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add SafeSerializationEventArgs
[mcs.git] / mcs / convert.cs
blobe81383ddc54f372706ce8e3cb003542cd5e01a9c
1 //
2 // conversion.cs: various routines for implementing conversions.
3 //
4 // Authors:
5 // Miguel de Icaza (miguel@ximian.com)
6 // Ravi Pratap (ravi@ximian.com)
7 // Marek Safar (marek.safar@gmail.com)
8 //
9 // Copyright 2001, 2002, 2003 Ximian, Inc.
10 // Copyright 2003-2008 Novell, Inc.
11 //
12
13 using System;
14 using System.Collections.Generic;
15 using System.Diagnostics;
16 using System.Reflection;
17 using System.Reflection.Emit;
18
19 namespace Mono.CSharp {
20
21 //
22 // A container class for all the conversion operations
23 //
24 static class Convert {
25
26 static EmptyExpression MyEmptyExpr;
27 static DoubleHash explicit_conv;
28 static DoubleHash implicit_conv;
29
30 static Convert ()
31 {
32 Reset ();
33 }
34
35 public static void Reset ()
36 {
37 MyEmptyExpr = null;
38 explicit_conv = new DoubleHash (100);
39 implicit_conv = new DoubleHash (100);
40 }
41
42 //
43 // From a one-dimensional array-type S[] to System.Collections.IList<T> and base
44 // interfaces of this interface, provided there is an implicit reference conversion
45 // from S to T.
46 //
47 static bool ArrayToIList (ArrayContainer array, TypeSpec list, bool isExplicit)
48 {
49 if (array.Rank != 1 || !list.IsGeneric)
50 return false;
51
52 var open_version = list.GetDefinition ();
53 if ((open_version != TypeManager.generic_ilist_type) &&
54 (open_version != TypeManager.generic_icollection_type) &&
55 (open_version != TypeManager.generic_ienumerable_type))
56 return false;
57
58 var arg_type = list.TypeArguments[0];
59 if (array.Element == arg_type)
60 return true;
61
62 if (isExplicit)
63 return ExplicitReferenceConversionExists (array.Element, arg_type);
64
65 if (MyEmptyExpr == null)
66 MyEmptyExpr = new EmptyExpression (array.Element);
67 else
68 MyEmptyExpr.SetType (array.Element);
69
70 return ImplicitReferenceConversionExists (MyEmptyExpr, arg_type);
71 }
72
73 static bool IList_To_Array(TypeSpec list, ArrayContainer array)
74 {
75 if (array.Rank != 1 || !list.IsGeneric)
76 return false;
77
78 var open_version = list.GetDefinition ();
79 if ((open_version != TypeManager.generic_ilist_type) &&
80 (open_version != TypeManager.generic_icollection_type) &&
81 (open_version != TypeManager.generic_ienumerable_type))
82 return false;
83
84 var arg_type = list.TypeArguments[0];
85 if (array.Element == arg_type)
86 return true;
87
88 if (MyEmptyExpr == null)
89 MyEmptyExpr = new EmptyExpression (array.Element);
90 else
91 MyEmptyExpr.SetType (array.Element);
92
93 return ImplicitReferenceConversionExists (MyEmptyExpr, arg_type) || ExplicitReferenceConversionExists (array.Element, arg_type);
94 }
95
96 static Expression ImplicitTypeParameterConversion (Expression expr, TypeSpec target_type)
97 {
98 var expr_type = (TypeParameterSpec) expr.Type;
99 //
100 // From T to a type parameter U
101 //
102 var ttype = target_type as TypeParameterSpec;
103 if (ttype != null) {
104 if (expr_type.IsReferenceType && !ttype.IsReferenceType)
105 return new BoxedCast (expr, target_type);
106
107 return new ClassCast (expr, target_type);
108 }
109
110 //
111 // From T to its effective base class C
112 // From T to any base class of C
113 // From T to any interface implemented by C
114 //
115 var base_type = expr_type.GetEffectiveBase ();
116 if (base_type == target_type || TypeManager.IsSubclassOf (base_type, target_type) || base_type.ImplementsInterface (target_type)) {
117 if (expr_type.IsReferenceType)
118 return new ClassCast (expr, target_type);
119
120 return new BoxedCast (expr, target_type);
121 }
122
123 if (target_type.IsInterface && expr_type.IsConvertibleToInterface (target_type)) {
124 if (expr_type.IsReferenceType)
125 return new ClassCast (expr, target_type);
126
127 return new BoxedCast (expr, target_type);
128 }
129
130 return null;
131 }
132
133 static Expression ExplicitTypeParameterConversion (Expression source, TypeSpec source_type, TypeSpec target_type)
134 {
135 var target_tp = target_type as TypeParameterSpec;
136 if (target_tp != null) {
137 if (target_tp.Interfaces != null) {
138 foreach (TypeSpec iface in target_tp.Interfaces) {
139 if (!TypeManager.IsGenericParameter (iface))
140 continue;
141
142 if (TypeManager.IsSubclassOf (source_type, iface))
143 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type, true);
144 }
145 }
146
147 return null;
148 }
149
150 if (target_type.IsInterface)
151 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type, true);
152
153 return null;
154 }
155
156 static Expression ImplicitReferenceConversion (Expression expr, TypeSpec target_type, bool explicit_cast)
157 {
158 TypeSpec expr_type = expr.Type;
159
160 if (expr_type == null && expr.eclass == ExprClass.MethodGroup){
161 // if we are a method group, emit a warning
162
163 expr.Emit (null);
164 }
165
166 if (expr_type == TypeManager.void_type)
167 return null;
168
169 if (expr_type.Kind == MemberKind.TypeParameter)
170 return ImplicitTypeParameterConversion (expr, target_type);
171
172 //
173 // from the null type to any reference-type.
174 //
175 NullLiteral nl = expr as NullLiteral;
176 if (nl != null) {
177 return nl.ConvertImplicitly (null, target_type);
178 }
179
180 if (ImplicitReferenceConversionExists (expr, target_type)) {
181 //
182 // Avoid wrapping implicitly convertible reference type
183 //
184 if (!explicit_cast)
185 return expr;
186
187 return EmptyCast.Create (expr, target_type);
188 }
189
190 return ImplicitBoxingConversion (expr, expr_type, target_type);
191 }
192
193 //
194 // 6.1.6 Implicit reference conversions
195 //
196 public static bool ImplicitReferenceConversionExists (Expression expr, TypeSpec target_type)
197 {
198 if (TypeManager.IsStruct (target_type))
199 return false;
200
201 TypeSpec expr_type = expr.Type;
202
203 // from the null type to any reference-type.
204 if (expr_type == TypeManager.null_type)
205 return target_type != InternalType.AnonymousMethod;
206
207 if (TypeManager.IsGenericParameter (expr_type))
208 return ImplicitTypeParameterConversion (expr, target_type) != null;
209
210 // This code is kind of mirrored inside ImplicitStandardConversionExists
211 // with the small distinction that we only probe there
212 //
213 // Always ensure that the code here and there is in sync
214
215 // from any class-type S to any interface-type T.
216 if (target_type.IsInterface) {
217 if (expr_type.ImplementsInterface (target_type)){
218 return !TypeManager.IsValueType (expr_type);
219 }
220 }
221
222 //
223 // notice that it is possible to write "ValueType v = 1", the ValueType here
224 // is an abstract class, and not really a value type, so we apply the same rules.
225 //
226 if (target_type == TypeManager.object_type || target_type == InternalType.Dynamic) {
227 //
228 // A pointer type cannot be converted to object
229 //
230 if (expr_type.IsPointer)
231 return false;
232
233 if (TypeManager.IsValueType (expr_type))
234 return false;
235
236 if (expr_type.IsClass || expr_type.IsInterface || expr_type == TypeManager.enum_type || expr_type.IsDelegate) {
237 // No mcs internal types are convertible
238 return true; // expr_type.MetaInfo.Module != typeof (Convert).Module;
239 }
240
241 // From anything to dynamic
242 if (target_type == InternalType.Dynamic)
243 return true;
244
245 // From dynamic to object
246 if (expr_type == InternalType.Dynamic)
247 return true;
248
249 return false;
250 } else if (target_type == TypeManager.value_type) {
251 return expr_type == TypeManager.enum_type;
252 } else if (TypeManager.IsSubclassOf (expr_type, target_type)) {
253 //
254 // Special case: enumeration to System.Enum.
255 // System.Enum is not a value type, it is a class, so we need
256 // a boxing conversion
257 //
258 if (target_type == TypeManager.enum_type || TypeManager.IsGenericParameter (expr_type))
259 return false;
260
261 if (TypeManager.IsValueType (expr_type))
262 return false;
263
264 // Array type variance conversion
265 //if (target_type.IsArray != expr_type.IsArray)
266 // return false;
267
268 return true;
269 }
270
271 var expr_type_array = expr_type as ArrayContainer;
272 if (expr_type_array != null) {
273 var target_type_array = target_type as ArrayContainer;
274 // from an array-type S to an array-type of type T
275 if (target_type_array != null && expr_type_array.Rank == target_type_array.Rank) {
276
277 //
278 // Both SE and TE are reference-types
279 //
280 TypeSpec expr_element_type = expr_type_array.Element;
281 if (!TypeManager.IsReferenceType (expr_element_type))
282 return false;
283
284 TypeSpec target_element_type = target_type_array.Element;
285 if (!TypeManager.IsReferenceType (target_element_type))
286 return false;
287
288 if (MyEmptyExpr == null)
289 MyEmptyExpr = new EmptyExpression (expr_element_type);
290 else
291 MyEmptyExpr.SetType (expr_element_type);
292
293 return ImplicitStandardConversionExists (MyEmptyExpr, target_element_type);
294 }
295
296 // from an array-type to System.Array
297 if (target_type == TypeManager.array_type)
298 return true;
299
300 // from an array-type of type T to IList<T>
301 if (ArrayToIList (expr_type_array, target_type, false))
302 return true;
303
304 return false;
305 }
306
307 if (TypeSpecComparer.Variant.IsEqual (expr_type, target_type))
308 return true;
309
310 // from any interface type S to interface-type T.
311 if (expr_type.IsInterface && target_type.IsInterface) {
312 return expr_type.ImplementsInterface (target_type);
313 }
314
315 // from any delegate type to System.Delegate
316 if (target_type == TypeManager.delegate_type &&
317 (expr_type == TypeManager.delegate_type || expr_type.IsDelegate))
318 return true;
319
320 if (TypeManager.IsEqual (expr_type, target_type))
321 return true;
322
323 return false;
324 }
325
326 public static Expression ImplicitBoxingConversion (Expression expr, TypeSpec expr_type, TypeSpec target_type)
327 {
328 //
329 // From any value-type to the type object.
330 //
331 if (target_type == TypeManager.object_type || target_type == InternalType.Dynamic) {
332 //
333 // A pointer type cannot be converted to object
334 //
335 if (expr_type.IsPointer)
336 return null;
337
338 if (!TypeManager.IsValueType (expr_type))
339 return null;
340
341 return expr == null ? EmptyExpression.Null : new BoxedCast (expr, target_type);
342 }
343
344 //
345 // From any value-type to the type System.ValueType.
346 //
347 if (target_type == TypeManager.value_type) {
348 if (!TypeManager.IsValueType (expr_type))
349 return null;
350
351 return expr == null ? EmptyExpression.Null : new BoxedCast (expr, target_type);
352 }
353
354 if (target_type == TypeManager.enum_type) {
355 //
356 // From any enum-type to the type System.Enum.
357 //
358 if (TypeManager.IsEnumType (expr_type))
359 return expr == null ? EmptyExpression.Null : new BoxedCast (expr, target_type);
360 }
361
362 //
363 // From a nullable-type to a reference type, if a boxing conversion exists from
364 // the underlying type to the reference type
365 //
366 if (TypeManager.IsNullableType (expr_type)) {
367 if (!TypeManager.IsReferenceType (target_type))
368 return null;
369
370 var res = ImplicitBoxingConversion (expr, Nullable.NullableInfo.GetUnderlyingType (expr_type), target_type);
371
372 // "cast" underlying type to target type to emit correct InvalidCastException when
373 // underlying hierarchy changes without recompilation
374 if (res != null && expr != null)
375 res = new UnboxCast (res, target_type);
376
377 return res;
378 }
379
380 if (TypeManager.IsSubclassOf (expr_type, target_type)) {
381 //
382 // Don't box same type arguments
383 //
384 if (TypeManager.IsGenericParameter (expr_type) && expr_type != target_type)
385 return expr == null ? EmptyExpression.Null : new BoxedCast (expr, target_type);
386
387 return null;
388 }
389
390 // This code is kind of mirrored inside ImplicitStandardConversionExists
391 // with the small distinction that we only probe there
392 //
393 // Always ensure that the code here and there is in sync
394
395 // from any class-type S to any interface-type T.
396 if (target_type.IsInterface) {
397 if (expr_type.ImplementsInterface (target_type) &&
398 (TypeManager.IsGenericParameter (expr_type) || TypeManager.IsValueType (expr_type))) {
399 return expr == null ? EmptyExpression.Null : new BoxedCast (expr, target_type);
400 }
401 }
402
403 return null;
404 }
405
406 public static Expression ImplicitNulableConversion (ResolveContext ec, Expression expr, TypeSpec target_type)
407 {
408 TypeSpec expr_type = expr.Type;
409
410 //
411 // From null to any nullable type
412 //
413 if (expr_type == TypeManager.null_type)
414 return ec == null ? EmptyExpression.Null : Nullable.LiftedNull.Create (target_type, expr.Location);
415
416 // S -> T?
417 TypeSpec t_el = TypeManager.GetTypeArguments (target_type)[0];
418
419 // S? -> T?
420 if (TypeManager.IsNullableType (expr_type))
421 expr_type = TypeManager.GetTypeArguments (expr_type)[0];
422
423 //
424 // Predefined implicit identity or implicit numeric conversion
425 // has to exist between underlying type S and underlying type T
426 //
427
428 // Handles probing
429 if (ec == null) {
430 if (expr_type == t_el)
431 return EmptyExpression.Null;
432
433 return ImplicitNumericConversion (null, expr_type, t_el);
434 }
435
436 Expression unwrap;
437 if (expr_type != expr.Type)
438 unwrap = Nullable.Unwrap.Create (expr);
439 else
440 unwrap = expr;
441
442 Expression conv = expr_type == t_el ? unwrap : ImplicitNumericConversion (unwrap, expr_type, t_el);
443 if (conv == null)
444 return null;
445
446 if (expr_type != expr.Type)
447 return new Nullable.Lifted (conv, unwrap, target_type).Resolve (ec);
448
449 // Do constant optimization for S -> T?
450 if (unwrap is Constant)
451 conv = ((Constant) unwrap).ConvertImplicitly (ec, t_el);
452
453 return Nullable.Wrap.Create (conv, target_type);
454 }
455
456 /// <summary>
457 /// Implicit Numeric Conversions.
458 ///
459 /// expr is the expression to convert, returns a new expression of type
460 /// target_type or null if an implicit conversion is not possible.
461 /// </summary>
462 public static Expression ImplicitNumericConversion (Expression expr, TypeSpec target_type)
463 {
464 return ImplicitNumericConversion (expr, expr.Type, target_type);
465 }
466
467 static Expression ImplicitNumericConversion (Expression expr, TypeSpec expr_type, TypeSpec target_type)
468 {
469 if (expr_type == TypeManager.sbyte_type){
470 //
471 // From sbyte to short, int, long, float, double, decimal
472 //
473 if (target_type == TypeManager.int32_type)
474 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
475 if (target_type == TypeManager.int64_type)
476 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
477 if (target_type == TypeManager.double_type)
478 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
479 if (target_type == TypeManager.float_type)
480 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
481 if (target_type == TypeManager.short_type)
482 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
483 if (target_type == TypeManager.decimal_type)
484 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
485 } else if (expr_type == TypeManager.byte_type){
486 //
487 // From byte to short, ushort, int, uint, long, ulong, float, double, decimal
488 //
489 if (target_type == TypeManager.int32_type || target_type == TypeManager.uint32_type ||
490 target_type == TypeManager.short_type || target_type == TypeManager.ushort_type)
491 return expr == null ? EmptyExpression.Null : EmptyCast.Create (expr, target_type);
492
493 if (target_type == TypeManager.uint64_type)
494 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
495 if (target_type == TypeManager.int64_type)
496 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
497 if (target_type == TypeManager.float_type)
498 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
499 if (target_type == TypeManager.double_type)
500 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
501 if (target_type == TypeManager.decimal_type)
502 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
503
504 } else if (expr_type == TypeManager.short_type){
505 //
506 // From short to int, long, float, double, decimal
507 //
508 if (target_type == TypeManager.int32_type)
509 return expr == null ? EmptyExpression.Null : EmptyCast.Create (expr, target_type);
510 if (target_type == TypeManager.int64_type)
511 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
512 if (target_type == TypeManager.double_type)
513 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
514 if (target_type == TypeManager.float_type)
515 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
516 if (target_type == TypeManager.decimal_type)
517 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
518
519 } else if (expr_type == TypeManager.ushort_type){
520 //
521 // From ushort to int, uint, long, ulong, float, double, decimal
522 //
523 if (target_type == TypeManager.int32_type || target_type == TypeManager.uint32_type)
524 return expr == null ? EmptyExpression.Null : EmptyCast.Create (expr, target_type);
525
526 if (target_type == TypeManager.uint64_type)
527 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
528 if (target_type == TypeManager.int64_type)
529 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
530 if (target_type == TypeManager.double_type)
531 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
532 if (target_type == TypeManager.float_type)
533 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
534 if (target_type == TypeManager.decimal_type)
535 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
536 } else if (expr_type == TypeManager.int32_type){
537 //
538 // From int to long, float, double, decimal
539 //
540 if (target_type == TypeManager.int64_type)
541 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
542 if (target_type == TypeManager.double_type)
543 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
544 if (target_type == TypeManager.float_type)
545 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
546 if (target_type == TypeManager.decimal_type)
547 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
548 } else if (expr_type == TypeManager.uint32_type){
549 //
550 // From uint to long, ulong, float, double, decimal
551 //
552 if (target_type == TypeManager.int64_type)
553 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
554 if (target_type == TypeManager.uint64_type)
555 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
556 if (target_type == TypeManager.double_type)
557 return expr == null ? EmptyExpression.Null : new OpcodeCast (new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un), target_type, OpCodes.Conv_R8);
558 if (target_type == TypeManager.float_type)
559 return expr == null ? EmptyExpression.Null : new OpcodeCast (new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un), target_type, OpCodes.Conv_R4);
560 if (target_type == TypeManager.decimal_type)
561 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
562 } else if (expr_type == TypeManager.int64_type){
563 //
564 // From long/ulong to float, double
565 //
566 if (target_type == TypeManager.double_type)
567 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
568 if (target_type == TypeManager.float_type)
569 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
570 if (target_type == TypeManager.decimal_type)
571 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
572 } else if (expr_type == TypeManager.uint64_type){
573 //
574 // From ulong to float, double
575 //
576 if (target_type == TypeManager.double_type)
577 return expr == null ? EmptyExpression.Null : new OpcodeCast (new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un), target_type, OpCodes.Conv_R8);
578 if (target_type == TypeManager.float_type)
579 return expr == null ? EmptyExpression.Null : new OpcodeCast (new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un), target_type, OpCodes.Conv_R4);
580 if (target_type == TypeManager.decimal_type)
581 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
582 } else if (expr_type == TypeManager.char_type){
583 //
584 // From char to ushort, int, uint, long, ulong, float, double, decimal
585 //
586 if ((target_type == TypeManager.ushort_type) ||
587 (target_type == TypeManager.int32_type) ||
588 (target_type == TypeManager.uint32_type))
589 return expr == null ? EmptyExpression.Null : EmptyCast.Create (expr, target_type);
590 if (target_type == TypeManager.uint64_type)
591 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
592 if (target_type == TypeManager.int64_type)
593 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
594 if (target_type == TypeManager.float_type)
595 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
596 if (target_type == TypeManager.double_type)
597 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
598 if (target_type == TypeManager.decimal_type)
599 return expr == null ? EmptyExpression.Null : new CastToDecimal (expr);
600 } else if (expr_type == TypeManager.float_type){
601 //
602 // float to double
603 //
604 if (target_type == TypeManager.double_type)
605 return expr == null ? EmptyExpression.Null : new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
606 }
607
608 return null;
609 }
610
611 /// <summary>
612 /// Same as ImplicitStandardConversionExists except that it also looks at
613 /// implicit user defined conversions - needed for overload resolution
614 /// </summary>
615 public static bool ImplicitConversionExists (ResolveContext ec, Expression expr, TypeSpec target_type)
616 {
617 if (ImplicitStandardConversionExists (expr, target_type))
618 return true;
619
620 if (expr.Type == InternalType.AnonymousMethod) {
621 if (!TypeManager.IsDelegateType (target_type) && target_type.GetDefinition () != TypeManager.expression_type)
622 return false;
623
624 AnonymousMethodExpression ame = (AnonymousMethodExpression) expr;
625 return ame.ImplicitStandardConversionExists (ec, target_type);
626 }
627
628 if (expr.eclass == ExprClass.MethodGroup) {
629 if (target_type.IsDelegate && RootContext.Version != LanguageVersion.ISO_1) {
630 MethodGroupExpr mg = expr as MethodGroupExpr;
631 if (mg != null)
632 return DelegateCreation.ImplicitStandardConversionExists (ec, mg, target_type);
633 }
634
635 return false;
636 }
637
638 return ImplicitUserConversion (ec, expr, target_type, Location.Null) != null;
639 }
640
641 /// <summary>
642 /// Determines if a standard implicit conversion exists from
643 /// expr_type to target_type
644 ///
645 /// ec should point to a real EmitContext if expr.Type is TypeManager.anonymous_method_type.
646 /// </summary>
647 public static bool ImplicitStandardConversionExists (Expression expr, TypeSpec target_type)
648 {
649 TypeSpec expr_type = expr.Type;
650
651 if (expr_type == TypeManager.null_type) {
652 NullLiteral nl = expr as NullLiteral;
653 if (nl != null)
654 return nl.ConvertImplicitly (null, target_type) != null;
655 }
656
657 if (expr_type == TypeManager.void_type)
658 return false;
659
660 if (TypeManager.IsEqual (expr_type, target_type))
661 return true;
662
663 if (TypeManager.IsNullableType (target_type)) {
664 return ImplicitNulableConversion (null, expr, target_type) != null;
665 }
666
667 // First numeric conversions
668 if (ImplicitNumericConversion (null, expr_type, target_type) != null)
669 return true;
670
671 if (ImplicitReferenceConversionExists (expr, target_type))
672 return true;
673
674 if (ImplicitBoxingConversion (null, expr_type, target_type) != null)
675 return true;
676
677 //
678 // Implicit Constant Expression Conversions
679 //
680 if (expr is IntConstant){
681 int value = ((IntConstant) expr).Value;
682
683 if (target_type == TypeManager.sbyte_type){
684 if (value >= SByte.MinValue && value <= SByte.MaxValue)
685 return true;
686 } else if (target_type == TypeManager.byte_type){
687 if (value >= 0 && value <= Byte.MaxValue)
688 return true;
689 } else if (target_type == TypeManager.short_type){
690 if (value >= Int16.MinValue && value <= Int16.MaxValue)
691 return true;
692 } else if (target_type == TypeManager.ushort_type){
693 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
694 return true;
695 } else if (target_type == TypeManager.uint32_type){
696 if (value >= 0)
697 return true;
698 } else if (target_type == TypeManager.uint64_type){
699 //
700 // we can optimize this case: a positive int32
701 // always fits on a uint64. But we need an opcode
702 // to do it.
703 //
704 if (value >= 0)
705 return true;
706 }
707
708 if (value == 0 && target_type.IsEnum)
709 return true;
710 }
711
712 if (expr is LongConstant && target_type == TypeManager.uint64_type){
713 //
714 // Try the implicit constant expression conversion
715 // from long to ulong, instead of a nice routine,
716 // we just inline it
717 //
718 long v = ((LongConstant) expr).Value;
719 if (v >= 0)
720 return true;
721 }
722
723 //
724 // If `expr_type' implements `target_type' (which is an iface)
725 // see TryImplicitIntConversion
726 //
727 if (target_type.IsInterface && expr_type.ImplementsInterface (target_type))
728 return true;
729
730 if (target_type == TypeManager.void_ptr_type && expr_type.IsPointer)
731 return true;
732
733 // Conversion from __arglist to System.ArgIterator
734 if (expr_type == InternalType.Arglist)
735 return target_type == TypeManager.arg_iterator_type;
736
737 return false;
738 }
739
740 /// <summary>
741 /// Finds "most encompassed type" according to the spec (13.4.2)
742 /// amongst the methods in the MethodGroupExpr
743 /// </summary>
744 public static TypeSpec FindMostEncompassedType (IEnumerable<TypeSpec> types)
745 {
746 TypeSpec best = null;
747 EmptyExpression expr = EmptyExpression.Grab ();
748
749 foreach (TypeSpec t in types) {
750 if (best == null) {
751 best = t;
752 continue;
753 }
754
755 expr.SetType (t);
756 if (ImplicitStandardConversionExists (expr, best))
757 best = t;
758 }
759
760 expr.SetType (best);
761 foreach (TypeSpec t in types) {
762 if (best == t)
763 continue;
764 if (!ImplicitStandardConversionExists (expr, t)) {
765 best = null;
766 break;
767 }
768 }
769
770 EmptyExpression.Release (expr);
771
772 return best;
773 }
774
775 /// <summary>
776 /// Finds "most encompassing type" according to the spec (13.4.2)
777 /// amongst the types in the given set
778 /// </summary>
779 static TypeSpec FindMostEncompassingType (IList<TypeSpec> types)
780 {
781 TypeSpec best = null;
782
783 if (types.Count == 0)
784 return null;
785
786 if (types.Count == 1)
787 return types [0];
788
789 EmptyExpression expr = EmptyExpression.Grab ();
790
791 foreach (TypeSpec t in types) {
792 if (best == null) {
793 best = t;
794 continue;
795 }
796
797 expr.SetType (best);
798 if (ImplicitStandardConversionExists (expr, t))
799 best = t;
800 }
801
802 foreach (TypeSpec t in types) {
803 if (best == t)
804 continue;
805 expr.SetType (t);
806 if (!ImplicitStandardConversionExists (expr, best)) {
807 best = null;
808 break;
809 }
810 }
811
812 EmptyExpression.Release (expr);
813
814 return best;
815 }
816
817 /// <summary>
818 /// Finds the most specific source Sx according to the rules of the spec (13.4.4)
819 /// by making use of FindMostEncomp* methods. Applies the correct rules separately
820 /// for explicit and implicit conversion operators.
821 /// </summary>
822 static public TypeSpec FindMostSpecificSource (IList<MethodSpec> list,
823 Expression source, bool apply_explicit_conv_rules)
824 {
825 var src_types_set = new List<TypeSpec> ();
826
827 //
828 // If any operator converts from S then Sx = S
829 //
830 TypeSpec source_type = source.Type;
831 foreach (var mb in list){
832 TypeSpec param_type = mb.Parameters.Types [0];
833
834 if (param_type == source_type)
835 return param_type;
836
837 src_types_set.Add (param_type);
838 }
839
840 //
841 // Explicit Conv rules
842 //
843 if (apply_explicit_conv_rules) {
844 var candidate_set = new List<TypeSpec> ();
845
846 foreach (TypeSpec param_type in src_types_set){
847 if (ImplicitStandardConversionExists (source, param_type))
848 candidate_set.Add (param_type);
849 }
850
851 if (candidate_set.Count != 0)
852 return FindMostEncompassedType (candidate_set);
853 }
854
855 //
856 // Final case
857 //
858 if (apply_explicit_conv_rules)
859 return FindMostEncompassingType (src_types_set);
860 else
861 return FindMostEncompassedType (src_types_set);
862 }
863
864 /// <summary>
865 /// Finds the most specific target Tx according to section 13.4.4
866 /// </summary>
867 static public TypeSpec FindMostSpecificTarget (IList<MethodSpec> list,
868 TypeSpec target, bool apply_explicit_conv_rules)
869 {
870 var tgt_types_set = new List<TypeSpec> ();
871
872 //
873 // If any operator converts to T then Tx = T
874 //
875 foreach (var mi in list){
876 TypeSpec ret_type = mi.ReturnType;
877 if (ret_type == target)
878 return ret_type;
879
880 tgt_types_set.Add (ret_type);
881 }
882
883 //
884 // Explicit conv rules
885 //
886 if (apply_explicit_conv_rules) {
887 var candidate_set = new List<TypeSpec> ();
888
889 EmptyExpression expr = EmptyExpression.Grab ();
890
891 foreach (TypeSpec ret_type in tgt_types_set){
892 expr.SetType (ret_type);
893
894 if (ImplicitStandardConversionExists (expr, target))
895 candidate_set.Add (ret_type);
896 }
897
898 EmptyExpression.Release (expr);
899
900 if (candidate_set.Count != 0)
901 return FindMostEncompassingType (candidate_set);
902 }
903
904 //
905 // Okay, final case !
906 //
907 if (apply_explicit_conv_rules)
908 return FindMostEncompassedType (tgt_types_set);
909 else
910 return FindMostEncompassingType (tgt_types_set);
911 }
912
913 /// <summary>
914 /// User-defined Implicit conversions
915 /// </summary>
916 static public Expression ImplicitUserConversion (ResolveContext ec, Expression source,
917 TypeSpec target, Location loc)
918 {
919 return UserDefinedConversion (ec, source, target, loc, false, true);
920 }
921
922 /// <summary>
923 /// User-defined Explicit conversions
924 /// </summary>
925 static Expression ExplicitUserConversion (ResolveContext ec, Expression source,
926 TypeSpec target, Location loc)
927 {
928 return UserDefinedConversion (ec, source, target, loc, true, true);
929 }
930
931 static void AddConversionOperators (List<MethodSpec> list,
932 Expression source, TypeSpec target_type,
933 bool look_for_explicit,
934 MethodGroupExpr mg)
935 {
936 if (mg == null)
937 return;
938
939 TypeSpec source_type = source.Type;
940 EmptyExpression expr = EmptyExpression.Grab ();
941
942 //
943 // LAMESPEC: Undocumented IntPtr/UIntPtr conversions
944 // IntPtr -> uint uses int
945 // UIntPtr -> long uses ulong
946 //
947 if (source_type == TypeManager.intptr_type) {
948 if (target_type == TypeManager.uint32_type)
949 target_type = TypeManager.int32_type;
950 } else if (source_type == TypeManager.uintptr_type) {
951 if (target_type == TypeManager.int64_type)
952 target_type = TypeManager.uint64_type;
953 }
954
955 foreach (MethodSpec m in mg.Methods) {
956 AParametersCollection pd = m.Parameters;
957 TypeSpec return_type = m.ReturnType;
958 TypeSpec arg_type = pd.Types [0];
959
960 if (source_type != arg_type) {
961 if (!ImplicitStandardConversionExists (source, arg_type)) {
962 if (!look_for_explicit)
963 continue;
964 expr.SetType (arg_type);
965 if (!ImplicitStandardConversionExists (expr, source_type))
966 continue;
967 }
968 }
969
970 if (target_type != return_type) {
971 expr.SetType (return_type);
972 if (!ImplicitStandardConversionExists (expr, target_type)) {
973 if (!look_for_explicit)
974 continue;
975 expr.SetType (target_type);
976 if (!ImplicitStandardConversionExists (expr, return_type))
977 continue;
978 }
979 }
980
981 // See LAMESPEC: Exclude IntPtr -> int conversion
982 if (source_type == TypeManager.uintptr_type && return_type == TypeManager.uint32_type)
983 continue;
984
985 list.Add (m);
986 }
987
988 EmptyExpression.Release (expr);
989 }
990
991 /// <summary>
992 /// Compute the user-defined conversion operator from source_type to target_type.
993 /// `look_for_explicit' controls whether we should also include the list of explicit operators
994 /// </summary>
995 static MethodSpec GetConversionOperator (CompilerContext ctx, TypeSpec container_type, Expression source, TypeSpec target_type, bool look_for_explicit)
996 {
997 var ops = new List<MethodSpec> (4);
998
999 TypeSpec source_type = source.Type;
1000
1001 if (source_type != TypeManager.decimal_type) {
1002 AddConversionOperators (ops, source, target_type, look_for_explicit,
1003 Expression.MethodLookup (ctx, container_type, source_type, MemberKind.Operator, "op_Implicit", 0, Location.Null));
1004 if (look_for_explicit) {
1005 AddConversionOperators (ops, source, target_type, look_for_explicit,
1006 Expression.MethodLookup (ctx,
1007 container_type, source_type, MemberKind.Operator, "op_Explicit", 0, Location.Null));
1008 }
1009 }
1010
1011 if (target_type != TypeManager.decimal_type) {
1012 AddConversionOperators (ops, source, target_type, look_for_explicit,
1013 Expression.MethodLookup (ctx, container_type, target_type, MemberKind.Operator, "op_Implicit", 0, Location.Null));
1014 if (look_for_explicit) {
1015 AddConversionOperators (ops, source, target_type, look_for_explicit,
1016 Expression.MethodLookup (ctx,
1017 container_type, target_type, MemberKind.Operator, "op_Explicit", 0, Location.Null));
1018 }
1019 }
1020
1021 if (ops.Count == 0)
1022 return null;
1023
1024 TypeSpec most_specific_source = FindMostSpecificSource (ops, source, look_for_explicit);
1025 if (most_specific_source == null)
1026 return null;
1027
1028 TypeSpec most_specific_target = FindMostSpecificTarget (ops, target_type, look_for_explicit);
1029 if (most_specific_target == null)
1030 return null;
1031
1032 MethodSpec method = null;
1033
1034 foreach (var m in ops) {
1035 if (m.ReturnType != most_specific_target)
1036 continue;
1037 if (m.Parameters.Types [0] != most_specific_source)
1038 continue;
1039 // Ambiguous: more than one conversion operator satisfies the signature.
1040 if (method != null)
1041 return null;
1042 method = m;
1043 }
1044
1045 return method;
1046 }
1047
1048 /// <summary>
1049 /// User-defined conversions
1050 /// </summary>
1051 public static Expression UserDefinedConversion (ResolveContext ec, Expression source,
1052 TypeSpec target, Location loc,
1053 bool look_for_explicit, bool return_convert)
1054 {
1055 TypeSpec source_type = source.Type;
1056 MethodSpec method = null;
1057 Expression expr = null;
1058
1059 object o;
1060 DoubleHash hash;
1061 if (look_for_explicit) {
1062 hash = explicit_conv;
1063 } else {
1064 // Implicit user operators cannot convert to interfaces
1065 if (target.IsInterface)
1066 return null;
1067
1068 hash = implicit_conv;
1069 }
1070
1071 if (!(source is Constant) && hash.Lookup (source_type, target, out o)) {
1072 method = (MethodSpec) o;
1073 } else {
1074 if (source_type == InternalType.Dynamic)
1075 return null;
1076
1077 method = GetConversionOperator (ec.Compiler, null, source, target, look_for_explicit);
1078 }
1079
1080 if (method != null) {
1081 TypeSpec most_specific_source = method.Parameters.Types[0];
1082
1083 //
1084 // This will do the conversion to the best match that we
1085 // found. Now we need to perform an implict standard conversion
1086 // if the best match was not the type that we were requested
1087 // by target.
1088 //
1089 if (look_for_explicit) {
1090 ReportPrinter temp = new SessionReportPrinter ();
1091 ReportPrinter prev = ec.Report.SetPrinter (temp);
1092
1093 expr = ExplicitConversionStandard (ec, source, most_specific_source, loc);
1094
1095 ec.Report.SetPrinter (prev);
1096 if (temp.ErrorsCount != 0)
1097 expr = null;
1098 } else {
1099 if (ImplicitStandardConversionExists (source, most_specific_source))
1100 expr = ImplicitConversionStandard (ec, source, most_specific_source, loc);
1101 else
1102 expr = null;
1103 }
1104 }
1105
1106 if (expr == null) {
1107 bool nullable = false;
1108
1109 if (TypeManager.IsNullableType (source_type)) {
1110 source = Nullable.Unwrap.Create (source);
1111 nullable = true;
1112 }
1113
1114 TypeSpec target_underlying;
1115 if (TypeManager.IsNullableType (target)) {
1116 target_underlying = TypeManager.GetTypeArguments (target)[0];
1117 nullable = true;
1118 } else {
1119 // No implicit conversion S? -> T for non-reference type T
1120 if (!look_for_explicit && !TypeManager.IsReferenceType (target))
1121 nullable = false;
1122
1123 target_underlying = target;
1124 }
1125
1126 if (nullable) {
1127 expr = UserDefinedConversion (ec, source, target_underlying, loc, look_for_explicit, return_convert);
1128
1129 // Do result expression lifting only when it's needed
1130 if (expr != null && (!look_for_explicit || TypeManager.IsReferenceType (target)))
1131 expr = new Nullable.Lifted (expr, source, target).Resolve (ec);
1132
1133 return expr;
1134 }
1135 } else {
1136 expr = new UserCast (method, expr, loc).Resolve (ec);
1137
1138 if (return_convert && !TypeManager.IsEqual (expr.Type, target)) {
1139 if (look_for_explicit) {
1140 expr = ExplicitConversionStandard (ec, expr, target, loc);
1141 } else {
1142 expr = ImplicitConversionStandard (ec, expr, target, loc);
1143 }
1144 }
1145 }
1146
1147 if (!(source is Constant))
1148 hash.Insert (source_type, target, method);
1149
1150 return expr;
1151 }
1152
1153 /// <summary>
1154 /// Converts implicitly the resolved expression `expr' into the
1155 /// `target_type'. It returns a new expression that can be used
1156 /// in a context that expects a `target_type'.
1157 /// </summary>
1158 static public Expression ImplicitConversion (ResolveContext ec, Expression expr,
1159 TypeSpec target_type, Location loc)
1160 {
1161 Expression e;
1162
1163 if (target_type == null)
1164 throw new Exception ("Target type is null");
1165
1166 e = ImplicitConversionStandard (ec, expr, target_type, loc);
1167 if (e != null)
1168 return e;
1169
1170 e = ImplicitUserConversion (ec, expr, target_type, loc);
1171 if (e != null)
1172 return e;
1173
1174 return null;
1175 }
1176
1177
1178 /// <summary>
1179 /// Attempts to apply the `Standard Implicit
1180 /// Conversion' rules to the expression `expr' into
1181 /// the `target_type'. It returns a new expression
1182 /// that can be used in a context that expects a
1183 /// `target_type'.
1184 ///
1185 /// This is different from `ImplicitConversion' in that the
1186 /// user defined implicit conversions are excluded.
1187 /// </summary>
1188 static public Expression ImplicitConversionStandard (ResolveContext ec, Expression expr,
1189 TypeSpec target_type, Location loc)
1190 {
1191 return ImplicitConversionStandard (ec, expr, target_type, loc, false);
1192 }
1193
1194 static Expression ImplicitConversionStandard (ResolveContext ec, Expression expr, TypeSpec target_type, Location loc, bool explicit_cast)
1195 {
1196 if (expr.eclass == ExprClass.MethodGroup){
1197 if (!TypeManager.IsDelegateType (target_type)){
1198 return null;
1199 }
1200
1201 //
1202 // Only allow anonymous method conversions on post ISO_1
1203 //
1204 if (RootContext.Version != LanguageVersion.ISO_1){
1205 MethodGroupExpr mg = expr as MethodGroupExpr;
1206 if (mg != null)
1207 return ImplicitDelegateCreation.Create (
1208 ec, mg, target_type, loc);
1209 }
1210 }
1211
1212 TypeSpec expr_type = expr.Type;
1213 Expression e;
1214
1215 if (expr_type.Equals (target_type)) {
1216 if (expr_type != TypeManager.null_type && expr_type != InternalType.AnonymousMethod)
1217 return expr;
1218 return null;
1219 }
1220
1221 if (TypeSpecComparer.Variant.IsEqual (expr_type, target_type)) {
1222 return expr;
1223 }
1224
1225 if (TypeManager.IsNullableType (target_type))
1226 return ImplicitNulableConversion (ec, expr, target_type);
1227
1228 //
1229 // Attempt to do the implicit constant expression conversions
1230 //
1231 Constant c = expr as Constant;
1232 if (c != null) {
1233 try {
1234 c = c.ConvertImplicitly (ec, target_type);
1235 } catch {
1236 Console.WriteLine ("Conversion error happened in line {0}", loc);
1237 throw;
1238 }
1239 if (c != null)
1240 return c;
1241 }
1242
1243 e = ImplicitNumericConversion (expr, expr_type, target_type);
1244 if (e != null)
1245 return e;
1246
1247 e = ImplicitReferenceConversion (expr, target_type, explicit_cast);
1248 if (e != null)
1249 return e;
1250
1251 if (expr is IntConstant && TypeManager.IsEnumType (target_type)){
1252 Constant i = (Constant) expr;
1253 //
1254 // LAMESPEC: Conversion from any 0 constant is allowed
1255 //
1256 // An implicit enumeration conversion permits the decimal-integer-literal 0
1257 // to be converted to any enum-type and to any nullable-type whose underlying
1258 // type is an enum-type
1259 //
1260 if (i.IsDefaultValue)
1261 return new EnumConstant (i, target_type).Resolve (ec);
1262 }
1263
1264 if (ec.IsUnsafe) {
1265 if (expr_type.IsPointer){
1266 if (target_type == TypeManager.void_ptr_type)
1267 return EmptyCast.Create (expr, target_type);
1268
1269 //
1270 // yep, comparing pointer types cant be done with
1271 // t1 == t2, we have to compare their element types.
1272 //
1273 if (target_type.IsPointer){
1274 if (TypeManager.GetElementType(target_type) == TypeManager.GetElementType(expr_type))
1275 return expr;
1276
1277 //return null;
1278 }
1279 }
1280
1281 if (expr_type == TypeManager.null_type && target_type.IsPointer)
1282 return EmptyCast.Create (new NullPointer (loc), target_type);
1283 }
1284
1285 if (expr_type == InternalType.AnonymousMethod){
1286 AnonymousMethodExpression ame = (AnonymousMethodExpression) expr;
1287 Expression am = ame.Compatible (ec, target_type);
1288 if (am != null)
1289 return am.Resolve (ec);
1290 }
1291
1292 if (expr_type == InternalType.Arglist && target_type == TypeManager.arg_iterator_type)
1293 return expr;
1294
1295 return null;
1296 }
1297
1298 /// <summary>
1299 /// Attempts to implicitly convert `source' into `target_type', using
1300 /// ImplicitConversion. If there is no implicit conversion, then
1301 /// an error is signaled
1302 /// </summary>
1303 static public Expression ImplicitConversionRequired (ResolveContext ec, Expression source,
1304 TypeSpec target_type, Location loc)
1305 {
1306 Expression e = ImplicitConversion (ec, source, target_type, loc);
1307 if (e != null)
1308 return e;
1309
1310 if (source.Type == InternalType.Dynamic) {
1311 Arguments args = new Arguments (1);
1312 args.Add (new Argument (source));
1313 return new DynamicConversion (target_type, 0, args, loc).Resolve (ec);
1314 }
1315
1316 source.Error_ValueCannotBeConverted (ec, loc, target_type, false);
1317 return null;
1318 }
1319
1320 /// <summary>
1321 /// Performs the explicit numeric conversions
1322 ///
1323 /// There are a few conversions that are not part of the C# standard,
1324 /// they were interim hacks in the C# compiler that were supposed to
1325 /// become explicit operators in the UIntPtr class and IntPtr class,
1326 /// but for historical reasons it did not happen, so the C# compiler
1327 /// ended up with these special hacks.
1328 ///
1329 /// See bug 59800 for details.
1330 ///
1331 /// The conversion are:
1332 /// UIntPtr->SByte
1333 /// UIntPtr->Int16
1334 /// UIntPtr->Int32
1335 /// IntPtr->UInt64
1336 /// UInt64->IntPtr
1337 /// SByte->UIntPtr
1338 /// Int16->UIntPtr
1339 ///
1340 /// </summary>
1341 public static Expression ExplicitNumericConversion (Expression expr, TypeSpec target_type)
1342 {
1343 TypeSpec expr_type = expr.Type;
1344 TypeSpec real_target_type = target_type;
1345
1346 if (expr_type == TypeManager.sbyte_type){
1347 //
1348 // From sbyte to byte, ushort, uint, ulong, char, uintptr
1349 //
1350 if (real_target_type == TypeManager.byte_type)
1351 return new ConvCast (expr, target_type, ConvCast.Mode.I1_U1);
1352 if (real_target_type == TypeManager.ushort_type)
1353 return new ConvCast (expr, target_type, ConvCast.Mode.I1_U2);
1354 if (real_target_type == TypeManager.uint32_type)
1355 return new ConvCast (expr, target_type, ConvCast.Mode.I1_U4);
1356 if (real_target_type == TypeManager.uint64_type)
1357 return new ConvCast (expr, target_type, ConvCast.Mode.I1_U8);
1358 if (real_target_type == TypeManager.char_type)
1359 return new ConvCast (expr, target_type, ConvCast.Mode.I1_CH);
1360
1361 // One of the built-in conversions that belonged in the class library
1362 if (real_target_type == TypeManager.uintptr_type){
1363 Expression u8e = new ConvCast (expr, TypeManager.uint64_type, ConvCast.Mode.I1_U8);
1364
1365 return new OperatorCast (u8e, TypeManager.uintptr_type, true);
1366 }
1367 } else if (expr_type == TypeManager.byte_type){
1368 //
1369 // From byte to sbyte and char
1370 //
1371 if (real_target_type == TypeManager.sbyte_type)
1372 return new ConvCast (expr, target_type, ConvCast.Mode.U1_I1);
1373 if (real_target_type == TypeManager.char_type)
1374 return new ConvCast (expr, target_type, ConvCast.Mode.U1_CH);
1375 } else if (expr_type == TypeManager.short_type){
1376 //
1377 // From short to sbyte, byte, ushort, uint, ulong, char, uintptr
1378 //
1379 if (real_target_type == TypeManager.sbyte_type)
1380 return new ConvCast (expr, target_type, ConvCast.Mode.I2_I1);
1381 if (real_target_type == TypeManager.byte_type)
1382 return new ConvCast (expr, target_type, ConvCast.Mode.I2_U1);
1383 if (real_target_type == TypeManager.ushort_type)
1384 return new ConvCast (expr, target_type, ConvCast.Mode.I2_U2);
1385 if (real_target_type == TypeManager.uint32_type)
1386 return new ConvCast (expr, target_type, ConvCast.Mode.I2_U4);
1387 if (real_target_type == TypeManager.uint64_type)
1388 return new ConvCast (expr, target_type, ConvCast.Mode.I2_U8);
1389 if (real_target_type == TypeManager.char_type)
1390 return new ConvCast (expr, target_type, ConvCast.Mode.I2_CH);
1391
1392 // One of the built-in conversions that belonged in the class library
1393 if (real_target_type == TypeManager.uintptr_type){
1394 Expression u8e = new ConvCast (expr, TypeManager.uint64_type, ConvCast.Mode.I2_U8);
1395
1396 return new OperatorCast (u8e, TypeManager.uintptr_type, true);
1397 }
1398 } else if (expr_type == TypeManager.ushort_type){
1399 //
1400 // From ushort to sbyte, byte, short, char
1401 //
1402 if (real_target_type == TypeManager.sbyte_type)
1403 return new ConvCast (expr, target_type, ConvCast.Mode.U2_I1);
1404 if (real_target_type == TypeManager.byte_type)
1405 return new ConvCast (expr, target_type, ConvCast.Mode.U2_U1);
1406 if (real_target_type == TypeManager.short_type)
1407 return new ConvCast (expr, target_type, ConvCast.Mode.U2_I2);
1408 if (real_target_type == TypeManager.char_type)
1409 return new ConvCast (expr, target_type, ConvCast.Mode.U2_CH);
1410 } else if (expr_type == TypeManager.int32_type){
1411 //
1412 // From int to sbyte, byte, short, ushort, uint, ulong, char, uintptr
1413 //
1414 if (real_target_type == TypeManager.sbyte_type)
1415 return new ConvCast (expr, target_type, ConvCast.Mode.I4_I1);
1416 if (real_target_type == TypeManager.byte_type)
1417 return new ConvCast (expr, target_type, ConvCast.Mode.I4_U1);
1418 if (real_target_type == TypeManager.short_type)
1419 return new ConvCast (expr, target_type, ConvCast.Mode.I4_I2);
1420 if (real_target_type == TypeManager.ushort_type)
1421 return new ConvCast (expr, target_type, ConvCast.Mode.I4_U2);
1422 if (real_target_type == TypeManager.uint32_type)
1423 return new ConvCast (expr, target_type, ConvCast.Mode.I4_U4);
1424 if (real_target_type == TypeManager.uint64_type)
1425 return new ConvCast (expr, target_type, ConvCast.Mode.I4_U8);
1426 if (real_target_type == TypeManager.char_type)
1427 return new ConvCast (expr, target_type, ConvCast.Mode.I4_CH);
1428
1429 // One of the built-in conversions that belonged in the class library
1430 if (real_target_type == TypeManager.uintptr_type){
1431 Expression u8e = new ConvCast (expr, TypeManager.uint64_type, ConvCast.Mode.I2_U8);
1432
1433 return new OperatorCast (u8e, TypeManager.uintptr_type, true);
1434 }
1435 } else if (expr_type == TypeManager.uint32_type){
1436 //
1437 // From uint to sbyte, byte, short, ushort, int, char
1438 //
1439 if (real_target_type == TypeManager.sbyte_type)
1440 return new ConvCast (expr, target_type, ConvCast.Mode.U4_I1);
1441 if (real_target_type == TypeManager.byte_type)
1442 return new ConvCast (expr, target_type, ConvCast.Mode.U4_U1);
1443 if (real_target_type == TypeManager.short_type)
1444 return new ConvCast (expr, target_type, ConvCast.Mode.U4_I2);
1445 if (real_target_type == TypeManager.ushort_type)
1446 return new ConvCast (expr, target_type, ConvCast.Mode.U4_U2);
1447 if (real_target_type == TypeManager.int32_type)
1448 return new ConvCast (expr, target_type, ConvCast.Mode.U4_I4);
1449 if (real_target_type == TypeManager.char_type)
1450 return new ConvCast (expr, target_type, ConvCast.Mode.U4_CH);
1451 } else if (expr_type == TypeManager.int64_type){
1452 //
1453 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
1454 //
1455 if (real_target_type == TypeManager.sbyte_type)
1456 return new ConvCast (expr, target_type, ConvCast.Mode.I8_I1);
1457 if (real_target_type == TypeManager.byte_type)
1458 return new ConvCast (expr, target_type, ConvCast.Mode.I8_U1);
1459 if (real_target_type == TypeManager.short_type)
1460 return new ConvCast (expr, target_type, ConvCast.Mode.I8_I2);
1461 if (real_target_type == TypeManager.ushort_type)
1462 return new ConvCast (expr, target_type, ConvCast.Mode.I8_U2);
1463 if (real_target_type == TypeManager.int32_type)
1464 return new ConvCast (expr, target_type, ConvCast.Mode.I8_I4);
1465 if (real_target_type == TypeManager.uint32_type)
1466 return new ConvCast (expr, target_type, ConvCast.Mode.I8_U4);
1467 if (real_target_type == TypeManager.uint64_type)
1468 return new ConvCast (expr, target_type, ConvCast.Mode.I8_U8);
1469 if (real_target_type == TypeManager.char_type)
1470 return new ConvCast (expr, target_type, ConvCast.Mode.I8_CH);
1471 } else if (expr_type == TypeManager.uint64_type){
1472 //
1473 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
1474 //
1475 if (real_target_type == TypeManager.sbyte_type)
1476 return new ConvCast (expr, target_type, ConvCast.Mode.U8_I1);
1477 if (real_target_type == TypeManager.byte_type)
1478 return new ConvCast (expr, target_type, ConvCast.Mode.U8_U1);
1479 if (real_target_type == TypeManager.short_type)
1480 return new ConvCast (expr, target_type, ConvCast.Mode.U8_I2);
1481 if (real_target_type == TypeManager.ushort_type)
1482 return new ConvCast (expr, target_type, ConvCast.Mode.U8_U2);
1483 if (real_target_type == TypeManager.int32_type)
1484 return new ConvCast (expr, target_type, ConvCast.Mode.U8_I4);
1485 if (real_target_type == TypeManager.uint32_type)
1486 return new ConvCast (expr, target_type, ConvCast.Mode.U8_U4);
1487 if (real_target_type == TypeManager.int64_type)
1488 return new ConvCast (expr, target_type, ConvCast.Mode.U8_I8);
1489 if (real_target_type == TypeManager.char_type)
1490 return new ConvCast (expr, target_type, ConvCast.Mode.U8_CH);
1491
1492 // One of the built-in conversions that belonged in the class library
1493 if (real_target_type == TypeManager.intptr_type){
1494 return new OperatorCast (EmptyCast.Create (expr, TypeManager.int64_type),
1495 TypeManager.intptr_type, true);
1496 }
1497 } else if (expr_type == TypeManager.char_type){
1498 //
1499 // From char to sbyte, byte, short
1500 //
1501 if (real_target_type == TypeManager.sbyte_type)
1502 return new ConvCast (expr, target_type, ConvCast.Mode.CH_I1);
1503 if (real_target_type == TypeManager.byte_type)
1504 return new ConvCast (expr, target_type, ConvCast.Mode.CH_U1);
1505 if (real_target_type == TypeManager.short_type)
1506 return new ConvCast (expr, target_type, ConvCast.Mode.CH_I2);
1507 } else if (expr_type == TypeManager.float_type){
1508 //
1509 // From float to sbyte, byte, short,
1510 // ushort, int, uint, long, ulong, char
1511 // or decimal
1512 //
1513 if (real_target_type == TypeManager.sbyte_type)
1514 return new ConvCast (expr, target_type, ConvCast.Mode.R4_I1);
1515 if (real_target_type == TypeManager.byte_type)
1516 return new ConvCast (expr, target_type, ConvCast.Mode.R4_U1);
1517 if (real_target_type == TypeManager.short_type)
1518 return new ConvCast (expr, target_type, ConvCast.Mode.R4_I2);
1519 if (real_target_type == TypeManager.ushort_type)
1520 return new ConvCast (expr, target_type, ConvCast.Mode.R4_U2);
1521 if (real_target_type == TypeManager.int32_type)
1522 return new ConvCast (expr, target_type, ConvCast.Mode.R4_I4);
1523 if (real_target_type == TypeManager.uint32_type)
1524 return new ConvCast (expr, target_type, ConvCast.Mode.R4_U4);
1525 if (real_target_type == TypeManager.int64_type)
1526 return new ConvCast (expr, target_type, ConvCast.Mode.R4_I8);
1527 if (real_target_type == TypeManager.uint64_type)
1528 return new ConvCast (expr, target_type, ConvCast.Mode.R4_U8);
1529 if (real_target_type == TypeManager.char_type)
1530 return new ConvCast (expr, target_type, ConvCast.Mode.R4_CH);
1531 if (real_target_type == TypeManager.decimal_type)
1532 return new CastToDecimal (expr, true);
1533 } else if (expr_type == TypeManager.double_type){
1534 //
1535 // From double to sbyte, byte, short,
1536 // ushort, int, uint, long, ulong,
1537 // char, float or decimal
1538 //
1539 if (real_target_type == TypeManager.sbyte_type)
1540 return new ConvCast (expr, target_type, ConvCast.Mode.R8_I1);
1541 if (real_target_type == TypeManager.byte_type)
1542 return new ConvCast (expr, target_type, ConvCast.Mode.R8_U1);
1543 if (real_target_type == TypeManager.short_type)
1544 return new ConvCast (expr, target_type, ConvCast.Mode.R8_I2);
1545 if (real_target_type == TypeManager.ushort_type)
1546 return new ConvCast (expr, target_type, ConvCast.Mode.R8_U2);
1547 if (real_target_type == TypeManager.int32_type)
1548 return new ConvCast (expr, target_type, ConvCast.Mode.R8_I4);
1549 if (real_target_type == TypeManager.uint32_type)
1550 return new ConvCast (expr, target_type, ConvCast.Mode.R8_U4);
1551 if (real_target_type == TypeManager.int64_type)
1552 return new ConvCast (expr, target_type, ConvCast.Mode.R8_I8);
1553 if (real_target_type == TypeManager.uint64_type)
1554 return new ConvCast (expr, target_type, ConvCast.Mode.R8_U8);
1555 if (real_target_type == TypeManager.char_type)
1556 return new ConvCast (expr, target_type, ConvCast.Mode.R8_CH);
1557 if (real_target_type == TypeManager.float_type)
1558 return new ConvCast (expr, target_type, ConvCast.Mode.R8_R4);
1559 if (real_target_type == TypeManager.decimal_type)
1560 return new CastToDecimal (expr, true);
1561 } else if (expr_type == TypeManager.uintptr_type){
1562 //
1563 // Various built-in conversions that belonged in the class library
1564 //
1565 // from uintptr to sbyte, short, int32
1566 //
1567 if (real_target_type == TypeManager.sbyte_type){
1568 Expression uint32e = new OperatorCast (expr, TypeManager.uint32_type, true);
1569 return new ConvCast (uint32e, TypeManager.sbyte_type, ConvCast.Mode.U4_I1);
1570 }
1571 if (real_target_type == TypeManager.short_type){
1572 Expression uint32e = new OperatorCast (expr, TypeManager.uint32_type, true);
1573 return new ConvCast (uint32e, TypeManager.sbyte_type, ConvCast.Mode.U4_I2);
1574 }
1575 if (real_target_type == TypeManager.int32_type){
1576 return EmptyCast.Create (new OperatorCast (expr, TypeManager.uint32_type, true),
1577 TypeManager.int32_type);
1578 }
1579 } else if (expr_type == TypeManager.intptr_type){
1580 if (real_target_type == TypeManager.uint64_type){
1581 return EmptyCast.Create (new OperatorCast (expr, TypeManager.int64_type, true),
1582 TypeManager.uint64_type);
1583 }
1584 } else if (expr_type == TypeManager.decimal_type) {
1585 return new CastFromDecimal (expr, target_type).Resolve ();
1586 }
1587 return null;
1588 }
1589
1590 /// <summary>
1591 /// Returns whether an explicit reference conversion can be performed
1592 /// from source_type to target_type
1593 /// </summary>
1594 public static bool ExplicitReferenceConversionExists (TypeSpec source_type, TypeSpec target_type)
1595 {
1596 Expression e = ExplicitReferenceConversion (null, source_type, target_type);
1597 if (e == null)
1598 return false;
1599
1600 if (e == EmptyExpression.Null)
1601 return true;
1602
1603 throw new InternalErrorException ("Invalid probing conversion result");
1604 }
1605
1606 /// <summary>
1607 /// Implements Explicit Reference conversions
1608 /// </summary>
1609 static Expression ExplicitReferenceConversion (Expression source, TypeSpec source_type, TypeSpec target_type)
1610 {
1611 //
1612 // From object to a generic parameter
1613 //
1614 if (source_type == TypeManager.object_type && TypeManager.IsGenericParameter (target_type))
1615 return source == null ? EmptyExpression.Null : new UnboxCast (source, target_type);
1616
1617 //
1618 // Explicit type parameter conversion.
1619 //
1620 if (TypeManager.IsGenericParameter (source_type))
1621 return ExplicitTypeParameterConversion (source, source_type, target_type);
1622
1623 bool target_is_value_type = TypeManager.IsStruct (target_type) || TypeManager.IsEnumType (target_type);
1624
1625 //
1626 // Unboxing conversion from System.ValueType to any non-nullable-value-type
1627 //
1628 if (source_type == TypeManager.value_type && target_is_value_type)
1629 return source == null ? EmptyExpression.Null : new UnboxCast (source, target_type);
1630
1631 //
1632 // From object to any reference type or value type (unboxing)
1633 //
1634 if (source_type == TypeManager.object_type)
1635 return
1636 source == null ? EmptyExpression.Null :
1637 target_is_value_type ? new UnboxCast (source, target_type) :
1638 source is Constant ? (Expression) new EmptyConstantCast ((Constant) source, target_type) :
1639 new ClassCast (source, target_type);
1640
1641 //
1642 // From any class S to any class-type T, provided S is a base class of T
1643 //
1644 if (TypeManager.IsSubclassOf (target_type, source_type))
1645 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1646
1647 //
1648 // From any interface-type S to to any class type T, provided T is not
1649 // sealed, or provided T implements S.
1650 //
1651 if (source_type.IsInterface) {
1652 if (!target_type.IsSealed || target_type.ImplementsInterface (source_type)) {
1653 if (target_type.IsClass)
1654 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1655
1656 //
1657 // Unboxing conversion from any interface-type to any non-nullable-value-type that
1658 // implements the interface-type
1659 //
1660 return source == null ? EmptyExpression.Null : new UnboxCast (source, target_type);
1661 }
1662
1663 //
1664 // From System.Collections.Generic.IList<T> and its base interfaces to a one-dimensional
1665 // array type S[], provided there is an implicit or explicit reference conversion from S to T.
1666 //
1667 var target_array = target_type as ArrayContainer;
1668 if (target_array != null && IList_To_Array (source_type, target_array))
1669 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1670
1671 return null;
1672 }
1673
1674 var source_array = source_type as ArrayContainer;
1675 if (source_array != null) {
1676 var target_array = target_type as ArrayContainer;
1677 if (target_array != null) {
1678 //
1679 // From System.Array to any array-type
1680 //
1681 if (source_type == TypeManager.array_type)
1682 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1683
1684 //
1685 // From an array type S with an element type Se to an array type T with an
1686 // element type Te provided all the following are true:
1687 // * S and T differe only in element type, in other words, S and T
1688 // have the same number of dimensions.
1689 // * Both Se and Te are reference types
1690 // * An explicit reference conversions exist from Se to Te
1691 //
1692 if (source_array.Rank == target_array.Rank) {
1693
1694 source_type = source_array.Element;
1695 if (!TypeManager.IsReferenceType (source_type))
1696 return null;
1697
1698 var target_element = target_array.Element;
1699 if (!TypeManager.IsReferenceType (target_element))
1700 return null;
1701
1702 if (ExplicitReferenceConversionExists (source_type, target_element))
1703 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1704
1705 return null;
1706 }
1707 }
1708
1709 //
1710 // From a single-dimensional array type S[] to System.Collections.Generic.IList<T> and its base interfaces,
1711 // provided that there is an explicit reference conversion from S to T
1712 //
1713 if (ArrayToIList (source_array, target_type, true))
1714 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1715
1716 return null;
1717 }
1718
1719 //
1720 // From any class type S to any interface T, provides S is not sealed
1721 // and provided S does not implement T.
1722 //
1723 if (target_type.IsInterface && !source_type.IsSealed && !source_type.ImplementsInterface (target_type)) {
1724 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1725 }
1726
1727 //
1728 // From System delegate to any delegate-type
1729 //
1730 if (source_type == TypeManager.delegate_type && TypeManager.IsDelegateType (target_type))
1731 return source == null ? EmptyExpression.Null : new ClassCast (source, target_type);
1732
1733 return null;
1734 }
1735
1736 /// <summary>
1737 /// Performs an explicit conversion of the expression `expr' whose
1738 /// type is expr.Type to `target_type'.
1739 /// </summary>
1740 static public Expression ExplicitConversionCore (ResolveContext ec, Expression expr,
1741 TypeSpec target_type, Location loc)
1742 {
1743 TypeSpec expr_type = expr.Type;
1744
1745 // Explicit conversion includes implicit conversion and it used for enum underlying types too
1746 Expression ne = ImplicitConversionStandard (ec, expr, target_type, loc, true);
1747 if (ne != null)
1748 return ne;
1749
1750 if (TypeManager.IsEnumType (expr_type)) {
1751 TypeSpec real_target = TypeManager.IsEnumType (target_type) ? EnumSpec.GetUnderlyingType (target_type) : target_type;
1752 Expression underlying = EmptyCast.Create (expr, EnumSpec.GetUnderlyingType (expr_type));
1753 if (underlying.Type == real_target)
1754 ne = underlying;
1755
1756 if (ne == null)
1757 ne = ImplicitNumericConversion (underlying, real_target);
1758
1759 if (ne == null)
1760 ne = ExplicitNumericConversion (underlying, real_target);
1761
1762 //
1763 // LAMESPEC: IntPtr and UIntPtr conversion to any Enum is allowed
1764 //
1765 if (ne == null && (real_target == TypeManager.intptr_type || real_target == TypeManager.uintptr_type))
1766 ne = ExplicitUserConversion (ec, underlying, real_target, loc);
1767
1768 return ne != null ? EmptyCast.Create (ne, target_type) : null;
1769 }
1770
1771 if (TypeManager.IsEnumType (target_type)) {
1772 //
1773 // System.Enum can be unboxed to any enum-type
1774 //
1775 if (expr_type == TypeManager.enum_type)
1776 return new UnboxCast (expr, target_type);
1777
1778 TypeSpec real_target = TypeManager.IsEnumType (target_type) ? EnumSpec.GetUnderlyingType (target_type) : target_type;
1779
1780 if (expr_type == real_target)
1781 return EmptyCast.Create (expr, target_type);
1782
1783 ne = ImplicitNumericConversion (expr, real_target);
1784 if (ne != null)
1785 return EmptyCast.Create (ne, target_type);
1786
1787 ne = ExplicitNumericConversion (expr, real_target);
1788 if (ne != null)
1789 return EmptyCast.Create (ne, target_type);
1790
1791 //
1792 // LAMESPEC: IntPtr and UIntPtr conversion to any Enum is allowed
1793 //
1794 if (expr_type == TypeManager.intptr_type || expr_type == TypeManager.uintptr_type) {
1795 ne = ExplicitUserConversion (ec, expr, real_target, loc);
1796 if (ne != null)
1797 return ExplicitConversionCore (ec, ne, target_type, loc);
1798 }
1799 } else {
1800 ne = ExplicitNumericConversion (expr, target_type);
1801 if (ne != null)
1802 return ne;
1803 }
1804
1805 //
1806 // Skip the ExplicitReferenceConversion because we can not convert
1807 // from Null to a ValueType, and ExplicitReference wont check against
1808 // null literal explicitly
1809 //
1810 if (expr_type != TypeManager.null_type){
1811 ne = ExplicitReferenceConversion (expr, expr_type, target_type);
1812 if (ne != null)
1813 return ne;
1814 }
1815
1816 if (ec.IsUnsafe){
1817 ne = ExplicitUnsafe (expr, target_type);
1818 if (ne != null)
1819 return ne;
1820 }
1821
1822 return null;
1823 }
1824
1825 public static Expression ExplicitUnsafe (Expression expr, TypeSpec target_type)
1826 {
1827 TypeSpec expr_type = expr.Type;
1828
1829 if (target_type.IsPointer){
1830 if (expr_type.IsPointer)
1831 return EmptyCast.Create (expr, target_type);
1832
1833 if (expr_type == TypeManager.sbyte_type ||
1834 expr_type == TypeManager.short_type ||
1835 expr_type == TypeManager.int32_type)
1836 return new OpcodeCast (expr, target_type, OpCodes.Conv_I);
1837
1838 if (expr_type == TypeManager.ushort_type ||
1839 expr_type == TypeManager.uint32_type ||
1840 expr_type == TypeManager.byte_type)
1841 return new OpcodeCast (expr, target_type, OpCodes.Conv_U);
1842
1843 if (expr_type == TypeManager.int64_type)
1844 return new ConvCast (expr, target_type, ConvCast.Mode.I8_I);
1845
1846 if (expr_type == TypeManager.uint64_type)
1847 return new ConvCast (expr, target_type, ConvCast.Mode.U8_I);
1848 }
1849
1850 if (expr_type.IsPointer){
1851 if (target_type == TypeManager.sbyte_type)
1852 return new OpcodeCast (expr, target_type, OpCodes.Conv_I1);
1853 if (target_type == TypeManager.byte_type)
1854 return new OpcodeCast (expr, target_type, OpCodes.Conv_U1);
1855 if (target_type == TypeManager.short_type)
1856 return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
1857 if (target_type == TypeManager.ushort_type)
1858 return new OpcodeCast (expr, target_type, OpCodes.Conv_U2);
1859 if (target_type == TypeManager.int32_type)
1860 return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
1861 if (target_type == TypeManager.uint32_type)
1862 return new OpcodeCast (expr, target_type, OpCodes.Conv_U4);
1863 if (target_type == TypeManager.int64_type)
1864 return new ConvCast (expr, target_type, ConvCast.Mode.I_I8);
1865 if (target_type == TypeManager.uint64_type)
1866 return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
1867 }
1868 return null;
1869 }
1870
1871 /// <summary>
1872 /// Same as ExplicitConversion, only it doesn't include user defined conversions
1873 /// </summary>
1874 static public Expression ExplicitConversionStandard (ResolveContext ec, Expression expr,
1875 TypeSpec target_type, Location l)
1876 {
1877 int errors = ec.Report.Errors;
1878 Expression ne = ImplicitConversionStandard (ec, expr, target_type, l);
1879 if (ec.Report.Errors > errors)
1880 return null;
1881
1882 if (ne != null)
1883 return ne;
1884
1885 ne = ExplicitNumericConversion (expr, target_type);
1886 if (ne != null)
1887 return ne;
1888
1889 ne = ExplicitReferenceConversion (expr, expr.Type, target_type);
1890 if (ne != null)
1891 return ne;
1892
1893 if (ec.IsUnsafe && expr.Type == TypeManager.void_ptr_type && target_type.IsPointer)
1894 return EmptyCast.Create (expr, target_type);
1895
1896 expr.Error_ValueCannotBeConverted (ec, l, target_type, true);
1897 return null;
1898 }
1899
1900 /// <summary>
1901 /// Performs an explicit conversion of the expression `expr' whose
1902 /// type is expr.Type to `target_type'.
1903 /// </summary>
1904 static public Expression ExplicitConversion (ResolveContext ec, Expression expr,
1905 TypeSpec target_type, Location loc)
1906 {
1907 Expression e = ExplicitConversionCore (ec, expr, target_type, loc);
1908 if (e != null) {
1909 //
1910 // Don't eliminate explicit precission casts
1911 //
1912 if (e == expr) {
1913 if (target_type == TypeManager.float_type)
1914 return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
1915
1916 if (target_type == TypeManager.double_type)
1917 return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
1918 }
1919
1920 return e;
1921 }
1922
1923 TypeSpec expr_type = expr.Type;
1924 if (TypeManager.IsNullableType (target_type)) {
1925 if (TypeManager.IsNullableType (expr_type)) {
1926 TypeSpec target = Nullable.NullableInfo.GetUnderlyingType (target_type);
1927 Expression unwrap = Nullable.Unwrap.Create (expr);
1928 e = ExplicitConversion (ec, unwrap, target, expr.Location);
1929 if (e == null)
1930 return null;
1931
1932 return new Nullable.Lifted (e, unwrap, target_type).Resolve (ec);
1933 } else if (expr_type == TypeManager.object_type) {
1934 return new UnboxCast (expr, target_type);
1935 } else {
1936 TypeSpec target = TypeManager.GetTypeArguments (target_type) [0];
1937
1938 e = ExplicitConversionCore (ec, expr, target, loc);
1939 if (e != null)
1940 return Nullable.Wrap.Create (e, target_type);
1941 }
1942 } else if (TypeManager.IsNullableType (expr_type)) {
1943 e = ImplicitBoxingConversion (expr, Nullable.NullableInfo.GetUnderlyingType (expr_type), target_type);
1944 if (e != null)
1945 return e;
1946
1947 e = Nullable.Unwrap.Create (expr, false);
1948 e = ExplicitConversionCore (ec, e, target_type, loc);
1949 if (e != null)
1950 return EmptyCast.Create (e, target_type);
1951 }
1952
1953 e = ExplicitUserConversion (ec, expr, target_type, loc);
1954 if (e != null)
1955 return e;
1956
1957 expr.Error_ValueCannotBeConverted (ec, loc, target_type, true);
1958 return null;
1959 }
1960 }
1961 }
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