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lcnroli-obk
lcnr
authored and
oli-obk
committed
Add a builtin FnPtr trait
1 parent 7a06007 commit 0c13565

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20 files changed

+310
-27
lines changed

20 files changed

+310
-27
lines changed

‎compiler/rustc_const_eval/src/interpret/terminator.rs‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -382,6 +382,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
382382
| ty::InstanceDef::FnPtrShim(..)
383383
| ty::InstanceDef::DropGlue(..)
384384
| ty::InstanceDef::CloneShim(..)
385+
| ty::InstanceDef::FnPtrAddrShim(..)
385386
| ty::InstanceDef::Item(_) => {
386387
// We need MIR for this fn
387388
let Some((body, instance)) =

‎compiler/rustc_hir/src/lang_items.rs‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -166,6 +166,9 @@ language_item_table! {
166166

167167
Freeze, sym::freeze, freeze_trait, Target::Trait, GenericRequirement::Exact(0);
168168

169+
FnPtrTrait, sym::fn_ptr_trait, fn_ptr_trait, Target::Trait, GenericRequirement::Exact(0);
170+
FnPtrAddr, sym::fn_ptr_addr, fn_ptr_addr, Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
171+
169172
Drop, sym::drop, drop_trait, Target::Trait, GenericRequirement::None;
170173
Destruct, sym::destruct, destruct_trait, Target::Trait, GenericRequirement::None;
171174

‎compiler/rustc_middle/src/mir/mono.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -381,7 +381,8 @@ impl<'tcx> CodegenUnit<'tcx> {
381381
| InstanceDef::Virtual(..)
382382
| InstanceDef::ClosureOnceShim { .. }
383383
| InstanceDef::DropGlue(..)
384-
| InstanceDef::CloneShim(..) => None,
384+
| InstanceDef::CloneShim(..)
385+
| InstanceDef::FnPtrAddrShim(..) => None,
385386
}
386387
}
387388
MonoItem::Static(def_id) => def_id.as_local().map(Idx::index),

‎compiler/rustc_middle/src/mir/visit.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -340,7 +340,8 @@ macro_rules! make_mir_visitor {
340340

341341
ty::InstanceDef::FnPtrShim(_def_id, ty) |
342342
ty::InstanceDef::DropGlue(_def_id, Some(ty)) |
343-
ty::InstanceDef::CloneShim(_def_id, ty) => {
343+
ty::InstanceDef::CloneShim(_def_id, ty) |
344+
ty::InstanceDef::FnPtrAddrShim(_def_id, ty) => {
344345
// FIXME(eddyb) use a better `TyContext` here.
345346
self.visit_ty($(& $mutability)? *ty, TyContext::Location(location));
346347
}

‎compiler/rustc_middle/src/ty/instance.rs‎

Lines changed: 15 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -96,6 +96,13 @@ pub enum InstanceDef<'tcx> {
9696
///
9797
/// The `DefId` is for `Clone::clone`, the `Ty` is the type `T` with the builtin `Clone` impl.
9898
CloneShim(DefId, Ty<'tcx>),
99+
100+
/// Compiler-generated `<T as FnPtr>::addr` implementation.
101+
///
102+
/// Automatically generated for all potentially higher-ranked `fn(I) -> R` types.
103+
///
104+
/// The `DefId` is for `FnPtr::addr`, the `Ty` is the type `T`.
105+
FnPtrAddrShim(DefId, Ty<'tcx>),
99106
}
100107

101108
impl<'tcx> Instance<'tcx> {
@@ -151,7 +158,8 @@ impl<'tcx> InstanceDef<'tcx> {
151158
| InstanceDef::Intrinsic(def_id)
152159
| InstanceDef::ClosureOnceShim { call_once: def_id, track_caller: _ }
153160
| InstanceDef::DropGlue(def_id, _)
154-
| InstanceDef::CloneShim(def_id, _) => def_id,
161+
| InstanceDef::CloneShim(def_id, _)
162+
| InstanceDef::FnPtrAddrShim(def_id, _) => def_id,
155163
}
156164
}
157165

@@ -167,7 +175,8 @@ impl<'tcx> InstanceDef<'tcx> {
167175
| InstanceDef::Intrinsic(..)
168176
| InstanceDef::ClosureOnceShim { .. }
169177
| InstanceDef::DropGlue(..)
170-
| InstanceDef::CloneShim(..) => None,
178+
| InstanceDef::CloneShim(..)
179+
| InstanceDef::FnPtrAddrShim(..) => None,
171180
}
172181
}
173182

@@ -182,7 +191,8 @@ impl<'tcx> InstanceDef<'tcx> {
182191
| InstanceDef::Intrinsic(def_id)
183192
| InstanceDef::ClosureOnceShim { call_once: def_id, track_caller: _ }
184193
| InstanceDef::DropGlue(def_id, _)
185-
| InstanceDef::CloneShim(def_id, _) => ty::WithOptConstParam::unknown(def_id),
194+
| InstanceDef::CloneShim(def_id, _)
195+
| InstanceDef::FnPtrAddrShim(def_id, _) => ty::WithOptConstParam::unknown(def_id),
186196
}
187197
}
188198

@@ -268,6 +278,7 @@ impl<'tcx> InstanceDef<'tcx> {
268278
pub fn has_polymorphic_mir_body(&self) -> bool {
269279
match *self {
270280
InstanceDef::CloneShim(..)
281+
| InstanceDef::FnPtrAddrShim(..)
271282
| InstanceDef::FnPtrShim(..)
272283
| InstanceDef::DropGlue(_, Some(_)) => false,
273284
InstanceDef::ClosureOnceShim { .. }
@@ -306,6 +317,7 @@ fn fmt_instance(
306317
InstanceDef::DropGlue(_, None) => write!(f, " - shim(None)"),
307318
InstanceDef::DropGlue(_, Some(ty)) => write!(f, " - shim(Some({}))", ty),
308319
InstanceDef::CloneShim(_, ty) => write!(f, " - shim({})", ty),
320+
InstanceDef::FnPtrAddrShim(_, ty) => write!(f, " - shim({})", ty),
309321
}
310322
}
311323

‎compiler/rustc_middle/src/ty/mod.rs‎

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -2284,12 +2284,12 @@ impl<'tcx> TyCtxt<'tcx> {
22842284
def_id1: DefId,
22852285
def_id2: DefId,
22862286
) -> Option<ImplOverlapKind> {
2287+
let impl_trait_ref1 = self.impl_trait_ref(def_id1);
2288+
let impl_trait_ref2 = self.impl_trait_ref(def_id2);
22872289
// If either trait impl references an error, they're allowed to overlap,
22882290
// as one of them essentially doesn't exist.
2289-
if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.subst_identity().references_error())
2290-
|| self
2291-
.impl_trait_ref(def_id2)
2292-
.map_or(false, |tr| tr.subst_identity().references_error())
2291+
if impl_trait_ref1.map_or(false, |tr| tr.subst_identity().references_error())
2292+
|| impl_trait_ref2.map_or(false, |tr| tr.subst_identity().references_error())
22932293
{
22942294
return Some(ImplOverlapKind::Permitted { marker: false });
22952295
}
@@ -2317,11 +2317,10 @@ impl<'tcx> TyCtxt<'tcx> {
23172317
};
23182318

23192319
let is_marker_overlap = {
2320-
let is_marker_impl = |def_id: DefId| -> bool {
2321-
let trait_ref = self.impl_trait_ref(def_id);
2320+
let is_marker_impl = |trait_ref: Option<EarlyBinder<TraitRef<'_>>>| -> bool {
23222321
trait_ref.map_or(false, |tr| self.trait_def(tr.skip_binder().def_id).is_marker)
23232322
};
2324-
is_marker_impl(def_id1) && is_marker_impl(def_id2)
2323+
is_marker_impl(impl_trait_ref1) && is_marker_impl(impl_trait_ref2)
23252324
};
23262325

23272326
if is_marker_overlap {
@@ -2405,7 +2404,8 @@ impl<'tcx> TyCtxt<'tcx> {
24052404
| ty::InstanceDef::Virtual(..)
24062405
| ty::InstanceDef::ClosureOnceShim { .. }
24072406
| ty::InstanceDef::DropGlue(..)
2408-
| ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2407+
| ty::InstanceDef::CloneShim(..)
2408+
| ty::InstanceDef::FnPtrAddrShim(..) => self.mir_shims(instance),
24092409
}
24102410
}
24112411

‎compiler/rustc_mir_transform/src/inline.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -270,7 +270,8 @@ impl<'tcx> Inliner<'tcx> {
270270
| InstanceDef::FnPtrShim(..)
271271
| InstanceDef::ClosureOnceShim { .. }
272272
| InstanceDef::DropGlue(..)
273-
| InstanceDef::CloneShim(..) => return Ok(()),
273+
| InstanceDef::CloneShim(..)
274+
| InstanceDef::FnPtrAddrShim(..) => return Ok(()),
274275
}
275276

276277
if self.tcx.is_constructor(callee_def_id) {

‎compiler/rustc_mir_transform/src/inline/cycle.rs‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -84,6 +84,9 @@ pub(crate) fn mir_callgraph_reachable<'tcx>(
8484
| InstanceDef::FnPtrShim(..)
8585
| InstanceDef::ClosureOnceShim { .. }
8686
| InstanceDef::CloneShim(..) => {}
87+
88+
// This shim does not call any other functions, thus there can be no recursion.
89+
InstanceDef::FnPtrAddrShim(..) => continue,
8790
InstanceDef::DropGlue(..) => {
8891
// FIXME: A not fully substituted drop shim can cause ICEs if one attempts to
8992
// have its MIR built. Likely oli-obk just screwed up the `ParamEnv`s, so this

‎compiler/rustc_mir_transform/src/shim.rs‎

Lines changed: 37 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -77,6 +77,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'
7777
build_drop_shim(tcx, def_id, ty)
7878
}
7979
ty::InstanceDef::CloneShim(def_id, ty) => build_clone_shim(tcx, def_id, ty),
80+
ty::InstanceDef::FnPtrAddrShim(def_id, ty) => build_fn_ptr_addr_shim(tcx, def_id, ty),
8081
ty::InstanceDef::Virtual(..) => {
8182
bug!("InstanceDef::Virtual ({:?}) is for direct calls only", instance)
8283
}
@@ -861,3 +862,39 @@ pub fn build_adt_ctor(tcx: TyCtxt<'_>, ctor_id: DefId) -> Body<'_> {
861862

862863
body
863864
}
865+
866+
/// ```ignore (pseudo-impl)
867+
/// impl FnPtr for fn(u32) {
868+
/// fn addr(self) -> usize {
869+
/// self as usize
870+
/// }
871+
/// }
872+
/// ```
873+
fn build_fn_ptr_addr_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, self_ty: Ty<'tcx>) -> Body<'tcx> {
874+
assert!(matches!(self_ty.kind(), ty::FnPtr(..)), "expected fn ptr, found {self_ty}");
875+
let span = tcx.def_span(def_id);
876+
let Some(sig) = tcx.fn_sig(def_id).subst(tcx, &[self_ty.into()]).no_bound_vars() else {
877+
span_bug!(span, "FnPtr::addr with bound vars for `{self_ty}`");
878+
};
879+
let locals = local_decls_for_sig(&sig, span);
880+
881+
let source_info = SourceInfo::outermost(span);
882+
// FIXME: use `expose_addr` once we figure out whether function pointers have meaningful provenance.
883+
let rvalue = Rvalue::Cast(
884+
CastKind::FnPtrToPtr,
885+
Operand::Move(Place::from(Local::new(1))),
886+
tcx.mk_imm_ptr(tcx.types.unit),
887+
);
888+
let stmt = Statement {
889+
source_info,
890+
kind: StatementKind::Assign(Box::new((Place::return_place(), rvalue))),
891+
};
892+
let statements = vec![stmt];
893+
let start_block = BasicBlockData {
894+
statements,
895+
terminator: Some(Terminator { source_info, kind: TerminatorKind::Return }),
896+
is_cleanup: false,
897+
};
898+
let source = MirSource::from_instance(ty::InstanceDef::FnPtrAddrShim(def_id, self_ty));
899+
new_body(source, IndexVec::from_elem_n(start_block, 1), locals, sig.inputs().len(), span)
900+
}

‎compiler/rustc_monomorphize/src/collector.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -974,7 +974,8 @@ fn visit_instance_use<'tcx>(
974974
| ty::InstanceDef::ClosureOnceShim { .. }
975975
| ty::InstanceDef::Item(..)
976976
| ty::InstanceDef::FnPtrShim(..)
977-
| ty::InstanceDef::CloneShim(..) => {
977+
| ty::InstanceDef::CloneShim(..)
978+
| ty::InstanceDef::FnPtrAddrShim(..) => {
978979
output.push(create_fn_mono_item(tcx, instance, source));
979980
}
980981
}

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