Rollup merge of #108958 - clubby789:unbox-the-hir, r=compiler-errors

Remove box expressions from HIR

After #108516, `#[rustc_box]` is used at HIR->THIR lowering and this is no longer emitted, so it can be removed.

This is based on top of #108471 to help with conflicts, so 43490488ccacd1a822e9c621f5ed6fca99959a0b is the only relevant commit (sorry for all the duplicated pings!)

````@rustbot```` label +S-blocked

clippy_lints/src/infinite_iter.rs

@@ -167,7 +167,7 @@ fn is_infinite(cx: &LateContext<'_>, expr: &Expr<'_>) -> Finiteness {
             Finite
         },
         ExprKind::Block(block, _) => block.expr.as_ref().map_or(Finite, |e| is_infinite(cx, e)),
-        ExprKind::Box(e) | ExprKind::AddrOf(BorrowKind::Ref, _, e) => is_infinite(cx, e),
+        ExprKind::AddrOf(BorrowKind::Ref, _, e) => is_infinite(cx, e),
         ExprKind::Call(path, _) => {
             if let ExprKind::Path(ref qpath) = path.kind {
                 cx.qpath_res(qpath, path.hir_id)

clippy_lints/src/loops/never_loop.rs

@@ -124,8 +124,7 @@ fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<(&'tcx Expr<'tcx>, Option<&'t
 #[allow(clippy::too_many_lines)]
 fn never_loop_expr(expr: &Expr<'_>, ignore_ids: &mut Vec<HirId>, main_loop_id: HirId) -> NeverLoopResult {
     match expr.kind {
-        ExprKind::Box(e)
-        | ExprKind::Unary(_, e)
+        ExprKind::Unary(_, e)
         | ExprKind::Cast(e, _)
         | ExprKind::Type(e, _)
         | ExprKind::Field(e, _)

clippy_lints/src/matches/significant_drop_in_scrutinee.rs

@@ -321,7 +321,6 @@ impl<'a, 'tcx> Visitor<'tcx> for SigDropHelper<'a, 'tcx> {
                     self.has_significant_drop = true;
                 }
             }
-            ExprKind::Box(..) |
             ExprKind::Array(..) |
             ExprKind::Call(..) |
             ExprKind::Unary(..) |

clippy_lints/src/methods/unnecessary_sort_by.rs

@@ -33,10 +33,6 @@ struct SortByKeyDetection {
 /// contains a and the other replaces it with b)
 fn mirrored_exprs(a_expr: &Expr<'_>, a_ident: &Ident, b_expr: &Expr<'_>, b_ident: &Ident) -> bool {
     match (&a_expr.kind, &b_expr.kind) {
-        // Two boxes with mirrored contents
-        (ExprKind::Box(left_expr), ExprKind::Box(right_expr)) => {
-            mirrored_exprs(left_expr, a_ident, right_expr, b_ident)
-        },
         // Two arrays with mirrored contents
         (ExprKind::Array(left_exprs), ExprKind::Array(right_exprs)) => {
             iter::zip(*left_exprs, *right_exprs).all(|(left, right)| mirrored_exprs(left, a_ident, right, b_ident))

clippy_lints/src/no_effect.rs

@@ -127,8 +127,7 @@ fn has_no_effect(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
         | ExprKind::Type(inner, _)
         | ExprKind::Unary(_, inner)
         | ExprKind::Field(inner, _)
-        | ExprKind::AddrOf(_, _, inner)
-        | ExprKind::Box(inner) => has_no_effect(cx, inner),
+        | ExprKind::AddrOf(_, _, inner) => has_no_effect(cx, inner),
         ExprKind::Struct(_, fields, ref base) => {
             !has_drop(cx, cx.typeck_results().expr_ty(expr))
                 && fields.iter().all(|field| has_no_effect(cx, field.expr))
@@ -234,8 +233,7 @@ fn reduce_expression<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<Vec
         | ExprKind::Type(inner, _)
         | ExprKind::Unary(_, inner)
         | ExprKind::Field(inner, _)
-        | ExprKind::AddrOf(_, _, inner)
-        | ExprKind::Box(inner) => reduce_expression(cx, inner).or_else(|| Some(vec![inner])),
+        | ExprKind::AddrOf(_, _, inner) => reduce_expression(cx, inner).or_else(|| Some(vec![inner])),
         ExprKind::Struct(_, fields, ref base) => {
             if has_drop(cx, cx.typeck_results().expr_ty(expr)) {
                 None

clippy_lints/src/shadow.rs

@@ -213,8 +213,7 @@ fn is_self_shadow(cx: &LateContext<'_>, pat: &Pat<'_>, mut expr: &Expr<'_>, hir_
     }
     loop {
         expr = match expr.kind {
-            ExprKind::Box(e)
-            | ExprKind::AddrOf(_, _, e)
+            ExprKind::AddrOf(_, _, e)
             | ExprKind::Block(
                 &Block {
                     stmts: [],

clippy_lints/src/significant_drop_tightening.rs

@@ -380,7 +380,6 @@ impl<'cx, 'sdt, 'tcx> Visitor<'tcx> for SigDropFinder<'cx, 'sdt, 'tcx> {
             | hir::ExprKind::Assign(..)
             | hir::ExprKind::AssignOp(..)
             | hir::ExprKind::Binary(..)
-            | hir::ExprKind::Box(..)
             | hir::ExprKind::Call(..)
             | hir::ExprKind::Field(..)
             | hir::ExprKind::If(..)

clippy_lints/src/utils/author.rs

@@ -395,11 +395,6 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
                 }
                 self.expr(field!(let_expr.init));
             },
-            ExprKind::Box(inner) => {
-                bind!(self, inner);
-                kind!("Box({inner})");
-                self.expr(inner);
-            },
             ExprKind::Array(elements) => {
                 bind!(self, elements);
                 kind!("Array({elements})");

clippy_utils/src/check_proc_macro.rs

@@ -112,7 +112,6 @@ fn qpath_search_pat(path: &QPath<'_>) -> (Pat, Pat) {
 /// Get the search patterns to use for the given expression
 fn expr_search_pat(tcx: TyCtxt<'_>, e: &Expr<'_>) -> (Pat, Pat) {
     match e.kind {
-        ExprKind::Box(e) => (Pat::Str("box"), expr_search_pat(tcx, e).1),
         ExprKind::ConstBlock(_) => (Pat::Str("const"), Pat::Str("}")),
         ExprKind::Tup([]) => (Pat::Str(")"), Pat::Str("(")),
         ExprKind::Unary(UnOp::Deref, e) => (Pat::Str("*"), expr_search_pat(tcx, e).1),

clippy_utils/src/eager_or_lazy.rs

@@ -199,8 +199,7 @@ fn expr_eagerness<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> EagernessS
                 },
 
                 // Memory allocation, custom operator, loop, or call to an unknown function
-                ExprKind::Box(_)
-                | ExprKind::Unary(..)
+                ExprKind::Unary(..)
                 | ExprKind::Binary(..)
                 | ExprKind::Loop(..)
                 | ExprKind::Call(..) => self.eagerness = Lazy,

clippy_utils/src/hir_utils.rs

@@ -249,7 +249,6 @@ impl HirEqInterExpr<'_, '_, '_> {
                 both(&li.label, &ri.label, |l, r| l.ident.name == r.ident.name)
                     && both(le, re, |l, r| self.eq_expr(l, r))
             },
-            (&ExprKind::Box(l), &ExprKind::Box(r)) => self.eq_expr(l, r),
             (&ExprKind::Call(l_fun, l_args), &ExprKind::Call(r_fun, r_args)) => {
                 self.inner.allow_side_effects && self.eq_expr(l_fun, r_fun) && self.eq_exprs(l_args, r_args)
             },
@@ -628,7 +627,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                     self.hash_expr(j);
                 }
             },
-            ExprKind::Box(e) | ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
+            ExprKind::DropTemps(e) | ExprKind::Yield(e, _) => {
                 self.hash_expr(e);
             },
             ExprKind::Call(fun, args) => {

clippy_utils/src/sugg.rs

@@ -133,7 +133,6 @@ impl<'a> Sugg<'a> {
 
         match expr.kind {
             hir::ExprKind::AddrOf(..)
-            | hir::ExprKind::Box(..)
             | hir::ExprKind::If(..)
             | hir::ExprKind::Let(..)
             | hir::ExprKind::Closure { .. }

clippy_utils/src/visitors.rs

@@ -600,7 +600,6 @@ pub fn for_each_unconsumed_temporary<'tcx, B>(
                 helper(typeck, false, e, f)?;
             },
             ExprKind::Block(&Block { expr: Some(e), .. }, _)
-            | ExprKind::Box(e)
             | ExprKind::Cast(e, _)
             | ExprKind::Unary(_, e) => {
                 helper(typeck, true, e, f)?;