don't destuct references just to reborrow

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -425,7 +425,7 @@ fn thin_lto(
         info!("going for that thin, thin LTO");
 
         let green_modules: FxHashMap<_, _> =
-            cached_modules.iter().map(|&(_, ref wp)| (wp.cgu_name.clone(), wp.clone())).collect();
+            cached_modules.iter().map(|(_, wp)| (wp.cgu_name.clone(), wp.clone())).collect();
 
         let full_scope_len = modules.len() + serialized_modules.len() + cached_modules.len();
         let mut thin_buffers = Vec::with_capacity(modules.len());

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -722,7 +722,7 @@ fn link_natively<'a>(
 
     linker::disable_localization(&mut cmd);
 
-    for &(ref k, ref v) in sess.target.link_env.as_ref() {
+    for (k, v) in sess.target.link_env.as_ref() {
         cmd.env(k.as_ref(), v.as_ref());
     }
     for k in sess.target.link_env_remove.as_ref() {

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -108,7 +108,7 @@ pub fn get_linker<'a>(
     if sess.target.is_like_msvc {
         if let Some(ref tool) = msvc_tool {
             cmd.args(tool.args());
-            for &(ref k, ref v) in tool.env() {
+            for (k, v) in tool.env() {
                 if k == "PATH" {
                     new_path.extend(env::split_paths(v));
                     msvc_changed_path = true;

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -332,7 +332,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     Immediate::new_slice(ptr, length.eval_usize(*self.tcx, self.param_env), self);
                 self.write_immediate(val, dest)
             }
-            (&ty::Dynamic(ref data_a, ..), &ty::Dynamic(ref data_b, ..)) => {
+            (ty::Dynamic(data_a, ..), ty::Dynamic(data_b, ..)) => {
                 let val = self.read_immediate(src)?;
                 if data_a.principal() == data_b.principal() {
                     // A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables.

compiler/rustc_expand/src/mbe/macro_check.rs

@@ -468,7 +468,7 @@ fn check_nested_occurrences(
                 // We check that the meta-variable is correctly used.
                 check_occurrences(sess, node_id, tt, macros, binders, ops, valid);
             }
-            (NestedMacroState::MacroName, &TokenTree::Delimited(_, ref del))
+            (NestedMacroState::MacroName, TokenTree::Delimited(_, del))
                 if del.delim == Delimiter::Parenthesis =>
             {
                 state = NestedMacroState::MacroNameParen;
@@ -483,7 +483,7 @@ fn check_nested_occurrences(
                     valid,
                 );
             }
-            (NestedMacroState::MacroNameParen, &TokenTree::Delimited(_, ref del))
+            (NestedMacroState::MacroNameParen, TokenTree::Delimited(_, del))
                 if del.delim == Delimiter::Brace =>
             {
                 state = NestedMacroState::Empty;

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -792,7 +792,7 @@ impl<'tt> FirstSets<'tt> {
                 TokenTree::Sequence(sp, ref seq_rep) => {
                     let subfirst_owned;
                     let subfirst = match self.first.get(&sp.entire()) {
-                        Some(&Some(ref subfirst)) => subfirst,
+                        Some(Some(subfirst)) => subfirst,
                         Some(&None) => {
                             subfirst_owned = self.first(&seq_rep.tts);
                             &subfirst_owned

compiler/rustc_hir_typeck/src/demand.rs

@@ -1275,7 +1275,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             };
 
         match (&expected_ty.kind(), &checked_ty.kind()) {
-            (&ty::Int(ref exp), &ty::Int(ref found)) => {
+            (ty::Int(exp), ty::Int(found)) => {
                 let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
                 {
                     (Some(exp), Some(found)) if exp < found => (true, false),
@@ -1288,7 +1288,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
                 true
             }
-            (&ty::Uint(ref exp), &ty::Uint(ref found)) => {
+            (ty::Uint(exp), ty::Uint(found)) => {
                 let (f2e_is_fallible, e2f_is_fallible) = match (exp.bit_width(), found.bit_width())
                 {
                     (Some(exp), Some(found)) if exp < found => (true, false),
@@ -1321,7 +1321,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 suggest_to_change_suffix_or_into(err, f2e_is_fallible, e2f_is_fallible);
                 true
             }
-            (&ty::Float(ref exp), &ty::Float(ref found)) => {
+            (ty::Float(exp), ty::Float(found)) => {
                 if found.bit_width() < exp.bit_width() {
                     suggest_to_change_suffix_or_into(err, false, true);
                 } else if literal_is_ty_suffixed(expr) {
@@ -1357,7 +1357,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
                 true
             }
-            (&ty::Float(ref exp), &ty::Uint(ref found)) => {
+            (ty::Float(exp), ty::Uint(found)) => {
                 // if `found` is `None` (meaning found is `usize`), don't suggest `.into()`
                 if exp.bit_width() > found.bit_width().unwrap_or(256) {
                     err.multipart_suggestion_verbose(
@@ -1386,7 +1386,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
                 true
             }
-            (&ty::Float(ref exp), &ty::Int(ref found)) => {
+            (ty::Float(exp), ty::Int(found)) => {
                 // if `found` is `None` (meaning found is `isize`), don't suggest `.into()`
                 if exp.bit_width() > found.bit_width().unwrap_or(256) {
                     err.multipart_suggestion_verbose(

compiler/rustc_hir_typeck/src/expr.rs

@@ -1874,7 +1874,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // I don't use 'is_range_literal' because only double-sided, half-open ranges count.
         if let ExprKind::Struct(
                 QPath::LangItem(LangItem::Range, ..),
-                &[ref range_start, ref range_end],
+                [range_start, range_end],
                 _,
             ) = last_expr_field.expr.kind
             && let variant_field =

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -754,7 +754,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     return true
                 }
             }
-            &hir::FnRetTy::Return(ref ty) => {
+            hir::FnRetTy::Return(ty) => {
                 // Only point to return type if the expected type is the return type, as if they
                 // are not, the expectation must have been caused by something else.
                 debug!("suggest_missing_return_type: return type {:?} node {:?}", ty, ty.kind);

compiler/rustc_incremental/src/assert_dep_graph.rs

@@ -249,7 +249,7 @@ fn dump_graph(query: &DepGraphQuery) {
         // dump a .txt file with just the edges:
         let txt_path = format!("{}.txt", path);
         let mut file = BufWriter::new(File::create(&txt_path).unwrap());
-        for &(ref source, ref target) in &edges {
+        for (source, target) in &edges {
             write!(file, "{:?} -> {:?}\n", source, target).unwrap();
         }
     }

compiler/rustc_infer/src/traits/project.rs

@@ -200,7 +200,7 @@ impl<'tcx> ProjectionCache<'_, 'tcx> {
     pub fn complete(&mut self, key: ProjectionCacheKey<'tcx>, result: EvaluationResult) {
         let mut map = self.map();
         match map.get(&key) {
-            Some(&ProjectionCacheEntry::NormalizedTy { ref ty, complete: _ }) => {
+            Some(ProjectionCacheEntry::NormalizedTy { ty, complete: _ }) => {
                 info!("ProjectionCacheEntry::complete({:?}) - completing {:?}", key, ty);
                 let mut ty = ty.clone();
                 if result.must_apply_considering_regions() {

compiler/rustc_lint/src/context.rs

@@ -438,18 +438,18 @@ impl LintStore {
                         return CheckLintNameResult::Tool(Ok(&lint_ids));
                     }
                 },
-                Some(&Id(ref id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
+                Some(Id(id)) => return CheckLintNameResult::Tool(Ok(slice::from_ref(id))),
                 // If the lint was registered as removed or renamed by the lint tool, we don't need
                 // to treat tool_lints and rustc lints different and can use the code below.
                 _ => {}
             }
         }
         match self.by_name.get(&complete_name) {
-            Some(&Renamed(ref new_name, _)) => CheckLintNameResult::Warning(
+            Some(Renamed(new_name, _)) => CheckLintNameResult::Warning(
                 format!("lint `{}` has been renamed to `{}`", complete_name, new_name),
                 Some(new_name.to_owned()),
             ),
-            Some(&Removed(ref reason)) => CheckLintNameResult::Warning(
+            Some(Removed(reason)) => CheckLintNameResult::Warning(
                 format!("lint `{}` has been removed: {}", complete_name, reason),
                 None,
             ),
@@ -470,7 +470,7 @@ impl LintStore {
                     CheckLintNameResult::Ok(&lint_ids)
                 }
             },
-            Some(&Id(ref id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
+            Some(Id(id)) => CheckLintNameResult::Ok(slice::from_ref(id)),
             Some(&Ignored) => CheckLintNameResult::Ok(&[]),
         }
     }
@@ -513,7 +513,7 @@ impl LintStore {
                     CheckLintNameResult::Tool(Err((Some(&lint_ids), complete_name)))
                 }
             },
-            Some(&Id(ref id)) => {
+            Some(Id(id)) => {
                 CheckLintNameResult::Tool(Err((Some(slice::from_ref(id)), complete_name)))
             }
             Some(other) => {

compiler/rustc_lint/src/unused.rs

@@ -1279,7 +1279,7 @@ impl UnusedImportBraces {
     fn check_use_tree(&self, cx: &EarlyContext<'_>, use_tree: &ast::UseTree, item: &ast::Item) {
         if let ast::UseTreeKind::Nested(ref items) = use_tree.kind {
             // Recursively check nested UseTrees
-            for &(ref tree, _) in items {
+            for (tree, _) in items {
                 self.check_use_tree(cx, tree, item);
             }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1849,7 +1849,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         // the assumption that they are numbered 1 to n.
         // FIXME (#2166): This is not nearly enough to support correct versioning
         // but is enough to get transitive crate dependencies working.
-        self.lazy_array(deps.iter().map(|&(_, ref dep)| dep))
+        self.lazy_array(deps.iter().map(|(_, dep)| dep))
     }
 
     fn encode_lib_features(&mut self) -> LazyArray<(Symbol, Option<Symbol>)> {
@@ -1986,7 +1986,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         self.lazy_array(
             exported_symbols
                 .iter()
-                .filter(|&&(ref exported_symbol, _)| match *exported_symbol {
+                .filter(|&(exported_symbol, _)| match *exported_symbol {
                     ExportedSymbol::NoDefId(symbol_name) => symbol_name != metadata_symbol_name,
                     _ => true,
                 })

compiler/rustc_middle/src/mir/tcx.rs

@@ -235,7 +235,7 @@ impl<'tcx> Operand<'tcx> {
     {
         match self {
             &Operand::Copy(ref l) | &Operand::Move(ref l) => l.ty(local_decls, tcx).ty,
-            &Operand::Constant(ref c) => c.literal.ty(),
+            Operand::Constant(c) => c.literal.ty(),
         }
     }
 }

compiler/rustc_middle/src/ty/flags.rs

@@ -95,7 +95,7 @@ impl FlagComputation {
                 self.add_flags(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
             }
 
-            &ty::Generator(_, ref substs, _) => {
+            ty::Generator(_, substs, _) => {
                 let substs = substs.as_generator();
                 let should_remove_further_specializable =
                     !self.flags.contains(TypeFlags::STILL_FURTHER_SPECIALIZABLE);
@@ -186,7 +186,7 @@ impl FlagComputation {
 
             &ty::Slice(tt) => self.add_ty(tt),
 
-            &ty::RawPtr(ref m) => {
+            ty::RawPtr(m) => {
                 self.add_ty(m.ty);
             }
 

compiler/rustc_middle/src/ty/relate.rs

@@ -428,7 +428,7 @@ pub fn super_relate_tys<'tcx, R: TypeRelation<'tcx>>(
             Ok(a)
         }
 
-        (&ty::Param(ref a_p), &ty::Param(ref b_p)) if a_p.index == b_p.index => Ok(a),
+        (ty::Param(a_p), ty::Param(b_p)) if a_p.index == b_p.index => Ok(a),
 
         (ty::Placeholder(p1), ty::Placeholder(p2)) if p1 == p2 => Ok(a),
 

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -551,16 +551,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             //
             // FIXME(#29623) we could use PatKind::Range to rule
             // things out here, in some cases.
-            (
-                &TestKind::SwitchInt { switch_ty: _, ref options },
-                &PatKind::Constant { ref value },
-            ) if is_switch_ty(match_pair.pattern.ty) => {
+            (TestKind::SwitchInt { switch_ty: _, options }, PatKind::Constant { value })
+                if is_switch_ty(match_pair.pattern.ty) =>
+            {
                 let index = options.get_index_of(value).unwrap();
                 self.candidate_without_match_pair(match_pair_index, candidate);
                 Some(index)
             }
 
-            (&TestKind::SwitchInt { switch_ty: _, ref options }, &PatKind::Range(ref range)) => {
+            (TestKind::SwitchInt { switch_ty: _, options }, PatKind::Range(range)) => {
                 let not_contained =
                     self.values_not_contained_in_range(&*range, options).unwrap_or(false);
 
@@ -578,7 +577,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             (
                 &TestKind::Len { len: test_len, op: BinOp::Eq },
-                &PatKind::Slice { ref prefix, ref slice, ref suffix },
+                PatKind::Slice { prefix, slice, suffix },
             ) => {
                 let pat_len = (prefix.len() + suffix.len()) as u64;
                 match (test_len.cmp(&pat_len), slice) {
@@ -615,7 +614,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             (
                 &TestKind::Len { len: test_len, op: BinOp::Ge },
-                &PatKind::Slice { ref prefix, ref slice, ref suffix },
+                PatKind::Slice { prefix, slice, suffix },
             ) => {
                 // the test is `$actual_len >= test_len`
                 let pat_len = (prefix.len() + suffix.len()) as u64;
@@ -651,7 +650,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 }
             }
 
-            (&TestKind::Range(ref test), &PatKind::Range(ref pat)) => {
+            (TestKind::Range(test), PatKind::Range(pat)) => {
                 use std::cmp::Ordering::*;
 
                 if test == pat {
@@ -678,7 +677,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 no_overlap
             }
 
-            (&TestKind::Range(ref range), &PatKind::Constant { value }) => {
+            (TestKind::Range(range), &PatKind::Constant { value }) => {
                 if let Some(false) = self.const_range_contains(&*range, value) {
                     // `value` is not contained in the testing range,
                     // so `value` can be matched only if this test fails.

compiler/rustc_passes/src/hir_stats.rs

@@ -121,7 +121,7 @@ impl<'k> StatCollector<'k> {
 
     fn print(&self, title: &str, prefix: &str) {
         let mut nodes: Vec<_> = self.nodes.iter().collect();
-        nodes.sort_by_key(|&(_, ref node)| node.stats.count * node.stats.size);
+        nodes.sort_by_key(|(_, node)| node.stats.count * node.stats.size);
 
         let total_size = nodes.iter().map(|(_, node)| node.stats.count * node.stats.size).sum();
 
@@ -147,7 +147,7 @@ impl<'k> StatCollector<'k> {
             );
             if !node.subnodes.is_empty() {
                 let mut subnodes: Vec<_> = node.subnodes.iter().collect();
-                subnodes.sort_by_key(|&(_, ref subnode)| subnode.count * subnode.size);
+                subnodes.sort_by_key(|(_, subnode)| subnode.count * subnode.size);
 
                 for (label, subnode) in subnodes {
                     let size = subnode.count * subnode.size;

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -576,7 +576,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                 // Ensure there is at most one `self` in the list
                 let self_spans = items
                     .iter()
-                    .filter_map(|&(ref use_tree, _)| {
+                    .filter_map(|(use_tree, _)| {
                         if let ast::UseTreeKind::Simple(..) = use_tree.kind {
                             if use_tree.ident().name == kw::SelfLower {
                                 return Some(use_tree.span);

compiler/rustc_session/src/session.rs

@@ -1323,7 +1323,7 @@ pub fn build_session(
     let warnings_allow = sopts
         .lint_opts
         .iter()
-        .rfind(|&&(ref key, _)| *key == "warnings")
+        .rfind(|&(key, _)| *key == "warnings")
         .map_or(false, |&(_, level)| level == lint::Allow);
     let cap_lints_allow = sopts.lint_cap.map_or(false, |cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -226,7 +226,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
             let arg_length = arguments.len();
             let distinct = matches!(other, &[ArgKind::Tuple(..)]);
             match (arg_length, arguments.get(0)) {
-                (1, Some(&ArgKind::Tuple(_, ref fields))) => {
+                (1, Some(ArgKind::Tuple(_, fields))) => {
                     format!("a single {}-tuple as argument", fields.len())
                 }
                 _ => format!(