Auto merge of rust-lang#130963 - nyurik:opts-rustc, r=<try>

Migrate compiler's `&Option<T>` into `Option<&T>`

Similar to rust-lang#130962 but for the compiler.

Trying out my new lint rust-lang/rust-clippy#13336 - according to the [video](https://www.youtube.com/watch?v=6c7pZYP_iIE), this could lead to some performance and memory optimizations.

compiler/rustc_ast_lowering/src/asm.rs

@@ -198,7 +198,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         if let Some(def_id) = static_def_id {
                             let path = self.lower_qpath(
                                 sym.id,
-                                &sym.qself,
+                                sym.qself.as_ref(),
                                 &sym.path,
                                 ParamMode::Optional,
                                 AllowReturnTypeNotation::No,

compiler/rustc_ast_lowering/src/delegation.rs

@@ -337,7 +337,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         } else {
             let path = self.lower_qpath(
                 delegation.id,
-                &delegation.qself,
+                delegation.qself.as_ref(),
                 &delegation.path,
                 ParamMode::Optional,
                 AllowReturnTypeNotation::No,

compiler/rustc_ast_lowering/src/expr.rs

@@ -278,7 +278,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 ExprKind::Path(qself, path) => {
                     let qpath = self.lower_qpath(
                         e.id,
-                        qself,
+                        qself.as_ref(),
                         path,
                         ParamMode::Optional,
                         AllowReturnTypeNotation::No,
@@ -326,7 +326,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::ExprKind::Struct(
                         self.arena.alloc(self.lower_qpath(
                             e.id,
-                            &se.qself,
+                            se.qself.as_ref(),
                             &se.path,
                             ParamMode::Optional,
                             AllowReturnTypeNotation::No,
@@ -1287,7 +1287,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     );
                     let qpath = self.lower_qpath(
                         callee.id,
-                        qself,
+                        qself.as_ref(),
                         path,
                         ParamMode::Optional,
                         AllowReturnTypeNotation::No,
@@ -1308,7 +1308,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 if let Some((qself, path)) = self.extract_unit_struct_path(lhs) {
                     let qpath = self.lower_qpath(
                         lhs.id,
-                        qself,
+                        qself.as_ref(),
                         path,
                         ParamMode::Optional,
                         AllowReturnTypeNotation::No,
@@ -1334,7 +1334,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 }));
                 let qpath = self.lower_qpath(
                     lhs.id,
-                    &se.qself,
+                    se.qself.as_ref(),
                     &se.path,
                     ParamMode::Optional,
                     AllowReturnTypeNotation::No,

compiler/rustc_ast_lowering/src/format.rs

@@ -283,7 +283,7 @@ fn make_argument<'hir>(
 fn make_count<'hir>(
     ctx: &mut LoweringContext<'_, 'hir>,
     sp: Span,
-    count: &Option<FormatCount>,
+    count: Option<&FormatCount>,
     argmap: &mut FxIndexMap<(usize, ArgumentType), Option<Span>>,
 ) -> hir::Expr<'hir> {
     match count {
@@ -378,8 +378,8 @@ fn make_format_spec<'hir>(
         | ((debug_hex == Some(FormatDebugHex::Lower)) as u32) << 4
         | ((debug_hex == Some(FormatDebugHex::Upper)) as u32) << 5;
     let flags = ctx.expr_u32(sp, flags);
-    let precision = make_count(ctx, sp, precision, argmap);
-    let width = make_count(ctx, sp, width, argmap);
+    let precision = make_count(ctx, sp, precision.as_ref(), argmap);
+    let width = make_count(ctx, sp, width.as_ref(), argmap);
     let format_placeholder_new = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
         sp,
         hir::LangItem::FormatPlaceholder,

compiler/rustc_ast_lowering/src/lib.rs

@@ -1206,7 +1206,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_path_ty(
         &mut self,
         t: &Ty,
-        qself: &Option<ptr::P<QSelf>>,
+        qself: Option<&ptr::P<QSelf>>,
         path: &Path,
         param_mode: ParamMode,
         itctx: ImplTraitContext,
@@ -1340,7 +1340,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 return self.lower_ty_direct(ty, itctx);
             }
             TyKind::Path(qself, path) => {
-                return self.lower_path_ty(t, qself, path, ParamMode::Explicit, itctx);
+                return self.lower_path_ty(t, qself.as_ref(), path, ParamMode::Explicit, itctx);
             }
             TyKind::ImplicitSelf => {
                 let hir_id = self.next_id();
@@ -2222,7 +2222,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     ) -> hir::TraitRef<'hir> {
         let path = match self.lower_qpath(
             p.ref_id,
-            &None,
+            None,
             &p.path,
             ParamMode::Explicit,
             AllowReturnTypeNotation::No,
@@ -2361,7 +2361,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             Res::Def(DefKind::ConstParam, _) => {
                 let qpath = self.lower_qpath(
                     ty_id,
-                    &None,
+                    None,
                     path,
                     ParamMode::Optional,
                     AllowReturnTypeNotation::No,
@@ -2440,7 +2440,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         {
             let qpath = self.lower_qpath(
                 expr.id,
-                qself,
+                qself.as_ref(),
                 path,
                 ParamMode::Optional,
                 AllowReturnTypeNotation::No,

compiler/rustc_ast_lowering/src/pat.rs

@@ -35,7 +35,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     PatKind::TupleStruct(qself, path, pats) => {
                         let qpath = self.lower_qpath(
                             pattern.id,
-                            qself,
+                            qself.as_ref(),
                             path,
                             ParamMode::Optional,
                             AllowReturnTypeNotation::No,
@@ -53,7 +53,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     PatKind::Path(qself, path) => {
                         let qpath = self.lower_qpath(
                             pattern.id,
-                            qself,
+                            qself.as_ref(),
                             path,
                             ParamMode::Optional,
                             AllowReturnTypeNotation::No,
@@ -65,7 +65,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     PatKind::Struct(qself, path, fields, etc) => {
                         let qpath = self.lower_qpath(
                             pattern.id,
-                            qself,
+                            qself.as_ref(),
                             path,
                             ParamMode::Optional,
                             AllowReturnTypeNotation::No,

compiler/rustc_ast_lowering/src/path.rs

@@ -25,7 +25,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     pub(crate) fn lower_qpath(
         &mut self,
         id: NodeId,
-        qself: &Option<ptr::P<QSelf>>,
+        qself: Option<&ptr::P<QSelf>>,
         p: &Path,
         param_mode: ParamMode,
         allow_return_type_notation: AllowReturnTypeNotation,

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1107,9 +1107,9 @@ impl<'a> State<'a> {
         self.commasep_cmnt(b, exprs, |s, e| s.print_expr(e, FixupContext::default()), |e| e.span)
     }
 
-    pub fn print_opt_lifetime(&mut self, lifetime: &Option<ast::Lifetime>) {
-        if let Some(lt) = *lifetime {
-            self.print_lifetime(lt);
+    pub fn print_opt_lifetime(&mut self, lifetime: Option<&ast::Lifetime>) {
+        if let Some(lt) = lifetime {
+            self.print_lifetime(*lt);
             self.nbsp();
         }
     }
@@ -1160,7 +1160,7 @@ impl<'a> State<'a> {
             }
             ast::TyKind::Ref(lifetime, mt) => {
                 self.word("&");
-                self.print_opt_lifetime(lifetime);
+                self.print_opt_lifetime(lifetime.as_ref());
                 self.print_mt(mt, false);
             }
             ast::TyKind::Never => {
@@ -1709,7 +1709,7 @@ impl<'a> State<'a> {
             }
             SelfKind::Region(lt, m) => {
                 self.word("&");
-                self.print_opt_lifetime(lt);
+                self.print_opt_lifetime(lt.as_ref());
                 self.print_mutability(*m, false);
                 self.word("self")
             }

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -151,7 +151,7 @@ impl<'a> State<'a> {
 
     fn print_expr_struct(
         &mut self,
-        qself: &Option<P<ast::QSelf>>,
+        qself: Option<&P<ast::QSelf>>,
         path: &ast::Path,
         fields: &[ast::ExprField],
         rest: &ast::StructRest,
@@ -388,7 +388,7 @@ impl<'a> State<'a> {
                 self.print_expr_repeat(element, count);
             }
             ast::ExprKind::Struct(se) => {
-                self.print_expr_struct(&se.qself, &se.path, &se.fields, &se.rest);
+                self.print_expr_struct(se.qself.as_ref(), &se.path, &se.fields, &se.rest);
             }
             ast::ExprKind::Tup(exprs) => {
                 self.print_expr_tup(exprs);

compiler/rustc_ast_pretty/src/pprust/state/item.rs

@@ -386,18 +386,18 @@ impl<'a> State<'a> {
             ast::ItemKind::Delegation(deleg) => self.print_delegation(
                 &item.attrs,
                 &item.vis,
-                &deleg.qself,
+                deleg.qself.as_ref(),
                 &deleg.path,
                 DelegationKind::Single,
-                &deleg.body,
+                deleg.body.as_ref(),
             ),
             ast::ItemKind::DelegationMac(deleg) => self.print_delegation(
                 &item.attrs,
                 &item.vis,
-                &deleg.qself,
+                deleg.qself.as_ref(),
                 &deleg.prefix,
                 deleg.suffixes.as_ref().map_or(DelegationKind::Glob, |s| DelegationKind::List(s)),
-                &deleg.body,
+                deleg.body.as_ref(),
             ),
         }
         self.ann.post(self, AnnNode::Item(item))
@@ -578,18 +578,18 @@ impl<'a> State<'a> {
             ast::AssocItemKind::Delegation(deleg) => self.print_delegation(
                 &item.attrs,
                 vis,
-                &deleg.qself,
+                deleg.qself.as_ref(),
                 &deleg.path,
                 DelegationKind::Single,
-                &deleg.body,
+                deleg.body.as_ref(),
             ),
             ast::AssocItemKind::DelegationMac(deleg) => self.print_delegation(
                 &item.attrs,
                 vis,
-                &deleg.qself,
+                deleg.qself.as_ref(),
                 &deleg.prefix,
                 deleg.suffixes.as_ref().map_or(DelegationKind::Glob, |s| DelegationKind::List(s)),
-                &deleg.body,
+                deleg.body.as_ref(),
             ),
         }
         self.ann.post(self, AnnNode::SubItem(id))
@@ -599,10 +599,10 @@ impl<'a> State<'a> {
         &mut self,
         attrs: &[ast::Attribute],
         vis: &ast::Visibility,
-        qself: &Option<P<ast::QSelf>>,
+        qself: Option<&P<ast::QSelf>>,
         path: &ast::Path,
         kind: DelegationKind<'_>,
-        body: &Option<P<ast::Block>>,
+        body: Option<&P<ast::Block>>,
     ) {
         if body.is_some() {
             self.head("");

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -2921,7 +2921,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     span,
                     ..
                 },
-            ) => self.report_escaping_data(borrow_span, &name, upvar_span, upvar_name, span),
+            ) => self.report_escaping_data(
+                borrow_span,
+                name.as_deref(),
+                upvar_span,
+                upvar_name,
+                span,
+            ),
             (Some(name), explanation) => self.report_local_value_does_not_live_long_enough(
                 location,
                 &name,
@@ -2973,7 +2979,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 borrow_span,
                 span,
                 category,
-                opt_place_desc.as_ref(),
+                opt_place_desc.as_deref(),
             ) {
                 return diag;
             }
@@ -3315,7 +3321,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         borrow_span: Span,
         return_span: Span,
         category: ConstraintCategory<'tcx>,
-        opt_place_desc: Option<&String>,
+        opt_place_desc: Option<&str>,
     ) -> Result<(), Diag<'infcx>> {
         let return_kind = match category {
             ConstraintCategory::Return(_) => "return",
@@ -3517,7 +3523,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     fn report_escaping_data(
         &self,
         borrow_span: Span,
-        name: &Option<String>,
+        name: Option<&str>,
         upvar_span: Span,
         upvar_name: Symbol,
         escape_span: Span,

compiler/rustc_borrowck/src/lib.rs

@@ -228,15 +228,15 @@ fn do_mir_borrowck<'tcx>(
 
     // Dump MIR results into a file, if that is enabled. This let us
     // write unit-tests, as well as helping with debugging.
-    nll::dump_nll_mir(&infcx, body, &regioncx, &opt_closure_req, &borrow_set);
+    nll::dump_nll_mir(&infcx, body, &regioncx, opt_closure_req.as_ref(), &borrow_set);
 
     // We also have a `#[rustc_regions]` annotation that causes us to dump
     // information.
     nll::dump_annotation(
         &infcx,
         body,
         &regioncx,
-        &opt_closure_req,
+        opt_closure_req.as_ref(),
         &opaque_type_values,
         &mut diags,
     );

compiler/rustc_borrowck/src/nll.rs

@@ -224,7 +224,7 @@ pub(super) fn dump_nll_mir<'tcx>(
     infcx: &BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
-    closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
+    closure_region_requirements: Option<&ClosureRegionRequirements<'tcx>>,
     borrow_set: &BorrowSet<'tcx>,
 ) {
     let tcx = infcx.tcx;
@@ -305,7 +305,7 @@ pub(super) fn dump_annotation<'tcx, 'infcx>(
     infcx: &'infcx BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
     regioncx: &RegionInferenceContext<'tcx>,
-    closure_region_requirements: &Option<ClosureRegionRequirements<'tcx>>,
+    closure_region_requirements: Option<&ClosureRegionRequirements<'tcx>>,
     opaque_type_values: &FxIndexMap<LocalDefId, OpaqueHiddenType<'tcx>>,
     diags: &mut crate::diags::BorrowckDiags<'infcx, 'tcx>,
 ) {

compiler/rustc_codegen_gcc/build_system/src/utils.rs

@@ -92,7 +92,7 @@ fn check_exit_status(
     Err(error)
 }
 
-fn command_error<D: Debug>(input: &[&dyn AsRef<OsStr>], cwd: &Option<&Path>, error: D) -> String {
+fn command_error<D: Debug>(input: &[&dyn AsRef<OsStr>], cwd: Option<&Path>, error: D) -> String {
     format!(
         "Command `{}`{} failed to run: {error:?}",
         input.iter().map(|s| s.as_ref().to_str().unwrap()).collect::<Vec<_>>().join(" "),

compiler/rustc_codegen_gcc/src/builder.rs

@@ -378,7 +378,7 @@ impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
                 gcc_func,
                 args.into(),
                 &func_name,
-                original_function_name,
+                original_function_name.map(String::as_str),
             )
         };
         let args_adjusted = args.len() != previous_arg_count;