1 //! Definition of [`CValue`] and [`CPlace`]
5 use cranelift_codegen::ir::immediates::Offset32;
7 fn codegen_field<'tcx>(
8 fx: &mut FunctionCx<'_, '_, 'tcx>,
11 layout: TyAndLayout<'tcx>,
13 ) -> (Pointer, TyAndLayout<'tcx>) {
14 let field_offset = layout.fields.offset(field.index());
15 let field_layout = layout.field(&*fx, field.index());
17 let simple = |fx: &mut FunctionCx<'_, '_, '_>| {
18 (base.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap()), field_layout)
21 if let Some(extra) = extra {
22 if !field_layout.is_unsized() {
25 match field_layout.ty.kind() {
26 ty::Slice(..) | ty::Str | ty::Foreign(..) => simple(fx),
27 ty::Adt(def, _) if def.repr.packed() => {
28 assert_eq!(layout.align.abi.bytes(), 1);
32 // We have to align the offset for DST's
33 let unaligned_offset = field_offset.bytes();
34 let (_, unsized_align) =
35 crate::unsize::size_and_align_of_dst(fx, field_layout, extra);
37 let one = fx.bcx.ins().iconst(pointer_ty(fx.tcx), 1);
38 let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
39 let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
40 let zero = fx.bcx.ins().iconst(pointer_ty(fx.tcx), 0);
41 let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
42 let offset = fx.bcx.ins().band(and_lhs, and_rhs);
44 (base.offset_value(fx, offset), field_layout)
52 fn scalar_pair_calculate_b_offset(
57 let b_offset = a_scalar.value.size(&tcx).align_to(b_scalar.value.align(&tcx).abi);
58 Offset32::new(b_offset.bytes().try_into().unwrap())
62 #[derive(Debug, Copy, Clone)]
63 pub(crate) struct CValue<'tcx>(CValueInner, TyAndLayout<'tcx>);
65 #[derive(Debug, Copy, Clone)]
67 ByRef(Pointer, Option<Value>),
69 ByValPair(Value, Value),
72 impl<'tcx> CValue<'tcx> {
73 pub(crate) fn by_ref(ptr: Pointer, layout: TyAndLayout<'tcx>) -> CValue<'tcx> {
74 CValue(CValueInner::ByRef(ptr, None), layout)
77 pub(crate) fn by_ref_unsized(
80 layout: TyAndLayout<'tcx>,
82 CValue(CValueInner::ByRef(ptr, Some(meta)), layout)
85 pub(crate) fn by_val(value: Value, layout: TyAndLayout<'tcx>) -> CValue<'tcx> {
86 CValue(CValueInner::ByVal(value), layout)
89 pub(crate) fn by_val_pair(
92 layout: TyAndLayout<'tcx>,
94 CValue(CValueInner::ByValPair(value, extra), layout)
97 pub(crate) fn layout(&self) -> TyAndLayout<'tcx> {
102 pub(crate) fn force_stack(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> (Pointer, Option<Value>) {
105 CValueInner::ByRef(ptr, meta) => (ptr, meta),
106 CValueInner::ByVal(_) | CValueInner::ByValPair(_, _) => {
107 let cplace = CPlace::new_stack_slot(fx, layout);
108 cplace.write_cvalue(fx, self);
109 (cplace.to_ptr(), None)
114 pub(crate) fn try_to_ptr(self) -> Option<(Pointer, Option<Value>)> {
116 CValueInner::ByRef(ptr, meta) => Some((ptr, meta)),
117 CValueInner::ByVal(_) | CValueInner::ByValPair(_, _) => None,
121 /// Load a value with layout.abi of scalar
122 pub(crate) fn load_scalar(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> Value {
125 CValueInner::ByRef(ptr, None) => {
126 let clif_ty = match layout.abi {
127 Abi::Scalar(ref scalar) => scalar_to_clif_type(fx.tcx, scalar.clone()),
128 Abi::Vector { ref element, count } => {
129 scalar_to_clif_type(fx.tcx, element.clone())
130 .by(u16::try_from(count).unwrap())
133 _ => unreachable!("{:?}", layout.ty),
135 let mut flags = MemFlags::new();
137 ptr.load(fx, clif_ty, flags)
139 CValueInner::ByVal(value) => value,
140 CValueInner::ByRef(_, Some(_)) => bug!("load_scalar for unsized value not allowed"),
141 CValueInner::ByValPair(_, _) => bug!("Please use load_scalar_pair for ByValPair"),
145 /// Load a value pair with layout.abi of scalar pair
146 pub(crate) fn load_scalar_pair(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> (Value, Value) {
149 CValueInner::ByRef(ptr, None) => {
150 let (a_scalar, b_scalar) = match &layout.abi {
151 Abi::ScalarPair(a, b) => (a, b),
152 _ => unreachable!("load_scalar_pair({:?})", self),
154 let b_offset = scalar_pair_calculate_b_offset(fx.tcx, a_scalar, b_scalar);
155 let clif_ty1 = scalar_to_clif_type(fx.tcx, a_scalar.clone());
156 let clif_ty2 = scalar_to_clif_type(fx.tcx, b_scalar.clone());
157 let mut flags = MemFlags::new();
159 let val1 = ptr.load(fx, clif_ty1, flags);
160 let val2 = ptr.offset(fx, b_offset).load(fx, clif_ty2, flags);
163 CValueInner::ByRef(_, Some(_)) => {
164 bug!("load_scalar_pair for unsized value not allowed")
166 CValueInner::ByVal(_) => bug!("Please use load_scalar for ByVal"),
167 CValueInner::ByValPair(val1, val2) => (val1, val2),
171 pub(crate) fn value_field(
173 fx: &mut FunctionCx<'_, '_, 'tcx>,
178 CValueInner::ByVal(val) => match layout.abi {
179 Abi::Vector { element: _, count } => {
180 let count = u8::try_from(count).expect("SIMD type with more than 255 lanes???");
181 let field = u8::try_from(field.index()).unwrap();
182 assert!(field < count);
183 let lane = fx.bcx.ins().extractlane(val, field);
184 let field_layout = layout.field(&*fx, usize::from(field));
185 CValue::by_val(lane, field_layout)
187 _ => unreachable!("value_field for ByVal with abi {:?}", layout.abi),
189 CValueInner::ByValPair(val1, val2) => match layout.abi {
190 Abi::ScalarPair(_, _) => {
191 let val = match field.as_u32() {
194 _ => bug!("field should be 0 or 1"),
196 let field_layout = layout.field(&*fx, usize::from(field));
197 CValue::by_val(val, field_layout)
199 _ => unreachable!("value_field for ByValPair with abi {:?}", layout.abi),
201 CValueInner::ByRef(ptr, None) => {
202 let (field_ptr, field_layout) = codegen_field(fx, ptr, None, layout, field);
203 CValue::by_ref(field_ptr, field_layout)
205 CValueInner::ByRef(_, Some(_)) => todo!(),
209 pub(crate) fn unsize_value(self, fx: &mut FunctionCx<'_, '_, 'tcx>, dest: CPlace<'tcx>) {
210 crate::unsize::coerce_unsized_into(fx, self, dest);
213 /// If `ty` is signed, `const_val` must already be sign extended.
214 pub(crate) fn const_val(
215 fx: &mut FunctionCx<'_, '_, 'tcx>,
216 layout: TyAndLayout<'tcx>,
217 const_val: ty::ScalarInt,
219 assert_eq!(const_val.size(), layout.size, "{:#?}: {:?}", const_val, layout);
220 use cranelift_codegen::ir::immediates::{Ieee32, Ieee64};
222 let clif_ty = fx.clif_type(layout.ty).unwrap();
224 if let ty::Bool = layout.ty.kind() {
226 const_val == ty::ScalarInt::FALSE || const_val == ty::ScalarInt::TRUE,
227 "Invalid bool 0x{:032X}",
232 let val = match layout.ty.kind() {
233 ty::Uint(UintTy::U128) | ty::Int(IntTy::I128) => {
234 let const_val = const_val.to_bits(layout.size).unwrap();
235 let lsb = fx.bcx.ins().iconst(types::I64, const_val as u64 as i64);
236 let msb = fx.bcx.ins().iconst(types::I64, (const_val >> 64) as u64 as i64);
237 fx.bcx.ins().iconcat(lsb, msb)
239 ty::Bool | ty::Char | ty::Uint(_) | ty::Int(_) | ty::Ref(..) | ty::RawPtr(..) => {
240 fx.bcx.ins().iconst(clif_ty, const_val.to_bits(layout.size).unwrap() as i64)
242 ty::Float(FloatTy::F32) => {
243 fx.bcx.ins().f32const(Ieee32::with_bits(u32::try_from(const_val).unwrap()))
245 ty::Float(FloatTy::F64) => {
246 fx.bcx.ins().f64const(Ieee64::with_bits(u64::try_from(const_val).unwrap()))
249 "CValue::const_val for non bool/char/float/integer/pointer type {:?} is not allowed",
254 CValue::by_val(val, layout)
257 pub(crate) fn cast_pointer_to(self, layout: TyAndLayout<'tcx>) -> Self {
258 assert!(matches!(self.layout().ty.kind(), ty::Ref(..) | ty::RawPtr(..) | ty::FnPtr(..)));
259 assert!(matches!(layout.ty.kind(), ty::Ref(..) | ty::RawPtr(..) | ty::FnPtr(..)));
260 assert_eq!(self.layout().abi, layout.abi);
261 CValue(self.0, layout)
265 /// A place where you can write a value to or read a value from
266 #[derive(Debug, Copy, Clone)]
267 pub(crate) struct CPlace<'tcx> {
269 layout: TyAndLayout<'tcx>,
272 #[derive(Debug, Copy, Clone)]
273 pub(crate) enum CPlaceInner {
274 Var(Local, Variable),
275 VarPair(Local, Variable, Variable),
276 VarLane(Local, Variable, u8),
277 Addr(Pointer, Option<Value>),
280 impl<'tcx> CPlace<'tcx> {
281 pub(crate) fn layout(&self) -> TyAndLayout<'tcx> {
285 pub(crate) fn inner(&self) -> &CPlaceInner {
289 pub(crate) fn no_place(layout: TyAndLayout<'tcx>) -> CPlace<'tcx> {
290 CPlace { inner: CPlaceInner::Addr(Pointer::dangling(layout.align.pref), None), layout }
293 pub(crate) fn new_stack_slot(
294 fx: &mut FunctionCx<'_, '_, 'tcx>,
295 layout: TyAndLayout<'tcx>,
297 assert!(!layout.is_unsized());
298 if layout.size.bytes() == 0 {
299 return CPlace::no_place(layout);
302 let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
303 kind: StackSlotKind::ExplicitSlot,
304 // FIXME Don't force the size to a multiple of 16 bytes once Cranelift gets a way to
305 // specify stack slot alignment.
306 size: (u32::try_from(layout.size.bytes()).unwrap() + 15) / 16 * 16,
309 CPlace { inner: CPlaceInner::Addr(Pointer::stack_slot(stack_slot), None), layout }
312 pub(crate) fn new_var(
313 fx: &mut FunctionCx<'_, '_, 'tcx>,
315 layout: TyAndLayout<'tcx>,
317 let var = Variable::with_u32(fx.next_ssa_var);
318 fx.next_ssa_var += 1;
319 fx.bcx.declare_var(var, fx.clif_type(layout.ty).unwrap());
320 CPlace { inner: CPlaceInner::Var(local, var), layout }
323 pub(crate) fn new_var_pair(
324 fx: &mut FunctionCx<'_, '_, 'tcx>,
326 layout: TyAndLayout<'tcx>,
328 let var1 = Variable::with_u32(fx.next_ssa_var);
329 fx.next_ssa_var += 1;
330 let var2 = Variable::with_u32(fx.next_ssa_var);
331 fx.next_ssa_var += 1;
333 let (ty1, ty2) = fx.clif_pair_type(layout.ty).unwrap();
334 fx.bcx.declare_var(var1, ty1);
335 fx.bcx.declare_var(var2, ty2);
336 CPlace { inner: CPlaceInner::VarPair(local, var1, var2), layout }
339 pub(crate) fn for_ptr(ptr: Pointer, layout: TyAndLayout<'tcx>) -> CPlace<'tcx> {
340 CPlace { inner: CPlaceInner::Addr(ptr, None), layout }
343 pub(crate) fn for_ptr_with_extra(
346 layout: TyAndLayout<'tcx>,
348 CPlace { inner: CPlaceInner::Addr(ptr, Some(extra)), layout }
351 pub(crate) fn to_cvalue(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> CValue<'tcx> {
352 let layout = self.layout();
354 CPlaceInner::Var(_local, var) => {
355 let val = fx.bcx.use_var(var);
356 //fx.bcx.set_val_label(val, cranelift_codegen::ir::ValueLabel::new(var.index()));
357 CValue::by_val(val, layout)
359 CPlaceInner::VarPair(_local, var1, var2) => {
360 let val1 = fx.bcx.use_var(var1);
361 //fx.bcx.set_val_label(val1, cranelift_codegen::ir::ValueLabel::new(var1.index()));
362 let val2 = fx.bcx.use_var(var2);
363 //fx.bcx.set_val_label(val2, cranelift_codegen::ir::ValueLabel::new(var2.index()));
364 CValue::by_val_pair(val1, val2, layout)
366 CPlaceInner::VarLane(_local, var, lane) => {
367 let val = fx.bcx.use_var(var);
368 //fx.bcx.set_val_label(val, cranelift_codegen::ir::ValueLabel::new(var.index()));
369 let val = fx.bcx.ins().extractlane(val, lane);
370 CValue::by_val(val, layout)
372 CPlaceInner::Addr(ptr, extra) => {
373 if let Some(extra) = extra {
374 CValue::by_ref_unsized(ptr, extra, layout)
376 CValue::by_ref(ptr, layout)
382 pub(crate) fn to_ptr(self) -> Pointer {
383 match self.to_ptr_maybe_unsized() {
385 (_, Some(_)) => bug!("Expected sized cplace, found {:?}", self),
389 pub(crate) fn to_ptr_maybe_unsized(self) -> (Pointer, Option<Value>) {
391 CPlaceInner::Addr(ptr, extra) => (ptr, extra),
392 CPlaceInner::Var(_, _)
393 | CPlaceInner::VarPair(_, _, _)
394 | CPlaceInner::VarLane(_, _, _) => bug!("Expected CPlace::Addr, found {:?}", self),
398 pub(crate) fn write_cvalue(self, fx: &mut FunctionCx<'_, '_, 'tcx>, from: CValue<'tcx>) {
399 assert_assignable(fx, from.layout().ty, self.layout().ty);
401 self.write_cvalue_maybe_transmute(fx, from, "write_cvalue");
404 pub(crate) fn write_cvalue_transmute(
406 fx: &mut FunctionCx<'_, '_, 'tcx>,
409 self.write_cvalue_maybe_transmute(fx, from, "write_cvalue_transmute");
412 fn write_cvalue_maybe_transmute(
414 fx: &mut FunctionCx<'_, '_, 'tcx>,
416 method: &'static str,
418 fn transmute_value<'tcx>(
419 fx: &mut FunctionCx<'_, '_, 'tcx>,
424 let src_ty = fx.bcx.func.dfg.value_type(data);
428 "write_cvalue_transmute: {:?} -> {:?}",
432 let data = match (src_ty, dst_ty) {
433 (_, _) if src_ty == dst_ty => data,
435 // This is a `write_cvalue_transmute`.
436 (types::I32, types::F32)
437 | (types::F32, types::I32)
438 | (types::I64, types::F64)
439 | (types::F64, types::I64) => fx.bcx.ins().bitcast(dst_ty, data),
440 _ if src_ty.is_vector() && dst_ty.is_vector() => {
441 fx.bcx.ins().raw_bitcast(dst_ty, data)
443 _ if src_ty.is_vector() || dst_ty.is_vector() => {
444 // FIXME do something more efficient for transmutes between vectors and integers.
445 let stack_slot = fx.bcx.create_stack_slot(StackSlotData {
446 kind: StackSlotKind::ExplicitSlot,
447 // FIXME Don't force the size to a multiple of 16 bytes once Cranelift gets a way to
448 // specify stack slot alignment.
449 size: (src_ty.bytes() + 15) / 16 * 16,
452 let ptr = Pointer::stack_slot(stack_slot);
453 ptr.store(fx, data, MemFlags::trusted());
454 ptr.load(fx, dst_ty, MemFlags::trusted())
456 _ => unreachable!("write_cvalue_transmute: {:?} -> {:?}", src_ty, dst_ty),
458 //fx.bcx.set_val_label(data, cranelift_codegen::ir::ValueLabel::new(var.index()));
459 fx.bcx.def_var(var, data);
462 assert_eq!(self.layout().size, from.layout().size);
464 if fx.clif_comments.enabled() {
465 use cranelift_codegen::cursor::{Cursor, CursorPosition};
466 let cur_block = match fx.bcx.cursor().position() {
467 CursorPosition::After(block) => block,
471 fx.bcx.func.layout.last_inst(cur_block).unwrap(),
473 "{}: {:?}: {:?} <- {:?}: {:?}",
483 let dst_layout = self.layout();
484 let to_ptr = match self.inner {
485 CPlaceInner::Var(_local, var) => {
486 let data = CValue(from.0, dst_layout).load_scalar(fx);
487 let dst_ty = fx.clif_type(self.layout().ty).unwrap();
488 transmute_value(fx, var, data, dst_ty);
491 CPlaceInner::VarPair(_local, var1, var2) => {
492 let (data1, data2) = CValue(from.0, dst_layout).load_scalar_pair(fx);
493 let (dst_ty1, dst_ty2) = fx.clif_pair_type(self.layout().ty).unwrap();
494 transmute_value(fx, var1, data1, dst_ty1);
495 transmute_value(fx, var2, data2, dst_ty2);
498 CPlaceInner::VarLane(_local, var, lane) => {
499 let data = from.load_scalar(fx);
501 // First get the old vector
502 let vector = fx.bcx.use_var(var);
503 //fx.bcx.set_val_label(vector, cranelift_codegen::ir::ValueLabel::new(var.index()));
505 // Next insert the written lane into the vector
506 let vector = fx.bcx.ins().insertlane(vector, data, lane);
508 // Finally write the new vector
509 //fx.bcx.set_val_label(vector, cranelift_codegen::ir::ValueLabel::new(var.index()));
510 fx.bcx.def_var(var, vector);
514 CPlaceInner::Addr(ptr, None) => {
515 if dst_layout.size == Size::ZERO || dst_layout.abi == Abi::Uninhabited {
520 CPlaceInner::Addr(_, Some(_)) => bug!("Can't write value to unsized place {:?}", self),
523 let mut flags = MemFlags::new();
525 match from.layout().abi {
526 // FIXME make Abi::Vector work too
528 let val = from.load_scalar(fx);
529 to_ptr.store(fx, val, flags);
532 Abi::ScalarPair(ref a_scalar, ref b_scalar) => {
533 let (value, extra) = from.load_scalar_pair(fx);
534 let b_offset = scalar_pair_calculate_b_offset(fx.tcx, a_scalar, b_scalar);
535 to_ptr.store(fx, value, flags);
536 to_ptr.offset(fx, b_offset).store(fx, extra, flags);
543 CValueInner::ByVal(val) => {
544 to_ptr.store(fx, val, flags);
546 CValueInner::ByValPair(_, _) => {
547 bug!("Non ScalarPair abi {:?} for ByValPair CValue", dst_layout.abi);
549 CValueInner::ByRef(from_ptr, None) => {
550 let from_addr = from_ptr.get_addr(fx);
551 let to_addr = to_ptr.get_addr(fx);
552 let src_layout = from.1;
553 let size = dst_layout.size.bytes();
554 let src_align = src_layout.align.abi.bytes() as u8;
555 let dst_align = dst_layout.align.abi.bytes() as u8;
556 fx.bcx.emit_small_memory_copy(
557 fx.cx.module.target_config(),
566 CValueInner::ByRef(_, Some(_)) => todo!(),
570 pub(crate) fn place_field(
572 fx: &mut FunctionCx<'_, '_, 'tcx>,
575 let layout = self.layout();
578 CPlaceInner::Var(local, var) => {
579 if let Abi::Vector { .. } = layout.abi {
581 inner: CPlaceInner::VarLane(local, var, field.as_u32().try_into().unwrap()),
582 layout: layout.field(fx, field.as_u32().try_into().unwrap()),
586 CPlaceInner::VarPair(local, var1, var2) => {
587 let layout = layout.field(&*fx, field.index());
589 match field.as_u32() {
590 0 => return CPlace { inner: CPlaceInner::Var(local, var1), layout },
591 1 => return CPlace { inner: CPlaceInner::Var(local, var2), layout },
592 _ => unreachable!("field should be 0 or 1"),
598 let (base, extra) = self.to_ptr_maybe_unsized();
600 let (field_ptr, field_layout) = codegen_field(fx, base, extra, layout, field);
601 if field_layout.is_unsized() {
602 CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
604 CPlace::for_ptr(field_ptr, field_layout)
608 pub(crate) fn place_index(
610 fx: &mut FunctionCx<'_, '_, 'tcx>,
613 let (elem_layout, ptr) = match self.layout().ty.kind() {
614 ty::Array(elem_ty, _) => (fx.layout_of(elem_ty), self.to_ptr()),
615 ty::Slice(elem_ty) => (fx.layout_of(elem_ty), self.to_ptr_maybe_unsized().0),
616 _ => bug!("place_index({:?})", self.layout().ty),
619 let offset = fx.bcx.ins().imul_imm(index, elem_layout.size.bytes() as i64);
621 CPlace::for_ptr(ptr.offset_value(fx, offset), elem_layout)
624 pub(crate) fn place_deref(self, fx: &mut FunctionCx<'_, '_, 'tcx>) -> CPlace<'tcx> {
625 let inner_layout = fx.layout_of(self.layout().ty.builtin_deref(true).unwrap().ty);
626 if has_ptr_meta(fx.tcx, inner_layout.ty) {
627 let (addr, extra) = self.to_cvalue(fx).load_scalar_pair(fx);
628 CPlace::for_ptr_with_extra(Pointer::new(addr), extra, inner_layout)
630 CPlace::for_ptr(Pointer::new(self.to_cvalue(fx).load_scalar(fx)), inner_layout)
634 pub(crate) fn place_ref(
636 fx: &mut FunctionCx<'_, '_, 'tcx>,
637 layout: TyAndLayout<'tcx>,
639 if has_ptr_meta(fx.tcx, self.layout().ty) {
640 let (ptr, extra) = self.to_ptr_maybe_unsized();
643 extra.expect("unsized type without metadata"),
647 CValue::by_val(self.to_ptr().get_addr(fx), layout)
651 pub(crate) fn downcast_variant(
653 fx: &FunctionCx<'_, '_, 'tcx>,
656 assert!(!self.layout().is_unsized());
657 let layout = self.layout().for_variant(fx, variant);
658 CPlace { inner: self.inner, layout }
663 pub(crate) fn assert_assignable<'tcx>(
664 fx: &FunctionCx<'_, '_, 'tcx>,
668 match (from_ty.kind(), to_ty.kind()) {
669 (ty::Ref(_, a, _), ty::Ref(_, b, _))
671 ty::RawPtr(TypeAndMut { ty: a, mutbl: _ }),
672 ty::RawPtr(TypeAndMut { ty: b, mutbl: _ }),
674 assert_assignable(fx, a, b);
676 (ty::Ref(_, a, _), ty::RawPtr(TypeAndMut { ty: b, mutbl: _ }))
677 | (ty::RawPtr(TypeAndMut { ty: a, mutbl: _ }), ty::Ref(_, b, _)) => {
678 assert_assignable(fx, a, b);
680 (ty::FnPtr(_), ty::FnPtr(_)) => {
681 let from_sig = fx.tcx.normalize_erasing_late_bound_regions(
682 ParamEnv::reveal_all(),
683 from_ty.fn_sig(fx.tcx),
687 .normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), to_ty.fn_sig(fx.tcx));
690 "Can't write fn ptr with incompatible sig {:?} to place with sig {:?}\n\n{:#?}",
691 from_sig, to_sig, fx,
693 // fn(&T) -> for<'l> fn(&'l T) is allowed
695 (&ty::Dynamic(from_traits, _), &ty::Dynamic(to_traits, _)) => {
696 for (from, to) in from_traits.iter().zip(to_traits) {
698 fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), from);
699 let to = fx.tcx.normalize_erasing_late_bound_regions(ParamEnv::reveal_all(), to);
702 "Can't write trait object of incompatible traits {:?} to place with traits {:?}\n\n{:#?}",
703 from_traits, to_traits, fx,
706 // dyn for<'r> Trait<'r> -> dyn Trait<'_> is allowed
708 (&ty::Adt(adt_def_a, substs_a), &ty::Adt(adt_def_b, substs_b))
709 if adt_def_a.did == adt_def_b.did =>
711 let mut types_a = substs_a.types();
712 let mut types_b = substs_b.types();
714 match (types_a.next(), types_b.next()) {
715 (Some(a), Some(b)) => assert_assignable(fx, a, b),
716 (None, None) => return,
717 (Some(_), None) | (None, Some(_)) => panic!("{:#?}/{:#?}", from_ty, to_ty),
724 "Can't write value with incompatible type {:?} to place with type {:?}\n\n{:#?}",