Auto merge of rust-lang#128812 - nnethercote:shrink-TyKind-FnPtr, r=c…

…ompiler-errors

Shrink `TyKind::FnPtr`.

By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and `FnHeader`, which can be packed more efficiently. This reduces the size of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms. This reduces peak memory usage by a few percent on some benchmarks. It also reduces cache misses and page faults similarly, though this doesn't translate to clear cycles or wall-time improvements on CI.

r? `@compiler-errors`

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -3989,7 +3989,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, '_, 'infcx, 'tcx> {
             } else {
                 let ty = self.infcx.tcx.type_of(self.mir_def_id()).instantiate_identity();
                 match ty.kind() {
-                    ty::FnDef(_, _) | ty::FnPtr(_) => self.annotate_fn_sig(
+                    ty::FnDef(_, _) | ty::FnPtr(..) => self.annotate_fn_sig(
                         self.mir_def_id(),
                         self.infcx.tcx.fn_sig(self.mir_def_id()).instantiate_identity(),
                     ),

compiler/rustc_borrowck/src/lib.rs

@@ -1644,7 +1644,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
                     | ty::Pat(_, _)
                     | ty::Slice(_)
                     | ty::FnDef(_, _)
-                    | ty::FnPtr(_)
+                    | ty::FnPtr(..)
                     | ty::Dynamic(_, _, _)
                     | ty::Closure(_, _)
                     | ty::CoroutineClosure(_, _)
@@ -1689,7 +1689,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
                     | ty::RawPtr(_, _)
                     | ty::Ref(_, _, _)
                     | ty::FnDef(_, _)
-                    | ty::FnPtr(_)
+                    | ty::FnPtr(..)
                     | ty::Dynamic(_, _, _)
                     | ty::CoroutineWitness(..)
                     | ty::Never

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1364,7 +1364,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 debug!("func_ty.kind: {:?}", func_ty.kind());
 
                 let sig = match func_ty.kind() {
-                    ty::FnDef(..) | ty::FnPtr(_) => func_ty.fn_sig(tcx),
+                    ty::FnDef(..) | ty::FnPtr(..) => func_ty.fn_sig(tcx),
                     _ => {
                         span_mirbug!(self, term, "call to non-function {:?}", func_ty);
                         return;
@@ -2411,7 +2411,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 let ty_left = left.ty(body, tcx);
                 match ty_left.kind() {
                     // Types with regions are comparable if they have a common super-type.
-                    ty::RawPtr(_, _) | ty::FnPtr(_) => {
+                    ty::RawPtr(_, _) | ty::FnPtr(..) => {
                         let ty_right = right.ty(body, tcx);
                         let common_ty = self.infcx.next_ty_var(body.source_info(location).span);
                         self.sub_types(

compiler/rustc_codegen_cranelift/src/common.rs

@@ -69,7 +69,7 @@ fn clif_type_from_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Option<types::Typ
             FloatTy::F64 => types::F64,
             FloatTy::F128 => unimplemented!("f16_f128"),
         },
-        ty::FnPtr(_) => pointer_ty(tcx),
+        ty::FnPtr(..) => pointer_ty(tcx),
         ty::RawPtr(pointee_ty, _) | ty::Ref(_, pointee_ty, _) => {
             if has_ptr_meta(tcx, *pointee_ty) {
                 return None;

compiler/rustc_codegen_cranelift/src/value_and_place.rs

@@ -874,7 +874,7 @@ pub(crate) fn assert_assignable<'tcx>(
         (ty::Ref(_, a, _), ty::RawPtr(b, _)) | (ty::RawPtr(a, _), ty::Ref(_, b, _)) => {
             assert_assignable(fx, *a, *b, limit - 1);
         }
-        (ty::FnPtr(_), ty::FnPtr(_)) => {
+        (ty::FnPtr(..), ty::FnPtr(..)) => {
             let from_sig = fx.tcx.normalize_erasing_late_bound_regions(
                 ParamEnv::reveal_all(),
                 from_ty.fn_sig(fx.tcx),

compiler/rustc_codegen_gcc/src/type_of.rs

@@ -213,9 +213,8 @@ impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
                 // NOTE: we cannot remove this match like in the LLVM codegen because the call
                 // to fn_ptr_backend_type handle the on-stack attribute.
                 // TODO(antoyo): find a less hackish way to hande the on-stack attribute.
-                ty::FnPtr(sig) => {
-                    cx.fn_ptr_backend_type(cx.fn_abi_of_fn_ptr(sig, ty::List::empty()))
-                }
+                ty::FnPtr(sig_tys, hdr) => cx
+                    .fn_ptr_backend_type(cx.fn_abi_of_fn_ptr(sig_tys.with(hdr), ty::List::empty())),
                 _ => self.scalar_gcc_type_at(cx, scalar, Size::ZERO),
             };
             cx.scalar_types.borrow_mut().insert(self.ty, ty);

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -456,7 +456,7 @@ pub fn type_di_node<'ll, 'tcx>(cx: &CodegenCx<'ll, 'tcx>, t: Ty<'tcx>) -> &'ll D
         {
             build_pointer_or_reference_di_node(cx, t, t.boxed_ty(), unique_type_id)
         }
-        ty::FnDef(..) | ty::FnPtr(_) => build_subroutine_type_di_node(cx, unique_type_id),
+        ty::FnDef(..) | ty::FnPtr(..) => build_subroutine_type_di_node(cx, unique_type_id),
         ty::Closure(..) => build_closure_env_di_node(cx, unique_type_id),
         ty::CoroutineClosure(..) => build_closure_env_di_node(cx, unique_type_id),
         ty::Coroutine(..) => enums::build_coroutine_di_node(cx, unique_type_id),

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -331,7 +331,7 @@ fn push_debuginfo_type_name<'tcx>(
                 output.push(')');
             }
         }
-        ty::FnDef(..) | ty::FnPtr(_) => {
+        ty::FnDef(..) | ty::FnPtr(..) => {
             // We've encountered a weird 'recursive type'
             // Currently, the only way to generate such a type
             // is by using 'impl trait':

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -846,7 +846,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 ),
                 None,
             ),
-            ty::FnPtr(_) => (None, Some(callee.immediate())),
+            ty::FnPtr(..) => (None, Some(callee.immediate())),
             _ => bug!("{} is not callable", callee.layout.ty),
         };
 

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -171,7 +171,7 @@ struct LocalReturnTyVisitor<'ck, 'mir, 'tcx> {
 impl<'ck, 'mir, 'tcx> TypeVisitor<TyCtxt<'tcx>> for LocalReturnTyVisitor<'ck, 'mir, 'tcx> {
     fn visit_ty(&mut self, t: Ty<'tcx>) {
         match t.kind() {
-            ty::FnPtr(_) => {}
+            ty::FnPtr(..) => {}
             ty::Ref(_, _, hir::Mutability::Mut) => {
                 self.checker.check_op(ops::mut_ref::MutRef(self.kind));
                 t.super_visit_with(self)
@@ -726,7 +726,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                 let (mut callee, mut fn_args) = match *fn_ty.kind() {
                     ty::FnDef(def_id, fn_args) => (def_id, fn_args),
 
-                    ty::FnPtr(_) => {
+                    ty::FnPtr(..) => {
                         self.check_op(ops::FnCallIndirect);
                         return;
                     }

compiler/rustc_const_eval/src/const_eval/valtrees.rs

@@ -132,7 +132,7 @@ fn const_to_valtree_inner<'tcx>(
 
         // Technically we could allow function pointers (represented as `ty::Instance`), but this is not guaranteed to
         // agree with runtime equality tests.
-        ty::FnPtr(_) => Err(ValTreeCreationError::NonSupportedType(ty)),
+        ty::FnPtr(..) => Err(ValTreeCreationError::NonSupportedType(ty)),
 
         ty::Ref(_, _, _)  => {
             let derefd_place = ecx.deref_pointer(place)?;
@@ -353,7 +353,7 @@ pub fn valtree_to_const_value<'tcx>(
         | ty::CoroutineClosure(..)
         | ty::Coroutine(..)
         | ty::CoroutineWitness(..)
-        | ty::FnPtr(_)
+        | ty::FnPtr(..)
         | ty::Str
         | ty::Slice(_)
         | ty::Dynamic(..) => bug!("no ValTree should have been created for type {:?}", ty.kind()),

compiler/rustc_const_eval/src/interpret/cast.rs

@@ -97,7 +97,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer) => {
                 let src = self.read_immediate(src)?;
                 match cast_ty.kind() {
-                    ty::FnPtr(_) => {
+                    ty::FnPtr(..) => {
                         // No change to value
                         self.write_immediate(*src, dest)?;
                     }
@@ -230,7 +230,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         src: &ImmTy<'tcx, M::Provenance>,
         cast_to: TyAndLayout<'tcx>,
     ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
-        assert_matches!(src.layout.ty.kind(), ty::RawPtr(_, _) | ty::FnPtr(_));
+        assert_matches!(src.layout.ty.kind(), ty::RawPtr(_, _) | ty::FnPtr(..));
         assert!(cast_to.ty.is_integral());
 
         let scalar = src.to_scalar();

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -81,7 +81,7 @@ pub(crate) fn eval_nullary_intrinsic<'tcx>(
             | ty::RawPtr(_, _)
             | ty::Ref(_, _, _)
             | ty::FnDef(_, _)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Dynamic(_, _, _)
             | ty::Closure(_, _)
             | ty::CoroutineClosure(_, _)

compiler/rustc_const_eval/src/interpret/stack.rs

@@ -483,7 +483,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 | ty::Bool
                 | ty::Float(_)
                 | ty::FnDef(..)
-                | ty::FnPtr(_)
+                | ty::FnPtr(..)
                 | ty::RawPtr(..)
                 | ty::Char
                 | ty::Ref(..)

compiler/rustc_const_eval/src/interpret/step.rs

@@ -424,7 +424,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             self.tcx.mk_type_list_from_iter(extra_args.iter().map(|arg| arg.layout().ty));
 
         let (callee, fn_abi, with_caller_location) = match *func.layout.ty.kind() {
-            ty::FnPtr(_sig) => {
+            ty::FnPtr(..) => {
                 let fn_ptr = self.read_pointer(&func)?;
                 let fn_val = self.get_ptr_fn(fn_ptr)?;
                 (fn_val, self.fn_abi_of_fn_ptr(fn_sig_binder, extra_args)?, false)

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -616,7 +616,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                 self.check_safe_pointer(value, PointerKind::Ref(*mutbl))?;
                 Ok(true)
             }
-            ty::FnPtr(_sig) => {
+            ty::FnPtr(..) => {
                 let value = self.read_scalar(value, ExpectedKind::FnPtr)?;
 
                 // If we check references recursively, also check that this points to a function.

compiler/rustc_const_eval/src/util/type_name.rs

@@ -35,7 +35,7 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
             | ty::Slice(_)
             | ty::RawPtr(_, _)
             | ty::Ref(_, _, _)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Never
             | ty::Tuple(_)
             | ty::Dynamic(_, _, _) => self.pretty_print_type(ty),

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -68,7 +68,7 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
             ty::Float(FloatTy::F32) => Some(InlineAsmType::F32),
             ty::Float(FloatTy::F64) => Some(InlineAsmType::F64),
             ty::Float(FloatTy::F128) => Some(InlineAsmType::F128),
-            ty::FnPtr(_) => Some(asm_ty_isize),
+            ty::FnPtr(..) => Some(asm_ty_isize),
             ty::RawPtr(ty, _) if self.is_thin_ptr_ty(ty) => Some(asm_ty_isize),
             ty::Adt(adt, args) if adt.repr().simd() => {
                 let fields = &adt.non_enum_variant().fields;

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -951,7 +951,7 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) -> Result<(),
             } else {
                 let mut diag = match ty.kind() {
                     ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Error(_) => return Ok(()),
-                    ty::FnPtr(_) => tcx.dcx().struct_span_err(
+                    ty::FnPtr(..) => tcx.dcx().struct_span_err(
                         hir_ty.span,
                         "using function pointers as const generic parameters is forbidden",
                     ),

compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs

@@ -172,7 +172,7 @@ impl<'tcx> InherentCollect<'tcx> {
             | ty::RawPtr(_, _)
             | ty::Ref(..)
             | ty::Never
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Tuple(..) => self.check_primitive_impl(id, self_ty),
             ty::Alias(ty::Projection | ty::Inherent | ty::Opaque, _) | ty::Param(_) => {
                 Err(self.tcx.dcx().emit_err(errors::InherentNominal { span: item_span }))

compiler/rustc_hir_analysis/src/variance/constraints.rs

@@ -317,8 +317,8 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
                 self.add_constraint(current, data.index, variance);
             }
 
-            ty::FnPtr(sig) => {
-                self.add_constraints_from_sig(current, sig, variance);
+            ty::FnPtr(sig_tys, hdr) => {
+                self.add_constraints_from_sig(current, sig_tys.with(hdr), variance);
             }
 
             ty::Error(_) => {

compiler/rustc_hir_typeck/src/callee.rs

@@ -137,7 +137,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // If the callee is a bare function or a closure, then we're all set.
         match *adjusted_ty.kind() {
-            ty::FnDef(..) | ty::FnPtr(_) => {
+            ty::FnDef(..) | ty::FnPtr(..) => {
                 let adjustments = self.adjust_steps(autoderef);
                 self.apply_adjustments(callee_expr, adjustments);
                 return Some(CallStep::Builtin(adjusted_ty));
@@ -467,7 +467,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 (fn_sig, Some(def_id))
             }
             // FIXME(effects): these arms should error because we can't enforce them
-            ty::FnPtr(sig) => (sig, None),
+            ty::FnPtr(sig_tys, hdr) => (sig_tys.with(hdr), None),
             _ => {
                 for arg in arg_exprs {
                     self.check_expr(arg);

compiler/rustc_hir_typeck/src/closure.rs

@@ -336,9 +336,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .into_iter()
                     .map(|obl| (obl.predicate, obl.cause.span)),
             ),
-            ty::FnPtr(sig) => match closure_kind {
+            ty::FnPtr(sig_tys, hdr) => match closure_kind {
                 hir::ClosureKind::Closure => {
-                    let expected_sig = ExpectedSig { cause_span: None, sig };
+                    let expected_sig = ExpectedSig { cause_span: None, sig: sig_tys.with(hdr) };
                     (Some(expected_sig), Some(ty::ClosureKind::Fn))
                 }
                 hir::ClosureKind::Coroutine(_) | hir::ClosureKind::CoroutineClosure(_) => {

compiler/rustc_hir_typeck/src/coercion.rs

@@ -225,10 +225,10 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 // items to drop the unsafe qualifier.
                 self.coerce_from_fn_item(a, b)
             }
-            ty::FnPtr(a_f) => {
+            ty::FnPtr(a_sig_tys, a_hdr) => {
                 // We permit coercion of fn pointers to drop the
                 // unsafe qualifier.
-                self.coerce_from_fn_pointer(a, a_f, b)
+                self.coerce_from_fn_pointer(a, a_sig_tys.with(a_hdr), b)
             }
             ty::Closure(closure_def_id_a, args_a) => {
                 // Non-capturing closures are coercible to
@@ -788,9 +788,8 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         self.commit_if_ok(|snapshot| {
             let outer_universe = self.infcx.universe();
 
-            let result = if let ty::FnPtr(fn_ty_b) = b.kind()
-                && let (hir::Safety::Safe, hir::Safety::Unsafe) =
-                    (fn_ty_a.safety(), fn_ty_b.safety())
+            let result = if let ty::FnPtr(_, hdr_b) = b.kind()
+                && let (hir::Safety::Safe, hir::Safety::Unsafe) = (fn_ty_a.safety(), hdr_b.safety)
             {
                 let unsafe_a = self.tcx.safe_to_unsafe_fn_ty(fn_ty_a);
                 self.unify_and(unsafe_a, b, to_unsafe)
@@ -842,7 +841,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         debug!("coerce_from_fn_item(a={:?}, b={:?})", a, b);
 
         match b.kind() {
-            ty::FnPtr(b_sig) => {
+            ty::FnPtr(_, b_hdr) => {
                 let a_sig = a.fn_sig(self.tcx);
                 if let ty::FnDef(def_id, _) = *a.kind() {
                     // Intrinsics are not coercible to function pointers
@@ -852,7 +851,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
 
                     // Safe `#[target_feature]` functions are not assignable to safe fn pointers (RFC 2396).
 
-                    if b_sig.safety() == hir::Safety::Safe
+                    if b_hdr.safety == hir::Safety::Safe
                         && !self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
                     {
                         return Err(TypeError::TargetFeatureCast(def_id));
@@ -910,7 +909,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             //
             // All we care here is if any variable is being captured and not the exact paths,
             // so we check `upvars_mentioned` for root variables being captured.
-            ty::FnPtr(fn_ty)
+            ty::FnPtr(_, hdr)
                 if self
                     .tcx
                     .upvars_mentioned(closure_def_id_a.expect_local())
@@ -923,7 +922,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                 // or
                 //     `unsafe fn(arg0,arg1,...) -> _`
                 let closure_sig = args_a.as_closure().sig();
-                let safety = fn_ty.safety();
+                let safety = hdr.safety;
                 let pointer_ty =
                     Ty::new_fn_ptr(self.tcx, self.tcx.signature_unclosure(closure_sig, safety));
                 debug!("coerce_closure_to_fn(a={:?}, b={:?}, pty={:?})", a, b, pointer_ty);

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -1530,7 +1530,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     ty::Int(_) | ty::Uint(_) => Some(ty),
                     ty::Char => Some(tcx.types.u8),
                     ty::RawPtr(..) => Some(tcx.types.usize),
-                    ty::FnDef(..) | ty::FnPtr(_) => Some(tcx.types.usize),
+                    ty::FnDef(..) | ty::FnPtr(..) => Some(tcx.types.usize),
                     _ => None,
                 });
                 opt_ty.unwrap_or_else(|| self.next_int_var())

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -604,7 +604,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
     ) -> bool {
-        if let (ty::FnPtr(_), ty::Closure(def_id, _)) = (expected.kind(), found.kind()) {
+        if let (ty::FnPtr(..), ty::Closure(def_id, _)) = (expected.kind(), found.kind()) {
             if let Some(upvars) = self.tcx.upvars_mentioned(*def_id) {
                 // Report upto four upvars being captured to reduce the amount error messages
                 // reported back to the user.

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -50,7 +50,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Not all of these (e.g., unsafe fns) implement `FnOnce`,
             // so we look for these beforehand.
             // FIXME(async_closures): These don't impl `FnOnce` by default.
-            ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true,
+            ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(..) => true,
             // If it's not a simple function, look for things which implement `FnOnce`.
             _ => {
                 let Some(fn_once) = tcx.lang_items().fn_once_trait() else {

compiler/rustc_infer/src/infer/canonical/canonicalizer.rs

@@ -438,7 +438,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
             | ty::RawPtr(..)
             | ty::Ref(..)
             | ty::FnDef(..)
-            | ty::FnPtr(_)
+            | ty::FnPtr(..)
             | ty::Dynamic(..)
             | ty::Never
             | ty::Tuple(..)

compiler/rustc_lint/src/types.rs

@@ -1022,7 +1022,7 @@ fn ty_is_known_nonnull<'tcx>(
     let ty = tcx.try_normalize_erasing_regions(param_env, ty).unwrap_or(ty);
 
     match ty.kind() {
-        ty::FnPtr(_) => true,
+        ty::FnPtr(..) => true,
         ty::Ref(..) => true,
         ty::Adt(def, _) if def.is_box() && matches!(mode, CItemKind::Definition) => true,
         ty::Adt(def, args) if def.repr().transparent() && !def.is_union() => {
@@ -1473,7 +1473,8 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
 
             ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty),
 
-            ty::FnPtr(sig) => {
+            ty::FnPtr(sig_tys, hdr) => {
+                let sig = sig_tys.with(hdr);
                 if self.is_internal_abi(sig.abi()) {
                     return FfiUnsafe {
                         ty,
@@ -1709,8 +1710,8 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
             type Result = ControlFlow<Ty<'tcx>>;
 
             fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
-                if let ty::FnPtr(sig) = ty.kind()
-                    && !self.visitor.is_internal_abi(sig.abi())
+                if let ty::FnPtr(_, hdr) = ty.kind()
+                    && !self.visitor.is_internal_abi(hdr.abi)
                 {
                     self.tys.push(ty);
                 }