Rollup merge of rust-lang#136219 - yotamofek:pr/hir-cleanup, r=compiler-errors

Misc. `rustc_hir` cleanups 🧹

Each commit stands on its own, but I think all of them make the code a bit cleaner

Author: matthiaskrgr

compiler/rustc_hir/src/hir.rs

@@ -206,7 +206,7 @@ pub type UsePath<'hir> = Path<'hir, SmallVec<[Res; 3]>>;
 
 impl Path<'_> {
     pub fn is_global(&self) -> bool {
-        !self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
+        self.segments.first().is_some_and(|segment| segment.ident.name == kw::PathRoot)
     }
 }
 
@@ -1061,10 +1061,7 @@ impl Attribute {
 
     pub fn value_lit(&self) -> Option<&MetaItemLit> {
         match &self.kind {
-            AttrKind::Normal(n) => match n.as_ref() {
-                AttrItem { args: AttrArgs::Eq { expr, .. }, .. } => Some(expr),
-                _ => None,
-            },
+            AttrKind::Normal(box AttrItem { args: AttrArgs::Eq { expr, .. }, .. }) => Some(expr),
             _ => None,
         }
     }
@@ -1077,12 +1074,9 @@ impl AttributeExt for Attribute {
 
     fn meta_item_list(&self) -> Option<ThinVec<ast::MetaItemInner>> {
         match &self.kind {
-            AttrKind::Normal(n) => match n.as_ref() {
-                AttrItem { args: AttrArgs::Delimited(d), .. } => {
-                    ast::MetaItemKind::list_from_tokens(d.tokens.clone())
-                }
-                _ => None,
-            },
+            AttrKind::Normal(box AttrItem { args: AttrArgs::Delimited(d), .. }) => {
+                ast::MetaItemKind::list_from_tokens(d.tokens.clone())
+            }
             _ => None,
         }
     }
@@ -1098,23 +1092,16 @@ impl AttributeExt for Attribute {
     /// For a single-segment attribute, returns its name; otherwise, returns `None`.
     fn ident(&self) -> Option<Ident> {
         match &self.kind {
-            AttrKind::Normal(n) => {
-                if let [ident] = n.path.segments.as_ref() {
-                    Some(*ident)
-                } else {
-                    None
-                }
-            }
-            AttrKind::DocComment(..) => None,
+            AttrKind::Normal(box AttrItem {
+                path: AttrPath { segments: box [ident], .. }, ..
+            }) => Some(*ident),
+            _ => None,
         }
     }
 
     fn path_matches(&self, name: &[Symbol]) -> bool {
         match &self.kind {
-            AttrKind::Normal(n) => {
-                n.path.segments.len() == name.len()
-                    && n.path.segments.iter().zip(name).all(|(s, n)| s.name == *n)
-            }
+            AttrKind::Normal(n) => n.path.segments.iter().map(|segment| &segment.name).eq(name),
             AttrKind::DocComment(..) => false,
         }
     }
@@ -1128,12 +1115,7 @@ impl AttributeExt for Attribute {
     }
 
     fn is_word(&self) -> bool {
-        match &self.kind {
-            AttrKind::Normal(n) => {
-                matches!(n.args, AttrArgs::Empty)
-            }
-            AttrKind::DocComment(..) => false,
-        }
+        matches!(self.kind, AttrKind::Normal(box AttrItem { args: AttrArgs::Empty, .. }))
     }
 
     fn ident_path(&self) -> Option<SmallVec<[Ident; 1]>> {
@@ -1990,7 +1972,7 @@ impl fmt::Display for ConstContext {
 }
 
 // NOTE: `IntoDiagArg` impl for `ConstContext` lives in `rustc_errors`
-// due to a cyclical dependency between hir that crate.
+// due to a cyclical dependency between hir and that crate.
 
 /// A literal.
 pub type Lit = Spanned<LitKind>;
@@ -3604,10 +3586,10 @@ impl<'hir> FnRetTy<'hir> {
     }
 
     pub fn is_suggestable_infer_ty(&self) -> Option<&'hir Ty<'hir>> {
-        if let Self::Return(ty) = self {
-            if ty.is_suggestable_infer_ty() {
-                return Some(*ty);
-            }
+        if let Self::Return(ty) = self
+            && ty.is_suggestable_infer_ty()
+        {
+            return Some(*ty);
         }
         None
     }
@@ -3976,11 +3958,11 @@ pub struct FnHeader {
 
 impl FnHeader {
     pub fn is_async(&self) -> bool {
-        matches!(&self.asyncness, IsAsync::Async(_))
+        matches!(self.asyncness, IsAsync::Async(_))
     }
 
     pub fn is_const(&self) -> bool {
-        matches!(&self.constness, Constness::Const)
+        matches!(self.constness, Constness::Const)
     }
 
     pub fn is_unsafe(&self) -> bool {
@@ -4076,16 +4058,16 @@ pub struct Impl<'hir> {
 
 impl ItemKind<'_> {
     pub fn generics(&self) -> Option<&Generics<'_>> {
-        Some(match *self {
-            ItemKind::Fn { ref generics, .. }
-            | ItemKind::TyAlias(_, ref generics)
-            | ItemKind::Const(_, ref generics, _)
-            | ItemKind::Enum(_, ref generics)
-            | ItemKind::Struct(_, ref generics)
-            | ItemKind::Union(_, ref generics)
-            | ItemKind::Trait(_, _, ref generics, _, _)
-            | ItemKind::TraitAlias(ref generics, _)
-            | ItemKind::Impl(Impl { ref generics, .. }) => generics,
+        Some(match self {
+            ItemKind::Fn { generics, .. }
+            | ItemKind::TyAlias(_, generics)
+            | ItemKind::Const(_, generics, _)
+            | ItemKind::Enum(_, generics)
+            | ItemKind::Struct(_, generics)
+            | ItemKind::Union(_, generics)
+            | ItemKind::Trait(_, _, generics, _, _)
+            | ItemKind::TraitAlias(generics, _)
+            | ItemKind::Impl(Impl { generics, .. }) => generics,
             _ => return None,
         })
     }
@@ -4484,16 +4466,14 @@ impl<'hir> Node<'hir> {
 
     /// Get a `hir::Impl` if the node is an impl block for the given `trait_def_id`.
     pub fn impl_block_of_trait(self, trait_def_id: DefId) -> Option<&'hir Impl<'hir>> {
-        match self {
-            Node::Item(Item { kind: ItemKind::Impl(impl_block), .. })
-                if impl_block
-                    .of_trait
-                    .and_then(|trait_ref| trait_ref.trait_def_id())
-                    .is_some_and(|trait_id| trait_id == trait_def_id) =>
-            {
-                Some(impl_block)
-            }
-            _ => None,
+        if let Node::Item(Item { kind: ItemKind::Impl(impl_block), .. }) = self
+            && let Some(trait_ref) = impl_block.of_trait
+            && let Some(trait_id) = trait_ref.trait_def_id()
+            && trait_id == trait_def_id
+        {
+            Some(impl_block)
+        } else {
+            None
         }
     }
 

compiler/rustc_hir/src/lib.rs

@@ -5,6 +5,7 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![feature(associated_type_defaults)]
+#![feature(box_patterns)]
 #![feature(closure_track_caller)]
 #![feature(debug_closure_helpers)]
 #![feature(exhaustive_patterns)]