Rollup merge of #96471 - BoxyUwU:let_else_considered_harmful, r=lcnr

replace let else with `?`

r? `@oli-obk`

compiler/rustc_expand/src/base.rs

@@ -1272,9 +1272,7 @@ pub fn parse_macro_name_and_helper_attrs(
     // Once we've located the `#[proc_macro_derive]` attribute, verify
     // that it's of the form `#[proc_macro_derive(Foo)]` or
     // `#[proc_macro_derive(Foo, attributes(A, ..))]`
-    let Some(list) = attr.meta_item_list() else {
-        return None;
-    };
+    let list = attr.meta_item_list()?;
     if list.len() != 1 && list.len() != 2 {
         diag.span_err(attr.span, "attribute must have either one or two arguments");
         return None;

compiler/rustc_index/src/bit_set.rs

@@ -1714,7 +1714,7 @@ impl<R: Idx, C: Idx> SparseBitMatrix<R, C> {
     }
 
     pub fn row(&self, row: R) -> Option<&HybridBitSet<C>> {
-        if let Some(Some(row)) = self.rows.get(row) { Some(row) } else { None }
+        self.rows.get(row)?.as_ref()
     }
 
     /// Intersects `row` with `set`. `set` can be either `BitSet` or

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -25,21 +25,16 @@ pub(crate) fn find_anon_type<'tcx>(
     region: Region<'tcx>,
     br: &ty::BoundRegionKind,
 ) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnSig<'tcx>)> {
-    if let Some(anon_reg) = tcx.is_suitable_region(region) {
-        let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
-        let Some(fn_sig) = tcx.hir().get(hir_id).fn_sig() else {
-            return None
-        };
+    let anon_reg = tcx.is_suitable_region(region)?;
+    let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
+    let fn_sig = tcx.hir().get(hir_id).fn_sig()?;
 
-        fn_sig
-            .decl
-            .inputs
-            .iter()
-            .find_map(|arg| find_component_for_bound_region(tcx, arg, br))
-            .map(|ty| (ty, fn_sig))
-    } else {
-        None
-    }
+    fn_sig
+        .decl
+        .inputs
+        .iter()
+        .find_map(|arg| find_component_for_bound_region(tcx, arg, br))
+        .map(|ty| (ty, fn_sig))
 }
 
 // This method creates a FindNestedTypeVisitor which returns the type corresponding

compiler/rustc_mir_transform/src/early_otherwise_branch.rs

@@ -336,9 +336,7 @@ fn evaluate_candidate<'tcx>(
             Some(poss)
         }
     };
-    let Some((_, child)) = targets.iter().next() else {
-        return None
-    };
+    let (_, child) = targets.iter().next()?;
     let child_terminator = &bbs[child].terminator();
     let TerminatorKind::SwitchInt {
         switch_ty: child_ty,

compiler/rustc_parse/src/lexer/unicode_chars.rs

@@ -338,9 +338,7 @@ pub(super) fn check_for_substitution<'a>(
     ch: char,
     err: &mut Diagnostic,
 ) -> Option<token::TokenKind> {
-    let Some(&(_u_char, u_name, ascii_char)) = UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch) else {
-        return None;
-    };
+    let &(_u_char, u_name, ascii_char) = UNICODE_ARRAY.iter().find(|&&(c, _, _)| c == ch)?;
 
     let span = Span::with_root_ctxt(pos, pos + Pos::from_usize(ch.len_utf8()));
 

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1183,9 +1183,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         ident: Symbol,
         kind: &AssocItemKind,
     ) -> Option<Symbol> {
-        let Some((module, _)) = &self.current_trait_ref else {
-            return None;
-        };
+        let (module, _) = self.current_trait_ref.as_ref()?;
         if ident == kw::Underscore {
             // We do nothing for `_`.
             return None;

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -757,7 +757,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         formal_args: &[Ty<'tcx>],
     ) -> Option<Vec<Ty<'tcx>>> {
         let formal_ret = self.resolve_vars_with_obligations(formal_ret);
-        let Some(ret_ty) = expected_ret.only_has_type(self) else { return None };
+        let ret_ty = expected_ret.only_has_type(self)?;
 
         // HACK(oli-obk): This is a hack to keep RPIT and TAIT in sync wrt their behaviour.
         // Without it, the inference

src/librustdoc/clean/mod.rs

@@ -1305,7 +1305,7 @@ fn clean_qpath(hir_ty: &hir::Ty<'_>, cx: &mut DocContext<'_>) -> Type {
 fn maybe_expand_private_type_alias(cx: &mut DocContext<'_>, path: &hir::Path<'_>) -> Option<Type> {
     let Res::Def(DefKind::TyAlias, def_id) = path.res else { return None };
     // Substitute private type aliases
-    let Some(def_id) = def_id.as_local() else { return None };
+    let def_id = def_id.as_local()?;
     let alias = if !cx.cache.access_levels.is_exported(def_id.to_def_id()) {
         &cx.tcx.hir().expect_item(def_id).kind
     } else {