Newtype for AscribeUserType semi-traversable tuple

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1247,7 +1247,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     );
                 }
             }
-            StatementKind::AscribeUserType(box (place, projection), variance) => {
+            StatementKind::AscribeUserType(box AscribeUserType(place, projection), variance) => {
                 let place_ty = place.ty(body, tcx).ty;
                 if let Err(terr) = self.relate_type_and_user_type(
                     place_ty,

compiler/rustc_middle/src/mir/mod.rs

@@ -1457,7 +1457,7 @@ impl Debug for Statement<'_> {
             PlaceMention(ref place) => {
                 write!(fmt, "PlaceMention({:?})", place)
             }
-            AscribeUserType(box (ref place, ref c_ty), ref variance) => {
+            AscribeUserType(box self::AscribeUserType(ref place, ref c_ty), ref variance) => {
                 write!(fmt, "AscribeUserType({:?}, {:?}, {:?})", place, variance, c_ty)
             }
             Coverage(box self::Coverage { ref kind, code_region: Some(ref rgn) }) => {
@@ -2693,6 +2693,10 @@ impl<'tcx> UserTypeProjections {
     }
 }
 
+#[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
+#[derive(TypeFoldable, TypeVisitable)]
+pub struct AscribeUserType<'tcx>(pub Place<'tcx>, pub UserTypeProjection);
+
 /// Encodes the effect of a user-supplied type annotation on the
 /// subcomponents of a pattern. The effect is determined by applying the
 /// given list of projections to some underlying base type. Often,
@@ -2709,7 +2713,6 @@ impl<'tcx> UserTypeProjections {
 ///   `field[0]` (aka `.0`), indicating that the type of `s` is
 ///   determined by finding the type of the `.0` field from `T`.
 #[derive(Clone, Debug, TyEncodable, TyDecodable, Hash, HashStable, PartialEq)]
-#[derive(TypeFoldable, TypeVisitable)]
 pub struct UserTypeProjection {
     pub base: UserTypeAnnotationIndex,
     pub projs: Vec<ProjectionKind>,

compiler/rustc_middle/src/mir/syntax.rs

@@ -3,7 +3,7 @@
 //! This is in a dedicated file so that changes to this file can be reviewed more carefully.
 //! The intention is that this file only contains datatype declarations, no code.
 
-use super::{BasicBlock, Constant, Field, Local, SwitchTargets, UserTypeProjection};
+use super::{AscribeUserType, BasicBlock, Constant, Field, Local, SwitchTargets};
 
 use crate::mir::coverage::{CodeRegion, CoverageKind};
 use crate::traits::Reveal;
@@ -350,7 +350,7 @@ pub enum StatementKind<'tcx> {
     /// When executed at runtime this is a nop.
     ///
     /// Disallowed after drop elaboration.
-    AscribeUserType(Box<(Place<'tcx>, UserTypeProjection)>, ty::Variance),
+    AscribeUserType(Box<AscribeUserType<'tcx>>, ty::Variance),
 
     /// Marks the start of a "coverage region", injected with '-Cinstrument-coverage'. A
     /// `Coverage` statement carries metadata about the coverage region, used to inject a coverage

compiler/rustc_middle/src/mir/visit.rs

@@ -413,7 +413,7 @@ macro_rules! make_mir_visitor {
                         );
                     }
                     StatementKind::AscribeUserType(
-                        box (place, user_ty),
+                        box AscribeUserType(place, user_ty),
                         variance
                     ) => {
                         self.visit_ascribe_user_ty(place, $(& $mutability)? *variance, user_ty, location);

compiler/rustc_mir_build/src/build/expr/as_place.rs

@@ -487,7 +487,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         Statement {
                             source_info,
                             kind: StatementKind::AscribeUserType(
-                                Box::new((
+                                Box::new(AscribeUserType(
                                     place,
                                     UserTypeProjection { base: annotation_index, projs: vec![] },
                                 )),
@@ -514,7 +514,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         Statement {
                             source_info,
                             kind: StatementKind::AscribeUserType(
-                                Box::new((
+                                Box::new(AscribeUserType(
                                     Place::from(temp),
                                     UserTypeProjection { base: annotation_index, projs: vec![] },
                                 )),

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -530,7 +530,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     Statement {
                         source_info: ty_source_info,
                         kind: StatementKind::AscribeUserType(
-                            Box::new((place, UserTypeProjection { base, projs: Vec::new() })),
+                            Box::new(AscribeUserType(
+                                place,
+                                UserTypeProjection { base, projs: Vec::new() },
+                            )),
                             // We always use invariant as the variance here. This is because the
                             // variance field from the ascription refers to the variance to use
                             // when applying the type to the value being matched, but this
@@ -2087,7 +2090,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Statement {
                     source_info,
                     kind: StatementKind::AscribeUserType(
-                        Box::new((
+                        Box::new(AscribeUserType(
                             ascription.source,
                             UserTypeProjection { base, projs: Vec::new() },
                         )),

compiler/rustc_mir_transform/src/remove_zsts.rs

@@ -116,7 +116,7 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
             }
             StatementKind::Deinit(box place)
             | StatementKind::SetDiscriminant { box place, variant_index: _ }
-            | StatementKind::AscribeUserType(box (place, _), _)
+            | StatementKind::AscribeUserType(box AscribeUserType(place, _), _)
             | StatementKind::Retag(_, box place)
             | StatementKind::PlaceMention(box place)
             | StatementKind::FakeRead(box FakeReadCauseAndPlace(_, place)) => Some(place),