[thirdparty/gcc.git] / gcc / rust / typecheck / rust-casts.cc

// Copyright (C) 2020-2025 Free Software Foundation, Inc.

// This file is part of GCC.

// GCC is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 3, or (at your option) any later
// version.

// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.

// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.

#include "rust-casts.h"
#include "rust-tyty-util.h"

namespace Rust {
namespace Resolver {

TypeCastRules::TypeCastRules (location_t locus, TyTy::TyWithLocation from,
			      TyTy::TyWithLocation to)
  : locus (locus), from (from), to (to)
{}

TypeCoercionRules::CoercionResult
TypeCastRules::resolve (location_t locus, TyTy::TyWithLocation from,
			TyTy::TyWithLocation to, bool emit_error)
{
  TypeCastRules cast_rules (locus, from, to);
  return cast_rules.check (emit_error);
}

TypeCoercionRules::CoercionResult
TypeCastRules::check (bool emit_error)
{
  // try the simple cast rules
  auto simple_cast = cast_rules ();
  if (!simple_cast.is_error ())
    return simple_cast;

  // https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L565-L582
  auto possible_coercion
    = TypeCoercionRules::TryCoerce (from.get_ty (), to.get_ty (), locus,
				    true /*allow-autoderef*/,
				    true /*is_cast_site*/);
  if (!possible_coercion.is_error ())
    {
      // given the attempt was ok we need to ensure we perform it so that any
      // inference variables are unified correctly
      return TypeCoercionRules::Coerce (from.get_ty (), to.get_ty (), locus,
					true /*allow-autoderef*/,
					true /*is_cast_site*/);
    }

  if (emit_error)
    TypeCastRules::emit_cast_error (locus, from, to);

  return TypeCoercionRules::CoercionResult::get_error ();
}

TypeCoercionRules::CoercionResult
TypeCastRules::cast_rules ()
{
  // https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L596
  // https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L654

  TyTy::BaseType *from_type = from.get_ty ()->destructure ();

  rust_debug ("cast_rules from={%s} to={%s}", from_type->debug_str ().c_str (),
	      to.get_ty ()->debug_str ().c_str ());
  switch (from_type->get_kind ())
    {
    case TyTy::TypeKind::INFER:
      {
	TyTy::InferType *from_infer
	  = static_cast<TyTy::InferType *> (from_type);
	switch (from_infer->get_infer_kind ())
	  {
	  case TyTy::InferType::InferTypeKind::GENERAL:
	    return TypeCoercionRules::CoercionResult{{},
						     to.get_ty ()->clone ()};

	  case TyTy::InferType::InferTypeKind::INTEGRAL:
	    switch (to.get_ty ()->get_kind ())
	      {
	      case TyTy::TypeKind::CHAR:
		{
		  // only u8 and char
		  bool was_uint
		    = from.get_ty ()->get_kind () == TyTy::TypeKind::UINT;
		  bool was_u8
		    = was_uint
		      && (static_cast<TyTy::UintType *> (from.get_ty ())
			    ->get_uint_kind ()
			  == TyTy::UintType::UintKind::U8);
		  if (was_u8)
		    return TypeCoercionRules::CoercionResult{
		      {}, to.get_ty ()->clone ()};
		}
		break;

	      case TyTy::TypeKind::USIZE:
	      case TyTy::TypeKind::ISIZE:
	      case TyTy::TypeKind::UINT:
	      case TyTy::TypeKind::INT:
	      case TyTy::TypeKind::POINTER:
		return TypeCoercionRules::CoercionResult{
		  {}, to.get_ty ()->clone ()};

	      case TyTy::TypeKind::INFER:
		{
		  TyTy::InferType *to_infer
		    = static_cast<TyTy::InferType *> (to.get_ty ());

		  switch (to_infer->get_infer_kind ())
		    {
		    case TyTy::InferType::InferTypeKind::GENERAL:
		    case TyTy::InferType::InferTypeKind::INTEGRAL:
		      return TypeCoercionRules::CoercionResult{
			{}, to.get_ty ()->clone ()};

		    default:
		      return TypeCoercionRules::CoercionResult::get_error ();
		    }
		}
		break;

	      default:
		return TypeCoercionRules::CoercionResult::get_error ();
	      }
	    break;

	  case TyTy::InferType::InferTypeKind::FLOAT:
	    switch (to.get_ty ()->get_kind ())
	      {
	      case TyTy::TypeKind::USIZE:
	      case TyTy::TypeKind::ISIZE:
	      case TyTy::TypeKind::UINT:
	      case TyTy::TypeKind::INT:
		return TypeCoercionRules::CoercionResult{
		  {}, to.get_ty ()->clone ()};

	      case TyTy::TypeKind::INFER:
		{
		  TyTy::InferType *to_infer
		    = static_cast<TyTy::InferType *> (to.get_ty ());

		  switch (to_infer->get_infer_kind ())
		    {
		    case TyTy::InferType::InferTypeKind::GENERAL:
		    case TyTy::InferType::InferTypeKind::FLOAT:
		      return TypeCoercionRules::CoercionResult{
			{}, to.get_ty ()->clone ()};

		    default:
		      return TypeCoercionRules::CoercionResult::get_error ();
		    }
		}
		break;

	      default:
		return TypeCoercionRules::CoercionResult::get_error ();
	      }
	    break;
	  }
      }
      break;

    case TyTy::TypeKind::BOOL:
      switch (to.get_ty ()->get_kind ())
	{
	case TyTy::TypeKind::INFER:
	case TyTy::TypeKind::USIZE:
	case TyTy::TypeKind::ISIZE:
	case TyTy::TypeKind::UINT:
	case TyTy::TypeKind::INT:
	  return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};

	default:
	  return TypeCoercionRules::CoercionResult::get_error ();
	}
      break;

    case TyTy::TypeKind::CHAR:
    case TyTy::TypeKind::USIZE:
    case TyTy::TypeKind::ISIZE:
    case TyTy::TypeKind::UINT:
    case TyTy::TypeKind::INT:
      switch (to.get_ty ()->get_kind ())
	{
	case TyTy::TypeKind::CHAR:
	  {
	    // only u8 and char
	    bool was_uint = from.get_ty ()->get_kind () == TyTy::TypeKind::UINT;
	    bool was_u8 = was_uint
			  && (static_cast<TyTy::UintType *> (from.get_ty ())
				->get_uint_kind ()
			      == TyTy::UintType::UintKind::U8);
	    if (was_u8)
	      return TypeCoercionRules::CoercionResult{{},
						       to.get_ty ()->clone ()};
	  }
	  break;

	case TyTy::TypeKind::FLOAT:
	  {
	    // can only do this for number types not char
	    bool from_char
	      = from.get_ty ()->get_kind () == TyTy::TypeKind::CHAR;
	    if (!from_char)
	      return TypeCoercionRules::CoercionResult{{},
						       to.get_ty ()->clone ()};
	  }
	  break;

	case TyTy::TypeKind::POINTER:
	  {
	    // char can't be casted as a ptr
	    bool from_char
	      = from.get_ty ()->get_kind () == TyTy::TypeKind::CHAR;
	    if (!from_char)
	      return TypeCoercionRules::CoercionResult{{},
						       to.get_ty ()->clone ()};
	  }
	  break;

	case TyTy::TypeKind::INFER:
	case TyTy::TypeKind::USIZE:
	case TyTy::TypeKind::ISIZE:
	case TyTy::TypeKind::UINT:
	case TyTy::TypeKind::INT:
	  return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};

	default:
	  return TypeCoercionRules::CoercionResult::get_error ();
	}
      break;

    case TyTy::TypeKind::FLOAT:
      switch (to.get_ty ()->get_kind ())
	{
	case TyTy::TypeKind::USIZE:
	case TyTy::TypeKind::ISIZE:
	case TyTy::TypeKind::UINT:
	case TyTy::TypeKind::INT:
	  return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};

	case TyTy::TypeKind::FLOAT:
	  return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};

	case TyTy::TypeKind::INFER:
	  {
	    TyTy::InferType *to_infer
	      = static_cast<TyTy::InferType *> (to.get_ty ());

	    switch (to_infer->get_infer_kind ())
	      {
	      case TyTy::InferType::InferTypeKind::GENERAL:
	      case TyTy::InferType::InferTypeKind::FLOAT:
		return TypeCoercionRules::CoercionResult{
		  {}, to.get_ty ()->clone ()};

	      default:
		return TypeCoercionRules::CoercionResult::get_error ();
	      }
	  }
	  break;

	default:
	  return TypeCoercionRules::CoercionResult::get_error ();
	}
      break;

    case TyTy::TypeKind::REF:
    case TyTy::TypeKind::FNPTR:
    case TyTy::TypeKind::POINTER:
      switch (to.get_ty ()->get_kind ())
	{
	case TyTy::TypeKind::USIZE:
	case TyTy::TypeKind::ISIZE:
	case TyTy::TypeKind::UINT:
	case TyTy::TypeKind::INT:
	  {
	    // refs should not cast to numeric type
	    auto kind = from.get_ty ()->get_kind ();
	    bool from_ptr = kind == TyTy::TypeKind::POINTER
			    || kind == TyTy::TypeKind::FNPTR;
	    if (from_ptr)
	      {
		return TypeCoercionRules::CoercionResult{
		  {}, to.get_ty ()->clone ()};
	      }
	  }
	  break;

	case TyTy::TypeKind::REF:
	case TyTy::TypeKind::POINTER:
	  return check_ptr_ptr_cast ();

	default:
	  return TypeCoercionRules::CoercionResult::get_error ();
	}
      break;

    default:
      return TypeCoercionRules::CoercionResult::get_error ();
    }

  return TypeCoercionRules::CoercionResult::get_error ();
}

TypeCoercionRules::CoercionResult
TypeCastRules::check_ptr_ptr_cast ()
{
  rust_debug ("check_ptr_ptr_cast from={%s} to={%s}",
	      from.get_ty ()->debug_str ().c_str (),
	      to.get_ty ()->debug_str ().c_str ());

  bool from_is_ref = from.get_ty ()->get_kind () == TyTy::TypeKind::REF;
  bool to_is_ref = to.get_ty ()->get_kind () == TyTy::TypeKind::REF;
  bool from_is_ptr = from.get_ty ()->get_kind () == TyTy::TypeKind::POINTER;
  bool to_is_ptr = to.get_ty ()->get_kind () == TyTy::TypeKind::POINTER;

  if (from_is_ptr && to_is_ptr)
    {
      // mutability is ignored here as all pointer usage requires unsafe
      return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
    }
  else if (from_is_ref && to_is_ref)
    {
      const auto &from_ref = *from.get_ty ()->as<TyTy::ReferenceType> ();
      const auto &to_ref = *to.get_ty ()->as<TyTy::ReferenceType> ();

      if (from_ref.is_dyn_object () != to_ref.is_dyn_object ())
	{
	  // this needs to be handled by coercion logic
	  return TypeCoercionRules::CoercionResult::get_error ();
	}

      // are the underlying types safely simple castable?
      const auto to_underly = to_ref.get_base ();
      const auto from_underly = from_ref.get_base ();
      auto res = resolve (locus, TyTy::TyWithLocation (from_underly),
			  TyTy::TyWithLocation (to_underly), false);
      if (res.is_error ())
	{
	  // this needs to be handled by coercion logic
	  return TypeCoercionRules::CoercionResult::get_error ();
	}

      // mutability must be coerceable
      TyTy::ReferenceType &f
	= static_cast<TyTy::ReferenceType &> (*from.get_ty ());
      TyTy::ReferenceType &t
	= static_cast<TyTy::ReferenceType &> (*to.get_ty ());

      if (TypeCoercionRules::coerceable_mutability (f.mutability (),
						    t.mutability ()))
	{
	  return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	}
    }

  return TypeCoercionRules::CoercionResult::get_error ();
}

void
TypeCastRules::emit_cast_error (location_t locus, TyTy::TyWithLocation from,
				TyTy::TyWithLocation to)
{
  rich_location r (line_table, locus);
  r.add_range (from.get_locus ());
  r.add_range (to.get_locus ());
  ErrorCode error_code;
  std::string error_msg;
  switch (to.get_ty ()->get_kind ())
    {
    case TyTy::TypeKind::BOOL:
      error_msg = "cannot cast %qs as %qs";
      error_code = ErrorCode::E0054;
      break;
    case TyTy::TypeKind::CHAR:
      error_msg
	+= "cannot cast %qs as %qs, only %<u8%> can be cast as %<char%>";
      error_code = ErrorCode::E0604;
      break;
    case TyTy::TypeKind::SLICE:
      error_msg = "cast to unsized type: %qs as %qs";
      error_code = ErrorCode::E0620;
      break;

    default:
      error_msg = "casting %qs as %qs is invalid";
      error_code = ErrorCode::E0606;
      break;
    }
  rust_error_at (r, error_code, error_msg.c_str (),
		 from.get_ty ()->get_name ().c_str (),
		 to.get_ty ()->get_name ().c_str ());
}

} // namespace Resolver
} // namespace Rust
Commit	Line	Data
6441eb6d	1	// Copyright (C) 2020-2025 Free Software Foundation, Inc.
06688fe4 PH	2
	3	// This file is part of GCC.
	4
	5	// GCC is free software; you can redistribute it and/or modify it under
	6	// the terms of the GNU General Public License as published by the Free
	7	// Software Foundation; either version 3, or (at your option) any later
	8	// version.
	9
	10	// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
	11	// WARRANTY; without even the implied warranty of MERCHANTABILITY or
	12	// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	13	// for more details.
	14
	15	// You should have received a copy of the GNU General Public License
	16	// along with GCC; see the file COPYING3. If not see
	17	// <http://www.gnu.org/licenses/>.
	18
	19	#include "rust-casts.h"
04b29afc	20	#include "rust-tyty-util.h"
06688fe4 PH	21
	22	namespace Rust {
	23	namespace Resolver {
	24
d991a3f1	25	TypeCastRules::TypeCastRules (location_t locus, TyTy::TyWithLocation from,
06688fe4 PH	26	TyTy::TyWithLocation to)
	27	: locus (locus), from (from), to (to)
	28	{}
	29
	30	TypeCoercionRules::CoercionResult
d991a3f1	31	TypeCastRules::resolve (location_t locus, TyTy::TyWithLocation from,
04b29afc	32	TyTy::TyWithLocation to, bool emit_error)
06688fe4 PH	33	{
06688fe4 PH	34	TypeCastRules cast_rules (locus, from, to);
04b29afc	35	return cast_rules.check (emit_error);
06688fe4 PH	36	}
	37
	38	TypeCoercionRules::CoercionResult
04b29afc	39	TypeCastRules::check (bool emit_error)
06688fe4	40	{
04b29afc PH	41	// try the simple cast rules
	42	auto simple_cast = cast_rules ();
	43	if (!simple_cast.is_error ())
	44	return simple_cast;
	45
06688fe4 PH	46	// https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L565-L582
06688fe4 PH	47	auto possible_coercion
e6750011	48	= TypeCoercionRules::TryCoerce (from.get_ty (), to.get_ty (), locus,
8ae7e93d PH	49	true /allow-autoderef/,
8ae7e93d PH	50	true /is_cast_site/);
06688fe4	51	if (!possible_coercion.is_error ())
1b34e40e PH	52	{
	53	// given the attempt was ok we need to ensure we perform it so that any
	54	// inference variables are unified correctly
	55	return TypeCoercionRules::Coerce (from.get_ty (), to.get_ty (), locus,
8ae7e93d PH	56	true /allow-autoderef/,
8ae7e93d PH	57	true /is_cast_site/);
1b34e40e	58	}
06688fe4	59
04b29afc PH	60	if (emit_error)
04b29afc PH	61	TypeCastRules::emit_cast_error (locus, from, to);
06688fe4	62
06688fe4 PH	63	return TypeCoercionRules::CoercionResult::get_error ();
	64	}
	65
	66	TypeCoercionRules::CoercionResult
	67	TypeCastRules::cast_rules ()
	68	{
	69	// https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L596
	70	// https://github.com/rust-lang/rust/blob/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/compiler/rustc_typeck/src/check/cast.rs#L654
	71
525110ae	72	TyTy::BaseType *from_type = from.get_ty ()->destructure ();
	73
	74	rust_debug ("cast_rules from={%s} to={%s}", from_type->debug_str ().c_str (),
06688fe4	75	to.get_ty ()->debug_str ().c_str ());
525110ae	76	switch (from_type->get_kind ())
06688fe4	77	{
dd65cf1d MP	78	case TyTy::TypeKind::INFER:
dd65cf1d MP	79	{
06688fe4	80	TyTy::InferType *from_infer
525110ae	81	= static_cast<TyTy::InferType *> (from_type);
06688fe4 PH	82	switch (from_infer->get_infer_kind ())
	83	{
	84	case TyTy::InferType::InferTypeKind::GENERAL:
	85	return TypeCoercionRules::CoercionResult{{},
	86	to.get_ty ()->clone ()};
	87
	88	case TyTy::InferType::InferTypeKind::INTEGRAL:
	89	switch (to.get_ty ()->get_kind ())
	90	{
dd65cf1d MP	91	case TyTy::TypeKind::CHAR:
dd65cf1d MP	92	{
bdb4e293 EM	93	// only u8 and char
	94	bool was_uint
	95	= from.get_ty ()->get_kind () == TyTy::TypeKind::UINT;
	96	bool was_u8
	97	= was_uint
	98	&& (static_cast<TyTy::UintType *> (from.get_ty ())
	99	->get_uint_kind ()
	100	== TyTy::UintType::UintKind::U8);
	101	if (was_u8)
	102	return TypeCoercionRules::CoercionResult{
	103	{}, to.get_ty ()->clone ()};
	104	}
	105	break;
	106
06688fe4 PH	107	case TyTy::TypeKind::USIZE:
	108	case TyTy::TypeKind::ISIZE:
	109	case TyTy::TypeKind::UINT:
	110	case TyTy::TypeKind::INT:
	111	case TyTy::TypeKind::POINTER:
	112	return TypeCoercionRules::CoercionResult{
	113	{}, to.get_ty ()->clone ()};
	114
dd65cf1d MP	115	case TyTy::TypeKind::INFER:
dd65cf1d MP	116	{
06688fe4 PH	117	TyTy::InferType *to_infer
	118	= static_cast<TyTy::InferType *> (to.get_ty ());
	119
	120	switch (to_infer->get_infer_kind ())
	121	{
	122	case TyTy::InferType::InferTypeKind::GENERAL:
	123	case TyTy::InferType::InferTypeKind::INTEGRAL:
	124	return TypeCoercionRules::CoercionResult{
	125	{}, to.get_ty ()->clone ()};
	126
	127	default:
	128	return TypeCoercionRules::CoercionResult::get_error ();
	129	}
	130	}
	131	break;
	132
	133	default:
	134	return TypeCoercionRules::CoercionResult::get_error ();
	135	}
	136	break;
	137
	138	case TyTy::InferType::InferTypeKind::FLOAT:
	139	switch (to.get_ty ()->get_kind ())
	140	{
	141	case TyTy::TypeKind::USIZE:
	142	case TyTy::TypeKind::ISIZE:
	143	case TyTy::TypeKind::UINT:
	144	case TyTy::TypeKind::INT:
	145	return TypeCoercionRules::CoercionResult{
	146	{}, to.get_ty ()->clone ()};
	147
dd65cf1d MP	148	case TyTy::TypeKind::INFER:
dd65cf1d MP	149	{
06688fe4 PH	150	TyTy::InferType *to_infer
	151	= static_cast<TyTy::InferType *> (to.get_ty ());
	152
	153	switch (to_infer->get_infer_kind ())
	154	{
	155	case TyTy::InferType::InferTypeKind::GENERAL:
	156	case TyTy::InferType::InferTypeKind::FLOAT:
	157	return TypeCoercionRules::CoercionResult{
	158	{}, to.get_ty ()->clone ()};
	159
	160	default:
	161	return TypeCoercionRules::CoercionResult::get_error ();
	162	}
	163	}
	164	break;
	165
	166	default:
	167	return TypeCoercionRules::CoercionResult::get_error ();
	168	}
	169	break;
	170	}
	171	}
	172	break;
	173
	174	case TyTy::TypeKind::BOOL:
	175	switch (to.get_ty ()->get_kind ())
	176	{
	177	case TyTy::TypeKind::INFER:
	178	case TyTy::TypeKind::USIZE:
	179	case TyTy::TypeKind::ISIZE:
	180	case TyTy::TypeKind::UINT:
	181	case TyTy::TypeKind::INT:
	182	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	183
	184	default:
	185	return TypeCoercionRules::CoercionResult::get_error ();
	186	}
	187	break;
	188
	189	case TyTy::TypeKind::CHAR:
	190	case TyTy::TypeKind::USIZE:
	191	case TyTy::TypeKind::ISIZE:
	192	case TyTy::TypeKind::UINT:
	193	case TyTy::TypeKind::INT:
	194	switch (to.get_ty ()->get_kind ())
	195	{
dd65cf1d MP	196	case TyTy::TypeKind::CHAR:
dd65cf1d MP	197	{
06688fe4 PH	198	// only u8 and char
	199	bool was_uint = from.get_ty ()->get_kind () == TyTy::TypeKind::UINT;
	200	bool was_u8 = was_uint
	201	&& (static_cast<TyTy::UintType *> (from.get_ty ())
	202	->get_uint_kind ()
	203	== TyTy::UintType::UintKind::U8);
	204	if (was_u8)
	205	return TypeCoercionRules::CoercionResult{{},
	206	to.get_ty ()->clone ()};
	207	}
	208	break;
	209
dd65cf1d MP	210	case TyTy::TypeKind::FLOAT:
dd65cf1d MP	211	{
80bc600e PH	212	// can only do this for number types not char
	213	bool from_char
	214	= from.get_ty ()->get_kind () == TyTy::TypeKind::CHAR;
	215	if (!from_char)
	216	return TypeCoercionRules::CoercionResult{{},
	217	to.get_ty ()->clone ()};
	218	}
	219	break;
	220
dd65cf1d MP	221	case TyTy::TypeKind::POINTER:
dd65cf1d MP	222	{
3396da35 N	223	// char can't be casted as a ptr
	224	bool from_char
	225	= from.get_ty ()->get_kind () == TyTy::TypeKind::CHAR;
	226	if (!from_char)
	227	return TypeCoercionRules::CoercionResult{{},
	228	to.get_ty ()->clone ()};
	229	}
	230	break;
	231
06688fe4 PH	232	case TyTy::TypeKind::INFER:
	233	case TyTy::TypeKind::USIZE:
	234	case TyTy::TypeKind::ISIZE:
	235	case TyTy::TypeKind::UINT:
	236	case TyTy::TypeKind::INT:
	237	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	238
	239	default:
	240	return TypeCoercionRules::CoercionResult::get_error ();
	241	}
	242	break;
	243
	244	case TyTy::TypeKind::FLOAT:
	245	switch (to.get_ty ()->get_kind ())
	246	{
1cad5f2b N	247	case TyTy::TypeKind::USIZE:
	248	case TyTy::TypeKind::ISIZE:
	249	case TyTy::TypeKind::UINT:
	250	case TyTy::TypeKind::INT:
	251	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	252
06688fe4 PH	253	case TyTy::TypeKind::FLOAT:
	254	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	255
dd65cf1d MP	256	case TyTy::TypeKind::INFER:
dd65cf1d MP	257	{
06688fe4 PH	258	TyTy::InferType *to_infer
	259	= static_cast<TyTy::InferType *> (to.get_ty ());
	260
	261	switch (to_infer->get_infer_kind ())
	262	{
	263	case TyTy::InferType::InferTypeKind::GENERAL:
	264	case TyTy::InferType::InferTypeKind::FLOAT:
	265	return TypeCoercionRules::CoercionResult{
	266	{}, to.get_ty ()->clone ()};
	267
	268	default:
	269	return TypeCoercionRules::CoercionResult::get_error ();
	270	}
	271	}
	272	break;
	273
	274	default:
	275	return TypeCoercionRules::CoercionResult::get_error ();
	276	}
	277	break;
	278
	279	case TyTy::TypeKind::REF:
94b82f54	280	case TyTy::TypeKind::FNPTR:
06688fe4 PH	281	case TyTy::TypeKind::POINTER:
	282	switch (to.get_ty ()->get_kind ())
	283	{
3396da35 N	284	case TyTy::TypeKind::USIZE:
	285	case TyTy::TypeKind::ISIZE:
	286	case TyTy::TypeKind::UINT:
dd65cf1d MP	287	case TyTy::TypeKind::INT:
dd65cf1d MP	288	{
3396da35	289	// refs should not cast to numeric type
94b82f54 PEP	290	auto kind = from.get_ty ()->get_kind ();
	291	bool from_ptr = kind == TyTy::TypeKind::POINTER
	292	\|\| kind == TyTy::TypeKind::FNPTR;
3396da35 N	293	if (from_ptr)
	294	{
	295	return TypeCoercionRules::CoercionResult{
	296	{}, to.get_ty ()->clone ()};
	297	}
	298	}
	299	break;
	300
06688fe4 PH	301	case TyTy::TypeKind::REF:
	302	case TyTy::TypeKind::POINTER:
	303	return check_ptr_ptr_cast ();
	304
06688fe4 PH	305	default:
	306	return TypeCoercionRules::CoercionResult::get_error ();
	307	}
	308	break;
	309
	310	default:
	311	return TypeCoercionRules::CoercionResult::get_error ();
	312	}
	313
	314	return TypeCoercionRules::CoercionResult::get_error ();
	315	}
	316
	317	TypeCoercionRules::CoercionResult
	318	TypeCastRules::check_ptr_ptr_cast ()
	319	{
	320	rust_debug ("check_ptr_ptr_cast from={%s} to={%s}",
	321	from.get_ty ()->debug_str ().c_str (),
	322	to.get_ty ()->debug_str ().c_str ());
	323
	324	bool from_is_ref = from.get_ty ()->get_kind () == TyTy::TypeKind::REF;
	325	bool to_is_ref = to.get_ty ()->get_kind () == TyTy::TypeKind::REF;
	326	bool from_is_ptr = from.get_ty ()->get_kind () == TyTy::TypeKind::POINTER;
	327	bool to_is_ptr = to.get_ty ()->get_kind () == TyTy::TypeKind::POINTER;
	328
	329	if (from_is_ptr && to_is_ptr)
	330	{
	331	// mutability is ignored here as all pointer usage requires unsafe
	332	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	333	}
	334	else if (from_is_ref && to_is_ref)
	335	{
04b29afc PH	336	const auto &from_ref = *from.get_ty ()->as<TyTy::ReferenceType> ();
	337	const auto &to_ref = *to.get_ty ()->as<TyTy::ReferenceType> ();
	338
	339	if (from_ref.is_dyn_object () != to_ref.is_dyn_object ())
	340	{
	341	// this needs to be handled by coercion logic
	342	return TypeCoercionRules::CoercionResult::get_error ();
	343	}
	344
	345	// are the underlying types safely simple castable?
	346	const auto to_underly = to_ref.get_base ();
	347	const auto from_underly = from_ref.get_base ();
	348	auto res = resolve (locus, TyTy::TyWithLocation (from_underly),
	349	TyTy::TyWithLocation (to_underly), false);
	350	if (res.is_error ())
	351	{
	352	// this needs to be handled by coercion logic
	353	return TypeCoercionRules::CoercionResult::get_error ();
	354	}
	355
	356	// mutability must be coerceable
06688fe4 PH	357	TyTy::ReferenceType &f
	358	= static_cast<TyTy::ReferenceType &> (*from.get_ty ());
	359	TyTy::ReferenceType &t
	360	= static_cast<TyTy::ReferenceType &> (*to.get_ty ());
	361
	362	if (TypeCoercionRules::coerceable_mutability (f.mutability (),
	363	t.mutability ()))
	364	{
	365	return TypeCoercionRules::CoercionResult{{}, to.get_ty ()->clone ()};
	366	}
	367	}
	368
	369	return TypeCoercionRules::CoercionResult::get_error ();
	370	}
	371
	372	void
04b29afc PH	373	TypeCastRules::emit_cast_error (location_t locus, TyTy::TyWithLocation from,
04b29afc PH	374	TyTy::TyWithLocation to)
06688fe4	375	{
ffadba42	376	rich_location r (line_table, locus);
06688fe4 PH	377	r.add_range (from.get_locus ());
06688fe4 PH	378	r.add_range (to.get_locus ());
2952785b MM	379	ErrorCode error_code;
	380	std::string error_msg;
	381	switch (to.get_ty ()->get_kind ())
	382	{
	383	case TyTy::TypeKind::BOOL:
	384	error_msg = "cannot cast %qs as %qs";
	385	error_code = ErrorCode::E0054;
	386	break;
	387	case TyTy::TypeKind::CHAR:
	388	error_msg
	389	+= "cannot cast %qs as %qs, only %<u8%> can be cast as %<char%>";
	390	error_code = ErrorCode::E0604;
	391	break;
	392	case TyTy::TypeKind::SLICE:
	393	error_msg = "cast to unsized type: %qs as %qs";
	394	error_code = ErrorCode::E0620;
	395	break;
	396
	397	default:
	398	error_msg = "casting %qs as %qs is invalid";
	399	error_code = ErrorCode::E0606;
	400	break;
	401	}
	402	rust_error_at (r, error_code, error_msg.c_str (),
06688fe4 PH	403	from.get_ty ()->get_name ().c_str (),
	404	to.get_ty ()->get_name ().c_str ());
	405	}
	406
	407	} // namespace Resolver
1b34e40e	408	} // namespace Rust