler/rustc_const_eval/src/interpret/step.rs

@@ -235,7 +235,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             NullaryOp(ref null_op, ty) => {
-                let ty = self.subst_from_current_frame_and_normalize_erasing_regions(ty)?;
+                let ty = self.instantiate_from_current_frame_and_normalize_erasing_regions(ty)?;
                 let layout = self.layout_of(ty)?;
                 if let mir::NullOp::SizeOf | mir::NullOp::AlignOf = null_op
                     && layout.is_unsized()
@@ -276,7 +276,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Cast(cast_kind, ref operand, cast_ty) => {
                 let src = self.eval_operand(operand, None)?;
                 let cast_ty =
-                    self.subst_from_current_frame_and_normalize_erasing_regions(cast_ty)?;
+                    self.instantiate_from_current_frame_and_normalize_erasing_regions(cast_ty)?;
                 self.cast(&src, cast_kind, cast_ty, &dest)?;
             }
 

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -173,7 +173,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Drop { place, target, unwind, replace: _ } => {
                 let frame = self.frame();
                 let ty = place.ty(&frame.body.local_decls, *self.tcx).ty;
-                let ty = self.subst_from_frame_and_normalize_erasing_regions(frame, ty)?;
+                let ty = self.instantiate_from_frame_and_normalize_erasing_regions(frame, ty)?;
                 let instance = Instance::resolve_drop_in_place(*self.tcx, ty);
                 if let ty::InstanceDef::DropGlue(_, None) = instance.def {
                     // This is the branch we enter if and only if the dropped type has no drop glue
@@ -672,8 +672,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                         // Construct the destination place for this argument. At this point all
                         // locals are still dead, so we cannot construct a `PlaceTy`.
                         let dest = mir::Place::from(local);
-                        // `layout_of_local` does more than just the substitution we need to get the
-                        // type, but the result gets cached so this avoids calling the substitution
+                        // `layout_of_local` does more than just the instantiation we need to get the
+                        // type, but the result gets cached so this avoids calling the instantiation
                         // query *again* the next time this local is accessed.
                         let ty = self.layout_of_local(self.frame(), local, None)?.ty;
                         if Some(local) == body.spread_arg {

compiler/rustc_const_eval/src/interpret/util.rs

@@ -19,11 +19,11 @@ where
     }
 
     struct FoundParam;
-    struct UsedParamsNeedSubstVisitor<'tcx> {
+    struct UsedParamsNeedInstantiationVisitor<'tcx> {
         tcx: TyCtxt<'tcx>,
     }
 
-    impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for UsedParamsNeedSubstVisitor<'tcx> {
+    impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for UsedParamsNeedInstantiationVisitor<'tcx> {
         type BreakTy = FoundParam;
 
         fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
@@ -39,17 +39,17 @@ where
                 | ty::FnDef(def_id, args) => {
                     let instance = ty::InstanceDef::Item(def_id);
                     let unused_params = self.tcx.unused_generic_params(instance);
-                    for (index, subst) in args.into_iter().enumerate() {
+                    for (index, arg) in args.into_iter().enumerate() {
                         let index = index
                             .try_into()
                             .expect("more generic parameters than can fit into a `u32`");
                         // Only recurse when generic parameters in fns, closures and coroutines
                         // are used and have to be instantiated.
                         //
-                        // Just in case there are closures or coroutines within this subst,
+                        // Just in case there are closures or coroutines within this arg,
                         // recurse.
-                        if unused_params.is_used(index) && subst.has_param() {
-                            return subst.visit_with(self);
+                        if unused_params.is_used(index) && arg.has_param() {
+                            return arg.visit_with(self);
                         }
                     }
                     ControlFlow::Continue(())
@@ -66,7 +66,7 @@ where
         }
     }
 
-    let mut vis = UsedParamsNeedSubstVisitor { tcx };
+    let mut vis = UsedParamsNeedInstantiationVisitor { tcx };
     if matches!(ty.visit_with(&mut vis), ControlFlow::Break(FoundParam)) {
         throw_inval!(TooGeneric);
     } else {

compiler/rustc_error_codes/src/error_codes/E0139.md

@@ -22,17 +22,17 @@ fn foo<T>(x: Vec<T>) {
 In this specific case there's a good chance that the transmute is harmless (but
 this is not guaranteed by Rust). However, when alignment and enum optimizations
 come into the picture, it's quite likely that the sizes may or may not match
-with different type parameter substitutions. It's not possible to check this for
-_all_ possible types, so `transmute()` simply only accepts types without any
-unsubstituted type parameters.
+with different type parameter instantiations. It's not possible to check this
+for _all_ possible types, so `transmute()` simply only accepts types without any
+uninstantiated type parameters.
 
 If you need this, there's a good chance you're doing something wrong. Keep in
 mind that Rust doesn't guarantee much about the layout of different structs
 (even two structs with identical declarations may have different layouts). If
 there is a solution that avoids the transmute entirely, try it instead.
 
 If it's possible, hand-monomorphize the code by writing the function for each
-possible type substitution. It's possible to use traits to do this cleanly,
+possible type instantiation. It's possible to use traits to do this cleanly,
 for example:
 
 ```

compiler/rustc_error_codes/src/error_codes/E0230.md

@@ -15,9 +15,9 @@ There will be an error about `bool` not implementing `Index<u8>`, followed by a
 note saying "the type `bool` cannot be indexed by `u8`".
 
 As you can see, you can specify type parameters in curly braces for
-substitution with the actual types (using the regular format string syntax) in
-a given situation. Furthermore, `{Self}` will substitute to the type (in this
-case, `bool`) that we tried to use.
+instantiation with the actual types (using the regular format string syntax) in
+a given situation. Furthermore, `{Self}` will be instantiated to the type (in
+this case, `bool`) that we tried to use.
 
 This error appears when the curly braces contain an identifier which doesn't
 match with any of the type parameters or the string `Self`. This might happen

compiler/rustc_error_codes/src/error_codes/E0231.md

@@ -15,9 +15,9 @@ there will be an error about `bool` not implementing `Index<u8>`, followed by a
 note saying "the type `bool` cannot be indexed by `u8`".
 
 As you can see, you can specify type parameters in curly braces for
-substitution with the actual types (using the regular format string syntax) in
-a given situation. Furthermore, `{Self}` will substitute to the type (in this
-case, `bool`) that we tried to use.
+instantiation with the actual types (using the regular format string syntax) in
+a given situation. Furthermore, `{Self}` will be instantiated to the type (in
+this case, `bool`) that we tried to use.
 
 This error appears when the curly braces do not contain an identifier. Please
 add one of the same name as a type parameter. If you intended to use literal

compiler/rustc_error_codes/src/error_codes/E0393.md

@@ -12,12 +12,12 @@ fn together_we_will_rule_the_galaxy(son: &A) {}
 ```
 
 A trait object is defined over a single, fully-defined trait. With a regular
-default parameter, this parameter can just be substituted in. However, if the
+default parameter, this parameter can just be instantiated in. However, if the
 default parameter is `Self`, the trait changes for each concrete type; i.e.
 `i32` will be expected to implement `A<i32>`, `bool` will be expected to
 implement `A<bool>`, etc... These types will not share an implementation of a
 fully-defined trait; instead they share implementations of a trait with
-different parameters substituted in for each implementation. This is
+different parameters instantiated in for each implementation. This is
 irreconcilable with what we need to make a trait object work, and is thus
 disallowed. Making the trait concrete by explicitly specifying the value of the
 defaulted parameter will fix this issue. Fixed example:

compiler/rustc_error_codes/src/error_codes/E0794.md

@@ -14,7 +14,7 @@ let _ = foo::<'static>;
 
 The type of a concrete instance of a generic function is universally quantified
 over late-bound lifetime parameters. This is because we want the function to
-work for any lifetime substituted for the late-bound lifetime parameter, no
+work for any lifetime instantiated for the late-bound lifetime parameter, no
 matter where the function is called. Consequently, it doesn't make sense to
 specify arguments for late-bound lifetime parameters, since they are not
 resolved until the function's call site(s).
@@ -56,7 +56,7 @@ let bar_fn3 = bar::<Bar>; // OK
 
 In the definition of `bar`, the lifetime parameter `'a` is late-bound, while
 `'b` is early-bound. This is reflected in the type annotation for `bar_fn`,
-where `'a` is universally quantified and `'b` is substituted by a specific
+where `'a` is universally quantified and `'b` is instantiated with a specific
 lifetime. It is not allowed to explicitly specify early-bound lifetime
 arguments when late-bound lifetime parameters are present (as for `bar_fn2`,
 see [issue #42868](https://github.com/rust-lang/rust/issues/42868)), although

compiler/rustc_hir/src/hir.rs

@@ -2536,7 +2536,7 @@ pub struct OpaqueTy<'hir> {
     /// lifetimes that are captured from the function signature they originate from.
     ///
     /// This is done by generating a new early-bound lifetime parameter local to the
-    /// opaque which is substituted in the function signature with the late-bound
+    /// opaque which is instantiated in the function signature with the late-bound
     /// lifetime.
     ///
     /// This mapping associated a captured lifetime (first parameter) with the new

compiler/rustc_hir_analysis/messages.ftl

@@ -153,6 +153,8 @@ hir_analysis_function_not_have_default_implementation = function doesn't have a
 hir_analysis_functions_names_duplicated = functions names are duplicated
     .note = all `#[rustc_must_implement_one_of]` arguments must be unique
 
+hir_analysis_generic_args_on_overridden_impl = could not resolve generic parameters on overridden impl
+
 hir_analysis_impl_not_marked_default = `{$ident}` specializes an item from a parent `impl`, but that item is not marked `default`
     .label = cannot specialize default item `{$ident}`
     .ok_label = parent `impl` is here
@@ -387,8 +389,6 @@ hir_analysis_static_mut_ref_lint = {$shared}reference of mutable static is disco
 
 hir_analysis_static_specialize = cannot specialize on `'static` lifetime
 
-hir_analysis_substs_on_overridden_impl = could not resolve substs on overridden impl
-
 hir_analysis_tait_forward_compat = item constrains opaque type that is not in its signature
     .note = this item must mention the opaque type in its signature in order to be able to register hidden types