Auto merge of #122021 - oli-obk:delangitemification, r=compiler-errors

Use hir::Node helper methods instead of repeating the same impl multiple times

I wanted to do something entirely different and stumbled upon a bunch of cleanups

8 files changed, 55 insertions, 185 deletions

diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 186b8716d9a..bcd1e547d3d 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -3640,35 +3640,42 @@ impl<'hir> Node<'hir> {
         }
     }
 
-    pub fn body_id(&self) -> Option<BodyId> {
+    #[inline]
+    pub fn associated_body(&self) -> Option<(LocalDefId, BodyId)> {
         match self {
             Node::Item(Item {
+                owner_id,
                 kind:
-                    ItemKind::Static(_, _, body)
-                    | ItemKind::Const(_, _, body)
-                    | ItemKind::Fn(_, _, body),
+                    ItemKind::Const(_, _, body) | ItemKind::Static(.., body) | ItemKind::Fn(.., body),
                 ..
             })
             | Node::TraitItem(TraitItem {
+                owner_id,
                 kind:
-                    TraitItemKind::Fn(_, TraitFn::Provided(body)) | TraitItemKind::Const(_, Some(body)),
+                    TraitItemKind::Const(_, Some(body)) | TraitItemKind::Fn(_, TraitFn::Provided(body)),
                 ..
             })
             | Node::ImplItem(ImplItem {
-                kind: ImplItemKind::Fn(_, body) | ImplItemKind::Const(_, body),
-                ..
-            })
-            | Node::Expr(Expr {
-                kind:
-                    ExprKind::ConstBlock(ConstBlock { body, .. })
-                    | ExprKind::Closure(Closure { body, .. })
-                    | ExprKind::Repeat(_, ArrayLen::Body(AnonConst { body, .. })),
+                owner_id,
+                kind: ImplItemKind::Const(_, body) | ImplItemKind::Fn(_, body),
                 ..
-            }) => Some(*body),
+            }) => Some((owner_id.def_id, *body)),
+
+            Node::Expr(Expr { kind: ExprKind::Closure(Closure { def_id, body, .. }), .. }) => {
+                Some((*def_id, *body))
+            }
+
+            Node::AnonConst(constant) => Some((constant.def_id, constant.body)),
+            Node::ConstBlock(constant) => Some((constant.def_id, constant.body)),
+
             _ => None,
         }
     }
 
+    pub fn body_id(&self) -> Option<BodyId> {
+        Some(self.associated_body()?.1)
+    }
+
     pub fn generics(self) -> Option<&'hir Generics<'hir>> {
         match self {
             Node::ForeignItem(ForeignItem {
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
index c86788db988..bc6abc53cad 100644
--- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -508,29 +508,9 @@ fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<S
         visitor.has_late_bound_regions
     }
 
-    match node {
-        Node::TraitItem(item) => match &item.kind {
-            hir::TraitItemKind::Fn(sig, _) => has_late_bound_regions(tcx, item.generics, sig.decl),
-            _ => None,
-        },
-        Node::ImplItem(item) => match &item.kind {
-            hir::ImplItemKind::Fn(sig, _) => has_late_bound_regions(tcx, item.generics, sig.decl),
-            _ => None,
-        },
-        Node::ForeignItem(item) => match item.kind {
-            hir::ForeignItemKind::Fn(fn_decl, _, generics) => {
-                has_late_bound_regions(tcx, generics, fn_decl)
-            }
-            _ => None,
-        },
-        Node::Item(item) => match &item.kind {
-            hir::ItemKind::Fn(sig, .., generics, _) => {
-                has_late_bound_regions(tcx, generics, sig.decl)
-            }
-            _ => None,
-        },
-        _ => None,
-    }
+    let decl = node.fn_decl()?;
+    let generics = node.generics()?;
+    has_late_bound_regions(tcx, generics, decl)
 }
 
 struct AnonConstInParamTyDetector {
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index 6aae4aa21b8..66c9fb93500 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -123,43 +123,22 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
     // Preserving the order of insertion is important here so as not to break UI tests.
     let mut predicates: FxIndexSet<(ty::Clause<'_>, Span)> = FxIndexSet::default();
 
-    let ast_generics = match node {
-        Node::TraitItem(item) => item.generics,
-
-        Node::ImplItem(item) => item.generics,
-
-        Node::Item(item) => match item.kind {
+    let ast_generics = node.generics().unwrap_or(NO_GENERICS);
+    if let Node::Item(item) = node {
+        match item.kind {
             ItemKind::Impl(impl_) => {
                 if impl_.defaultness.is_default() {
                     is_default_impl_trait = tcx
                         .impl_trait_ref(def_id)
                         .map(|t| ty::Binder::dummy(t.instantiate_identity()));
                 }
-                impl_.generics
             }
-            ItemKind::Fn(.., generics, _)
-            | ItemKind::TyAlias(_, generics)
-            | ItemKind::Const(_, generics, _)
-            | ItemKind::Enum(_, generics)
-            | ItemKind::Struct(_, generics)
-            | ItemKind::Union(_, generics) => generics,
-
-            ItemKind::Trait(_, _, generics, self_bounds, ..)
-            | ItemKind::TraitAlias(generics, self_bounds) => {
+
+            ItemKind::Trait(_, _, _, self_bounds, ..) | ItemKind::TraitAlias(_, self_bounds) => {
                 is_trait = Some(self_bounds);
-                generics
             }
-            ItemKind::OpaqueTy(OpaqueTy { generics, .. }) => generics,
-            _ => NO_GENERICS,
-        },
-
-        Node::ForeignItem(item) => match item.kind {
-            ForeignItemKind::Static(..) => NO_GENERICS,
-            ForeignItemKind::Fn(_, _, generics) => generics,
-            ForeignItemKind::Type => NO_GENERICS,
-        },
-
-        _ => NO_GENERICS,
+            _ => {}
+        }
     };
 
     let generics = tcx.generics_of(def_id);
@@ -703,45 +682,17 @@ pub(super) fn type_param_predicates(
     let mut extend = None;
 
     let item_hir_id = tcx.local_def_id_to_hir_id(item_def_id);
-    let ast_generics = match tcx.hir_node(item_hir_id) {
-        Node::TraitItem(item) => item.generics,
-
-        Node::ImplItem(item) => item.generics,
-
-        Node::Item(item) => {
-            match item.kind {
-                ItemKind::Fn(.., generics, _)
-                | ItemKind::Impl(&hir::Impl { generics, .. })
-                | ItemKind::TyAlias(_, generics)
-                | ItemKind::Const(_, generics, _)
-                | ItemKind::OpaqueTy(&OpaqueTy {
-                    generics,
-                    origin: hir::OpaqueTyOrigin::TyAlias { .. },
-                    ..
-                })
-                | ItemKind::Enum(_, generics)
-                | ItemKind::Struct(_, generics)
-                | ItemKind::Union(_, generics) => generics,
-                ItemKind::Trait(_, _, generics, ..) => {
-                    // Implied `Self: Trait` and supertrait bounds.
-                    if param_id == item_hir_id {
-                        let identity_trait_ref =
-                            ty::TraitRef::identity(tcx, item_def_id.to_def_id());
-                        extend = Some((identity_trait_ref.to_predicate(tcx), item.span));
-                    }
-                    generics
-                }
-                _ => return result,
-            }
-        }
-
-        Node::ForeignItem(item) => match item.kind {
-            ForeignItemKind::Fn(_, _, generics) => generics,
-            _ => return result,
-        },
 
-        _ => return result,
-    };
+    let hir_node = tcx.hir_node(item_hir_id);
+    let Some(ast_generics) = hir_node.generics() else { return result };
+    if let Node::Item(item) = hir_node
+        && let ItemKind::Trait(..) = item.kind
+        // Implied `Self: Trait` and supertrait bounds.
+        && param_id == item_hir_id
+    {
+        let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id.to_def_id());
+        extend = Some((identity_trait_ref.to_predicate(tcx), item.span));
+    }
 
     let icx = ItemCtxt::new(tcx, item_def_id);
     let extra_predicates = extend.into_iter().chain(
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index d86b4912c89..bc6e09addce 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -95,29 +95,7 @@ macro_rules! type_error_struct {
 fn primary_body_of(
     node: Node<'_>,
 ) -> Option<(hir::BodyId, Option<&hir::Ty<'_>>, Option<&hir::FnSig<'_>>)> {
-    match node {
-        Node::Item(item) => match item.kind {
-            hir::ItemKind::Const(ty, _, body) | hir::ItemKind::Static(ty, _, body) => {
-                Some((body, Some(ty), None))
-            }
-            hir::ItemKind::Fn(ref sig, .., body) => Some((body, None, Some(sig))),
-            _ => None,
-        },
-        Node::TraitItem(item) => match item.kind {
-            hir::TraitItemKind::Const(ty, Some(body)) => Some((body, Some(ty), None)),
-            hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
-                Some((body, None, Some(sig)))
-            }
-            _ => None,
-        },
-        Node::ImplItem(item) => match item.kind {
-            hir::ImplItemKind::Const(ty, body) => Some((body, Some(ty), None)),
-            hir::ImplItemKind::Fn(ref sig, body) => Some((body, None, Some(sig))),
-            _ => None,
-        },
-        Node::AnonConst(constant) => Some((constant.body, None, None)),
-        _ => None,
-    }
+    Some((node.body_id()?, node.ty(), node.fn_sig()))
 }
 
 fn has_typeck_results(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 5043bd855cc..ed05ffef205 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -20,44 +20,6 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_target::spec::abi::Abi;
 
-#[inline]
-pub fn associated_body(node: Node<'_>) -> Option<(LocalDefId, BodyId)> {
-    match node {
-        Node::Item(Item {
-            owner_id,
-            kind: ItemKind::Const(_, _, body) | ItemKind::Static(.., body) | ItemKind::Fn(.., body),
-            ..
-        })
-        | Node::TraitItem(TraitItem {
-            owner_id,
-            kind:
-                TraitItemKind::Const(_, Some(body)) | TraitItemKind::Fn(_, TraitFn::Provided(body)),
-            ..
-        })
-        | Node::ImplItem(ImplItem {
-            owner_id,
-            kind: ImplItemKind::Const(_, body) | ImplItemKind::Fn(_, body),
-            ..
-        }) => Some((owner_id.def_id, *body)),
-
-        Node::Expr(Expr { kind: ExprKind::Closure(Closure { def_id, body, .. }), .. }) => {
-            Some((*def_id, *body))
-        }
-
-        Node::AnonConst(constant) => Some((constant.def_id, constant.body)),
-        Node::ConstBlock(constant) => Some((constant.def_id, constant.body)),
-
-        _ => None,
-    }
-}
-
-fn is_body_owner(node: Node<'_>, hir_id: HirId) -> bool {
-    match associated_body(node) {
-        Some((_, b)) => b.hir_id == hir_id,
-        None => false,
-    }
-}
-
 // FIXME: the structure was necessary in the past but now it
 // only serves as "namespace" for HIR-related methods, and can be
 // removed if all the methods are reasonably renamed and moved to tcx
@@ -273,7 +235,7 @@ impl<'hir> Map<'hir> {
     #[track_caller]
     pub fn enclosing_body_owner(self, hir_id: HirId) -> LocalDefId {
         for (_, node) in self.parent_iter(hir_id) {
-            if let Some((def_id, _)) = associated_body(node) {
+            if let Some((def_id, _)) = node.associated_body() {
                 return def_id;
             }
         }
@@ -286,20 +248,18 @@ impl<'hir> Map<'hir> {
     /// item (possibly associated), a closure, or a `hir::AnonConst`.
     pub fn body_owner(self, BodyId { hir_id }: BodyId) -> HirId {
         let parent = self.tcx.parent_hir_id(hir_id);
-        assert!(is_body_owner(self.tcx.hir_node(parent), hir_id), "{hir_id:?}");
+        assert_eq!(self.tcx.hir_node(parent).body_id().unwrap().hir_id, hir_id, "{hir_id:?}");
         parent
     }
 
     pub fn body_owner_def_id(self, BodyId { hir_id }: BodyId) -> LocalDefId {
-        associated_body(self.tcx.parent_hir_node(hir_id)).unwrap().0
+        self.tcx.parent_hir_node(hir_id).associated_body().unwrap().0
     }
 
     /// Given a `LocalDefId`, returns the `BodyId` associated with it,
     /// if the node is a body owner, otherwise returns `None`.
     pub fn maybe_body_owned_by(self, id: LocalDefId) -> Option<BodyId> {
-        let node = self.tcx.hir_node_by_def_id(id);
-        let (_, body_id) = associated_body(node)?;
-        Some(body_id)
+        self.tcx.hir_node_by_def_id(id).body_id()
     }
 
     /// Given a body owner's id, returns the `BodyId` associated with it.
@@ -1314,7 +1274,7 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
     }
 
     fn visit_item(&mut self, item: &'hir Item<'hir>) {
-        if associated_body(Node::Item(item)).is_some() {
+        if Node::Item(item).associated_body().is_some() {
             self.body_owners.push(item.owner_id.def_id);
         }
 
@@ -1355,7 +1315,7 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
     }
 
     fn visit_trait_item(&mut self, item: &'hir TraitItem<'hir>) {
-        if associated_body(Node::TraitItem(item)).is_some() {
+        if Node::TraitItem(item).associated_body().is_some() {
             self.body_owners.push(item.owner_id.def_id);
         }
 
@@ -1364,7 +1324,7 @@ impl<'hir> Visitor<'hir> for ItemCollector<'hir> {
     }
 
     fn visit_impl_item(&mut self, item: &'hir ImplItem<'hir>) {
-        if associated_body(Node::ImplItem(item)).is_some() {
+        if Node::ImplItem(item).associated_body().is_some() {
             self.body_owners.push(item.owner_id.def_id);
         }
 
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index b2407c54507..83189c6a50a 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -13,7 +13,6 @@ use self::spans::{BcbMapping, BcbMappingKind, CoverageSpans};
 
 use crate::MirPass;
 
-use rustc_middle::hir;
 use rustc_middle::mir::coverage::*;
 use rustc_middle::mir::{
     self, BasicBlock, BasicBlockData, Coverage, SourceInfo, Statement, StatementKind, Terminator,
@@ -368,8 +367,7 @@ fn extract_hir_info<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> ExtractedHir
     // to HIR for it.
 
     let hir_node = tcx.hir_node_by_def_id(def_id);
-    let (_, fn_body_id) =
-        hir::map::associated_body(hir_node).expect("HIR node is a function with body");
+    let fn_body_id = hir_node.body_id().expect("HIR node is a function with body");
     let hir_body = tcx.hir().body(fn_body_id);
 
     let maybe_fn_sig = hir_node.fn_sig();
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index eb2399f7a64..1254ae8cfc8 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -609,13 +609,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     && !self.tcx.sess.target.is_like_wasm
                     && !self.tcx.sess.opts.actually_rustdoc
                 {
-                    let hir::Node::Item(item) = self.tcx.hir_node(hir_id) else {
-                        unreachable!();
-                    };
-                    let hir::ItemKind::Fn(sig, _, _) = item.kind else {
-                        // target is `Fn`
-                        unreachable!();
-                    };
+                    let sig = self.tcx.hir_node(hir_id).fn_sig().unwrap();
 
                     self.dcx().emit_err(errors::LangItemWithTargetFeature {
                         attr_span: attr.span,
diff --git a/src/tools/clippy/clippy_lints/src/needless_pass_by_ref_mut.rs b/src/tools/clippy/clippy_lints/src/needless_pass_by_ref_mut.rs
index a450dee3050..30d3e86dc4e 100644
--- a/src/tools/clippy/clippy_lints/src/needless_pass_by_ref_mut.rs
+++ b/src/tools/clippy/clippy_lints/src/needless_pass_by_ref_mut.rs
@@ -13,7 +13,6 @@ use rustc_hir::{
 use rustc_hir_typeck::expr_use_visitor as euv;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::hir::map::associated_body;
 use rustc_middle::mir::FakeReadCause;
 use rustc_middle::ty::{self, Ty, TyCtxt, UpvarId, UpvarPath};
 use rustc_session::impl_lint_pass;
@@ -112,7 +111,10 @@ fn check_closures<'tcx>(
         }
         ctx.prev_bind = None;
         ctx.prev_move_to_closure.clear();
-        if let Some(body) = associated_body(cx.tcx.hir_node_by_def_id(closure))
+        if let Some(body) = cx
+            .tcx
+            .hir_node_by_def_id(closure)
+            .associated_body()
             .map(|(_, body_id)| hir.body(body_id))
         {
             euv::ExprUseVisitor::new(ctx, infcx, closure, cx.param_env, cx.typeck_results()).consume_body(body);