Use clippy_utils::ty::ty_from_hir_ty to avoid ICE

Author: tesuji

clippy_lints/src/use_self.rs

@@ -2,7 +2,7 @@ use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::is_from_proc_macro;
 use clippy_utils::msrvs::{self, Msrv};
-use clippy_utils::ty::same_type_and_consts;
+use clippy_utils::ty::{same_type_and_consts, ty_from_hir_ty};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
 use rustc_hir::def::{CtorOf, DefKind, Res};
@@ -12,7 +12,6 @@ use rustc_hir::{
     self as hir, AmbigArg, Expr, ExprKind, FnRetTy, FnSig, GenericArgsParentheses, GenericParam, GenericParamKind,
     HirId, Impl, ImplItemKind, Item, ItemKind, Pat, PatKind, Path, QPath, Ty, TyKind,
 };
-use rustc_hir_analysis::lower_ty;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::Ty as MiddleTy;
 use rustc_session::impl_lint_pass;
@@ -73,7 +72,6 @@ impl UseSelf {
 enum StackItem {
     Check {
         impl_id: LocalDefId,
-        in_body: u32,
         types_to_skip: FxHashSet<HirId>,
     },
     NoCheck,
@@ -117,7 +115,6 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
                 .collect();
             StackItem::Check {
                 impl_id: item.owner_id.def_id,
-                in_body: 0,
                 types_to_skip,
             }
         } else {
@@ -186,27 +183,12 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
         }
     }
 
-    fn check_body(&mut self, _: &LateContext<'_>, _: &hir::Body<'_>) {
-        // `lower_ty` cannot be called in `Body`s or it will panic (sometimes). But in bodies
-        // we can use `cx.typeck_results.node_type(..)` to get the `ty::Ty` from a `hir::Ty`.
-        // However the `node_type()` method can *only* be called in bodies.
-        if let Some(&mut StackItem::Check { ref mut in_body, .. }) = self.stack.last_mut() {
-            *in_body = in_body.saturating_add(1);
-        }
-    }
-
-    fn check_body_post(&mut self, _: &LateContext<'_>, _: &hir::Body<'_>) {
-        if let Some(&mut StackItem::Check { ref mut in_body, .. }) = self.stack.last_mut() {
-            *in_body = in_body.saturating_sub(1);
-        }
-    }
 
     fn check_ty(&mut self, cx: &LateContext<'tcx>, hir_ty: &Ty<'tcx, AmbigArg>) {
         if !hir_ty.span.from_expansion()
             && self.msrv.meets(msrvs::TYPE_ALIAS_ENUM_VARIANTS)
             && let Some(&StackItem::Check {
                 impl_id,
-                in_body,
                 ref types_to_skip,
             }) = self.stack.last()
             && let TyKind::Path(QPath::Resolved(_, path)) = hir_ty.kind
@@ -215,12 +197,7 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
                 Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } | Res::Def(DefKind::TyParam, _)
             )
             && !types_to_skip.contains(&hir_ty.hir_id)
-            && let ty = if in_body > 0 {
-                cx.typeck_results().node_type(hir_ty.hir_id)
-            } else {
-                // We don't care about ignoring infer vars here
-                lower_ty(cx.tcx, hir_ty.as_unambig_ty())
-            }
+            && let ty = ty_from_hir_ty(cx, hir_ty)
             && let impl_ty = cx.tcx.type_of(impl_id).instantiate_identity()
             && same_type_and_consts(ty, impl_ty)
             // Ensure the type we encounter and the one from the impl have the same lifetime parameters. It may be that