Rollup merge of #127729 - compiler-errors:ed-2024-gen, r=oli-obk

Stop using the `gen` identifier in the compiler

In preparation for edition 2024, this PR previews the fallout of removing usages of `gen` since it's being reserved as a keyword.

There are two notable changes here:
1. Had to rename `fn gen(..)` in gen/kill analysis to `gen_`. Not certain there's a better name than that.
2. There are (false?[^1]) positives in `rustc_macros` when using synstructure, which uses `gen impl` to mark an implementation. We could suppress this in a one-off way, or perhaps just ignore `gen` in macros altogether, since if an identifier ends up in expanded code then it'll get properly denied anyways.

Not relevant to the compiler, but it's gonna be really annoying to change `rand`'s `gen` fn in the library and miri...

[^1]: I haven't looked at the synstructure proc macro code itself so I'm not certain if it'll start to fail when converted to ed2024 (or, e.g., when syn starts parsing `gen` as a kw).

17 files changed, 79 insertions, 68 deletions

diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 00a30dc2240..59b3c6916cb 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -553,7 +553,7 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, '_, 'tcx> {
                         panic!("could not find BorrowIndex for location {location:?}");
                     });
 
-                    trans.gen(index);
+                    trans.gen_(index);
                 }
 
                 // Make sure there are no remaining borrows for variables
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 4561f9d9b49..3bd7b300758 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -3218,10 +3218,10 @@ impl<'hir> Item<'hir> {
             ItemKind::Static(ty, mutbl, body), (ty, *mutbl, *body);
 
         expect_const, (&'hir Ty<'hir>, &'hir Generics<'hir>, BodyId),
-            ItemKind::Const(ty, gen, body), (ty, gen, *body);
+            ItemKind::Const(ty, generics, body), (ty, generics, *body);
 
         expect_fn, (&FnSig<'hir>, &'hir Generics<'hir>, BodyId),
-            ItemKind::Fn(sig, gen, body), (sig, gen, *body);
+            ItemKind::Fn(sig, generics, body), (sig, generics, *body);
 
         expect_macro, (&ast::MacroDef, MacroKind), ItemKind::Macro(def, mk), (def, *mk);
 
@@ -3233,25 +3233,25 @@ impl<'hir> Item<'hir> {
         expect_global_asm, &'hir InlineAsm<'hir>, ItemKind::GlobalAsm(asm), asm;
 
         expect_ty_alias, (&'hir Ty<'hir>, &'hir Generics<'hir>),
-            ItemKind::TyAlias(ty, gen), (ty, gen);
+            ItemKind::TyAlias(ty, generics), (ty, generics);
 
         expect_opaque_ty, &OpaqueTy<'hir>, ItemKind::OpaqueTy(ty), ty;
 
-        expect_enum, (&EnumDef<'hir>, &'hir Generics<'hir>), ItemKind::Enum(def, gen), (def, gen);
+        expect_enum, (&EnumDef<'hir>, &'hir Generics<'hir>), ItemKind::Enum(def, generics), (def, generics);
 
         expect_struct, (&VariantData<'hir>, &'hir Generics<'hir>),
-            ItemKind::Struct(data, gen), (data, gen);
+            ItemKind::Struct(data, generics), (data, generics);
 
         expect_union, (&VariantData<'hir>, &'hir Generics<'hir>),
-            ItemKind::Union(data, gen), (data, gen);
+            ItemKind::Union(data, generics), (data, generics);
 
         expect_trait,
             (IsAuto, Safety, &'hir Generics<'hir>, GenericBounds<'hir>, &'hir [TraitItemRef]),
-            ItemKind::Trait(is_auto, safety, gen, bounds, items),
-            (*is_auto, *safety, gen, bounds, items);
+            ItemKind::Trait(is_auto, safety, generics, bounds, items),
+            (*is_auto, *safety, generics, bounds, items);
 
         expect_trait_alias, (&'hir Generics<'hir>, GenericBounds<'hir>),
-            ItemKind::TraitAlias(gen, bounds), (gen, bounds);
+            ItemKind::TraitAlias(generics, bounds), (generics, bounds);
 
         expect_impl, &'hir Impl<'hir>, ItemKind::Impl(imp), imp;
     }
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index ab0f356ce91..9c588091239 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -2554,7 +2554,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         .and_then(|node| node.generics())
                         .into_iter()
                         .flat_map(|generics| generics.params)
-                        .find(|gen| &gen.def_id.to_def_id() == res_def_id)
+                        .find(|param| &param.def_id.to_def_id() == res_def_id)
                 } else {
                     None
                 }
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
index a3abbdcf18c..2743660ab89 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
@@ -71,6 +71,8 @@ impl<'a> DiagnosticDerive<'a> {
         });
 
         // A lifetime of `'a` causes conflicts, but `_sess` is fine.
+        // FIXME(edition_2024): Fix the `keyword_idents_2024` lint to not trigger here?
+        #[allow(keyword_idents_2024)]
         let mut imp = structure.gen_impl(quote! {
             gen impl<'_sess, G> rustc_errors::Diagnostic<'_sess, G> for @Self
                 where G: rustc_errors::EmissionGuarantee
@@ -148,6 +150,8 @@ impl<'a> LintDiagnosticDerive<'a> {
             }
         });
 
+        // FIXME(edition_2024): Fix the `keyword_idents_2024` lint to not trigger here?
+        #[allow(keyword_idents_2024)]
         let mut imp = structure.gen_impl(quote! {
             gen impl<'__a> rustc_errors::LintDiagnostic<'__a, ()> for @Self {
                 #[track_caller]
diff --git a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
index 69014f39925..7f090f5ebc1 100644
--- a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
@@ -86,6 +86,9 @@ impl SubdiagnosticDerive {
 
         let diag = &self.diag;
         let f = &self.f;
+
+        // FIXME(edition_2024): Fix the `keyword_idents_2024` lint to not trigger here?
+        #[allow(keyword_idents_2024)]
         let ret = structure.gen_impl(quote! {
             gen impl rustc_errors::Subdiagnostic for @Self {
                 fn add_to_diag_with<__G, __F>(
@@ -100,6 +103,7 @@ impl SubdiagnosticDerive {
                 }
             }
         });
+
         ret
     }
 }
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index 0d3c419748b..0031ded2440 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -1016,14 +1016,14 @@ macro_rules! extra_body_methods {
 macro_rules! super_body {
     ($self:ident, $body:ident, $($mutability:ident, $invalidate:tt)?) => {
         let span = $body.span;
-        if let Some(gen) = &$($mutability)? $body.coroutine {
-            if let Some(yield_ty) = $(& $mutability)? gen.yield_ty {
+        if let Some(coroutine) = &$($mutability)? $body.coroutine {
+            if let Some(yield_ty) = $(& $mutability)? coroutine.yield_ty {
                 $self.visit_ty(
                     yield_ty,
                     TyContext::YieldTy(SourceInfo::outermost(span))
                 );
             }
-            if let Some(resume_ty) = $(& $mutability)? gen.resume_ty {
+            if let Some(resume_ty) = $(& $mutability)? coroutine.resume_ty {
                 $self.visit_ty(
                     resume_ty,
                     TyContext::ResumeTy(SourceInfo::outermost(span))
diff --git a/compiler/rustc_mir_dataflow/src/framework/mod.rs b/compiler/rustc_mir_dataflow/src/framework/mod.rs
index 09cdb055a3e..6eaed0f7753 100644
--- a/compiler/rustc_mir_dataflow/src/framework/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/mod.rs
@@ -402,7 +402,7 @@ where
 /// building up a `GenKillSet` and then throwing it away.
 pub trait GenKill<T> {
     /// Inserts `elem` into the state vector.
-    fn gen(&mut self, elem: T);
+    fn gen_(&mut self, elem: T);
 
     /// Removes `elem` from the state vector.
     fn kill(&mut self, elem: T);
@@ -410,7 +410,7 @@ pub trait GenKill<T> {
     /// Calls `gen` for each element in `elems`.
     fn gen_all(&mut self, elems: impl IntoIterator<Item = T>) {
         for elem in elems {
-            self.gen(elem);
+            self.gen_(elem);
         }
     }
 
@@ -424,12 +424,12 @@ pub trait GenKill<T> {
 
 /// Stores a transfer function for a gen/kill problem.
 ///
-/// Calling `gen`/`kill` on a `GenKillSet` will "build up" a transfer function so that it can be
-/// applied multiple times efficiently. When there are multiple calls to `gen` and/or `kill` for
+/// Calling `gen_`/`kill` on a `GenKillSet` will "build up" a transfer function so that it can be
+/// applied multiple times efficiently. When there are multiple calls to `gen_` and/or `kill` for
 /// the same element, the most recent one takes precedence.
 #[derive(Clone)]
 pub struct GenKillSet<T> {
-    gen: HybridBitSet<T>,
+    gen_: HybridBitSet<T>,
     kill: HybridBitSet<T>,
 }
 
@@ -437,31 +437,31 @@ impl<T: Idx> GenKillSet<T> {
     /// Creates a new transfer function that will leave the dataflow state unchanged.
     pub fn identity(universe: usize) -> Self {
         GenKillSet {
-            gen: HybridBitSet::new_empty(universe),
+            gen_: HybridBitSet::new_empty(universe),
             kill: HybridBitSet::new_empty(universe),
         }
     }
 
     pub fn apply(&self, state: &mut impl BitSetExt<T>) {
-        state.union(&self.gen);
+        state.union(&self.gen_);
         state.subtract(&self.kill);
     }
 }
 
 impl<T: Idx> GenKill<T> for GenKillSet<T> {
-    fn gen(&mut self, elem: T) {
-        self.gen.insert(elem);
+    fn gen_(&mut self, elem: T) {
+        self.gen_.insert(elem);
         self.kill.remove(elem);
     }
 
     fn kill(&mut self, elem: T) {
         self.kill.insert(elem);
-        self.gen.remove(elem);
+        self.gen_.remove(elem);
     }
 }
 
 impl<T: Idx> GenKill<T> for BitSet<T> {
-    fn gen(&mut self, elem: T) {
+    fn gen_(&mut self, elem: T) {
         self.insert(elem);
     }
 
@@ -471,7 +471,7 @@ impl<T: Idx> GenKill<T> for BitSet<T> {
 }
 
 impl<T: Idx> GenKill<T> for ChunkedBitSet<T> {
-    fn gen(&mut self, elem: T) {
+    fn gen_(&mut self, elem: T) {
         self.insert(elem);
     }
 
@@ -481,11 +481,11 @@ impl<T: Idx> GenKill<T> for ChunkedBitSet<T> {
 }
 
 impl<T, S: GenKill<T>> GenKill<T> for MaybeReachable<S> {
-    fn gen(&mut self, elem: T) {
+    fn gen_(&mut self, elem: T) {
         match self {
             // If the state is not reachable, adding an element does nothing.
             MaybeReachable::Unreachable => {}
-            MaybeReachable::Reachable(set) => set.gen(elem),
+            MaybeReachable::Reachable(set) => set.gen_(elem),
         }
     }
 
@@ -499,7 +499,7 @@ impl<T, S: GenKill<T>> GenKill<T> for MaybeReachable<S> {
 }
 
 impl<T: Idx> GenKill<T> for lattice::Dual<BitSet<T>> {
-    fn gen(&mut self, elem: T) {
+    fn gen_(&mut self, elem: T) {
         self.0.insert(elem);
     }
 
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 574da949b0e..885fdd0d58b 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -97,7 +97,7 @@ where
             Rvalue::AddressOf(_, borrowed_place)
             | Rvalue::Ref(_, BorrowKind::Mut { .. } | BorrowKind::Shared, borrowed_place) => {
                 if !borrowed_place.is_indirect() {
-                    self.trans.gen(borrowed_place.local);
+                    self.trans.gen_(borrowed_place.local);
                 }
             }
 
@@ -131,7 +131,7 @@ where
                 //
                 // [#61069]: https://github.com/rust-lang/rust/pull/61069
                 if !dropped_place.is_indirect() {
-                    self.trans.gen(dropped_place.local);
+                    self.trans.gen_(dropped_place.local);
                 }
             }
 
@@ -159,8 +159,8 @@ pub fn borrowed_locals(body: &Body<'_>) -> BitSet<Local> {
 
     impl GenKill<Local> for Borrowed {
         #[inline]
-        fn gen(&mut self, elem: Local) {
-            self.0.gen(elem)
+        fn gen_(&mut self, elem: Local) {
+            self.0.gen_(elem)
         }
         #[inline]
         fn kill(&mut self, _: Local) {
diff --git a/compiler/rustc_mir_dataflow/src/impls/initialized.rs b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
index ffcf630b653..a9bceeccdce 100644
--- a/compiler/rustc_mir_dataflow/src/impls/initialized.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
@@ -283,7 +283,7 @@ impl<'a, 'mir, 'tcx> MaybeInitializedPlaces<'a, 'mir, 'tcx> {
     ) {
         match state {
             DropFlagState::Absent => trans.kill(path),
-            DropFlagState::Present => trans.gen(path),
+            DropFlagState::Present => trans.gen_(path),
         }
     }
 }
@@ -295,7 +295,7 @@ impl<'a, 'tcx> MaybeUninitializedPlaces<'a, '_, 'tcx> {
         state: DropFlagState,
     ) {
         match state {
-            DropFlagState::Absent => trans.gen(path),
+            DropFlagState::Absent => trans.gen_(path),
             DropFlagState::Present => trans.kill(path),
         }
     }
@@ -309,7 +309,7 @@ impl<'a, 'tcx> DefinitelyInitializedPlaces<'a, 'tcx> {
     ) {
         match state {
             DropFlagState::Absent => trans.kill(path),
-            DropFlagState::Present => trans.gen(path),
+            DropFlagState::Present => trans.gen_(path),
         }
     }
 }
@@ -331,7 +331,7 @@ impl<'tcx> AnalysisDomain<'tcx> for MaybeInitializedPlaces<'_, '_, 'tcx> {
             MaybeReachable::Reachable(ChunkedBitSet::new_empty(self.move_data().move_paths.len()));
         drop_flag_effects_for_function_entry(self.body, self.mdpe, |path, s| {
             assert!(s == DropFlagState::Present);
-            state.gen(path);
+            state.gen_(path);
         });
     }
 }
@@ -362,7 +362,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, '_, 'tcx> {
             && let LookupResult::Exact(mpi) = self.move_data().rev_lookup.find(place.as_ref())
         {
             on_all_children_bits(self.move_data(), mpi, |child| {
-                trans.gen(child);
+                trans.gen_(child);
             })
         }
     }
@@ -400,7 +400,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, '_, 'tcx> {
                 self.move_data(),
                 self.move_data().rev_lookup.find(place.as_ref()),
                 |mpi| {
-                    trans.gen(mpi);
+                    trans.gen_(mpi);
                 },
             );
         });
@@ -572,7 +572,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, '_, 'tcx> {
                 self.move_data(),
                 enum_place,
                 variant,
-                |mpi| trans.gen(mpi),
+                |mpi| trans.gen_(mpi),
             );
         });
     }
@@ -643,7 +643,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for DefinitelyInitializedPlaces<'_, 'tcx> {
                 self.move_data(),
                 self.move_data().rev_lookup.find(place.as_ref()),
                 |mpi| {
-                    trans.gen(mpi);
+                    trans.gen_(mpi);
                 },
             );
         });
@@ -738,7 +738,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, '_, 'tcx> {
 
         let call_loc = self.body.terminator_loc(block);
         for init_index in &init_loc_map[call_loc] {
-            trans.gen(*init_index);
+            trans.gen_(*init_index);
         }
     }
 }
diff --git a/compiler/rustc_mir_dataflow/src/impls/liveness.rs b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
index 334fa9976f0..48bdb131601 100644
--- a/compiler/rustc_mir_dataflow/src/impls/liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
@@ -116,7 +116,7 @@ where
                     self.0.kill(place.local);
                 }
             }
-            Some(DefUse::Use) => self.0.gen(place.local),
+            Some(DefUse::Use) => self.0.gen_(place.local),
             None => {}
         }
 
@@ -154,7 +154,7 @@ impl DefUse {
     fn apply(trans: &mut impl GenKill<Local>, place: Place<'_>, context: PlaceContext) {
         match DefUse::for_place(place, context) {
             Some(DefUse::Def) => trans.kill(place.local),
-            Some(DefUse::Use) => trans.gen(place.local),
+            Some(DefUse::Use) => trans.gen_(place.local),
             None => {}
         }
     }
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index f850a710277..682cec12f1f 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -54,7 +54,7 @@ impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageLive<'a> {
         _: Location,
     ) {
         match stmt.kind {
-            StatementKind::StorageLive(l) => trans.gen(l),
+            StatementKind::StorageLive(l) => trans.gen_(l),
             StatementKind::StorageDead(l) => trans.kill(l),
             _ => (),
         }
@@ -127,7 +127,7 @@ impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageDead<'a> {
     ) {
         match stmt.kind {
             StatementKind::StorageLive(l) => trans.kill(l),
-            StatementKind::StorageDead(l) => trans.gen(l),
+            StatementKind::StorageDead(l) => trans.gen_(l),
             _ => (),
         }
     }
@@ -208,7 +208,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
             StatementKind::Assign(box (place, _))
             | StatementKind::SetDiscriminant { box place, .. }
             | StatementKind::Deinit(box place) => {
-                trans.gen(place.local);
+                trans.gen_(place.local);
             }
 
             // Nothing to do for these. Match exhaustively so this fails to compile when new
@@ -250,7 +250,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
 
         match &terminator.kind {
             TerminatorKind::Call { destination, .. } => {
-                trans.gen(destination.local);
+                trans.gen_(destination.local);
             }
 
             // Note that we do *not* gen the `resume_arg` of `Yield` terminators. The reason for
@@ -265,7 +265,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
                         InlineAsmOperand::Out { place, .. }
                         | InlineAsmOperand::InOut { out_place: place, .. } => {
                             if let Some(place) = place {
-                                trans.gen(place.local);
+                                trans.gen_(place.local);
                             }
                         }
                         InlineAsmOperand::In { .. }
@@ -341,7 +341,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
         _block: BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
-        return_places.for_each(|place| trans.gen(place.local));
+        return_places.for_each(|place| trans.gen_(place.local));
     }
 }
 
diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs
index aeb34743608..f033905e9f6 100644
--- a/src/bootstrap/src/core/builder.rs
+++ b/src/bootstrap/src/core/builder.rs
@@ -1998,6 +1998,9 @@ impl<'a> Builder<'a> {
         if mode == Mode::Rustc {
             rustflags.arg("-Zunstable-options");
             rustflags.arg("-Wrustc::internal");
+            // FIXME(edition_2024): Change this to `-Wrust_2024_idioms` when all
+            // of the individual lints are satisfied.
+            rustflags.arg("-Wkeyword_idents_2024");
         }
 
         if self.config.rust_frame_pointers {
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 98ce268a774..a0e28d2f55c 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1052,12 +1052,12 @@ fn clean_fn_decl_legacy_const_generics(func: &mut Function, attrs: &[ast::Attrib
         for (pos, literal) in meta_item_list.iter().filter_map(|meta| meta.lit()).enumerate() {
             match literal.kind {
                 ast::LitKind::Int(a, _) => {
-                    let gen = func.generics.params.remove(0);
+                    let param = func.generics.params.remove(0);
                     if let GenericParamDef {
                         name,
                         kind: GenericParamDefKind::Const { ty, .. },
                         ..
-                    } = gen
+                    } = param
                     {
                         func.decl
                             .inputs
diff --git a/src/librustdoc/html/render/search_index.rs b/src/librustdoc/html/render/search_index.rs
index bc8bdffc331..66d3f0fd8ce 100644
--- a/src/librustdoc/html/render/search_index.rs
+++ b/src/librustdoc/html/render/search_index.rs
@@ -1051,7 +1051,7 @@ fn simplify_fn_type<'tcx, 'a>(
         let mut ty_generics = Vec::new();
         let mut ty_constraints = Vec::new();
         if let Some(arg_generics) = arg.generic_args() {
-            for ty in arg_generics.into_iter().filter_map(|gen| match gen {
+            for ty in arg_generics.into_iter().filter_map(|param| match param {
                 clean::GenericArg::Type(ty) => Some(ty),
                 _ => None,
             }) {
@@ -1172,8 +1172,8 @@ fn simplify_fn_constraint<'tcx, 'a>(
 ) {
     let mut ty_constraints = Vec::new();
     let ty_constrained_assoc = RenderTypeId::AssociatedType(constraint.assoc.name);
-    for gen in &constraint.assoc.args {
-        match gen {
+    for param in &constraint.assoc.args {
+        match param {
             clean::GenericArg::Type(arg) => simplify_fn_type(
                 self_,
                 generics,
diff --git a/src/tools/clippy/clippy_lints/src/misc_early/mod.rs b/src/tools/clippy/clippy_lints/src/misc_early/mod.rs
index fedcfd11fdc..4cba13a05c2 100644
--- a/src/tools/clippy/clippy_lints/src/misc_early/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/misc_early/mod.rs
@@ -364,8 +364,8 @@ declare_lint_pass!(MiscEarlyLints => [
 ]);
 
 impl EarlyLintPass for MiscEarlyLints {
-    fn check_generics(&mut self, cx: &EarlyContext<'_>, gen: &Generics) {
-        for param in &gen.params {
+    fn check_generics(&mut self, cx: &EarlyContext<'_>, generics: &Generics) {
+        for param in &generics.params {
             builtin_type_shadow::check(cx, param);
         }
     }
diff --git a/src/tools/clippy/clippy_lints/src/trait_bounds.rs b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
index c05cd9ed593..07390d6f430 100644
--- a/src/tools/clippy/clippy_lints/src/trait_bounds.rs
+++ b/src/tools/clippy/clippy_lints/src/trait_bounds.rs
@@ -102,9 +102,9 @@ impl TraitBounds {
 impl_lint_pass!(TraitBounds => [TYPE_REPETITION_IN_BOUNDS, TRAIT_DUPLICATION_IN_BOUNDS]);
 
 impl<'tcx> LateLintPass<'tcx> for TraitBounds {
-    fn check_generics(&mut self, cx: &LateContext<'tcx>, gen: &'tcx Generics<'_>) {
-        self.check_type_repetition(cx, gen);
-        check_trait_bound_duplication(cx, gen);
+    fn check_generics(&mut self, cx: &LateContext<'tcx>, generics: &'tcx Generics<'_>) {
+        self.check_type_repetition(cx, generics);
+        check_trait_bound_duplication(cx, generics);
     }
 
     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'tcx>) {
@@ -238,7 +238,7 @@ impl TraitBounds {
     }
 
     #[allow(clippy::mutable_key_type)]
-    fn check_type_repetition<'tcx>(&self, cx: &LateContext<'tcx>, gen: &'tcx Generics<'_>) {
+    fn check_type_repetition<'tcx>(&self, cx: &LateContext<'tcx>, generics: &'tcx Generics<'_>) {
         struct SpanlessTy<'cx, 'tcx> {
             ty: &'tcx Ty<'tcx>,
             cx: &'cx LateContext<'tcx>,
@@ -258,12 +258,12 @@ impl TraitBounds {
         }
         impl Eq for SpanlessTy<'_, '_> {}
 
-        if gen.span.from_expansion() {
+        if generics.span.from_expansion() {
             return;
         }
         let mut map: UnhashMap<SpanlessTy<'_, '_>, Vec<&GenericBound<'_>>> = UnhashMap::default();
         let mut applicability = Applicability::MaybeIncorrect;
-        for bound in gen.predicates {
+        for bound in generics.predicates {
             if let WherePredicate::BoundPredicate(ref p) = bound
                 && p.origin != PredicateOrigin::ImplTrait
                 && p.bounds.len() as u64 <= self.max_trait_bounds
@@ -301,8 +301,8 @@ impl TraitBounds {
     }
 }
 
-fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
-    if gen.span.from_expansion() {
+fn check_trait_bound_duplication(cx: &LateContext<'_>, generics: &'_ Generics<'_>) {
+    if generics.span.from_expansion() {
         return;
     }
 
@@ -313,7 +313,7 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
     //       |
     // collects each of these where clauses into a set keyed by generic name and comparable trait
     // eg. (T, Clone)
-    let where_predicates = gen
+    let where_predicates = generics
         .predicates
         .iter()
         .filter_map(|pred| {
@@ -342,7 +342,7 @@ fn check_trait_bound_duplication(cx: &LateContext<'_>, gen: &'_ Generics<'_>) {
     //            |
     // compare trait bounds keyed by generic name and comparable trait to collected where
     // predicates eg. (T, Clone)
-    for predicate in gen.predicates.iter().filter(|pred| !pred.in_where_clause()) {
+    for predicate in generics.predicates.iter().filter(|pred| !pred.in_where_clause()) {
         if let WherePredicate::BoundPredicate(bound_predicate) = predicate
             && bound_predicate.origin != PredicateOrigin::ImplTrait
             && !bound_predicate.span.from_expansion()
diff --git a/src/tools/clippy/clippy_lints/src/types/type_complexity.rs b/src/tools/clippy/clippy_lints/src/types/type_complexity.rs
index 0aa50c99c16..b6e765d7c39 100644
--- a/src/tools/clippy/clippy_lints/src/types/type_complexity.rs
+++ b/src/tools/clippy/clippy_lints/src/types/type_complexity.rs
@@ -57,7 +57,7 @@ impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
                     bound
                         .bound_generic_params
                         .iter()
-                        .any(|gen| matches!(gen.kind, GenericParamKind::Lifetime { .. }))
+                        .any(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
                 });
                 if has_lifetime_parameters {
                     // complex trait bounds like A<'a, 'b>