/*
* BindImplicitConversion
*
* This is a complex routine with complex parameters. Generally, this should
* be called through one of the helper methods that insulates you
* from the complexity of the interface. This routine handles all the logic
* associated with implicit conversions.
*
* exprSrc - the expression being converted. Can be null if only type conversion
* info is being supplied.
* typeSrc - type of the source
* typeDest - type of the destination
* exprDest - returns an expression of the src converted to the dest. If null, we
* only care about whether the conversion can be attempted, not the
* expression tree.
* flags - flags possibly customizing the conversions allowed. E.g., can suppress
* user-defined conversions.
*
* returns true if the conversion can be made, false if not.
*/
public bool Bind()
{
// 13.1 Implicit conversions
//
// The following conversions are classified as implicit conversions:
//
// * Identity conversions
// * Implicit numeric conversions
// * Implicit enumeration conversions
// * Implicit reference conversions
// * Boxing conversions
// * Implicit type parameter conversions
// * Implicit constant expression conversions
// * User-defined implicit conversions
// * Implicit conversions from an anonymous method expression to a compatible delegate type
// * Implicit conversion from a method group to a compatible delegate type
// * Conversions from the null type (11.2.7) to any nullable type
// * Implicit nullable conversions
// * Lifted user-defined implicit conversions
//
// Implicit conversions can occur in a variety of situations, including function member invocations
// (14.4.3), cast expressions (14.6.6), and assignments (14.14).
// Can't convert to or from the error type.
if (typeSrc == null || typeDest == null || typeDest.IsNeverSameType())
{
return(false);
}
Debug.Assert(typeSrc != null && typeDest != null); // types must be supplied.
Debug.Assert(exprSrc == null || typeSrc == exprSrc.type); // type of source should be correct if source supplied
Debug.Assert(!needsExprDest || exprSrc != null); // need source expr to create dest expr
switch (typeDest.GetTypeKind())
{
case TypeKind.TK_ErrorType:
Debug.Assert(typeDest.AsErrorType().HasTypeParent() || typeDest.AsErrorType().HasNSParent());
if (typeSrc != typeDest)
{
return(false);
}
if (needsExprDest)
{
exprDest = exprSrc;
}
return(true);
case TypeKind.TK_NullType:
// Can only convert to the null type if src is null.
if (!typeSrc.IsNullType())
{
return(false);
}
if (needsExprDest)
{
exprDest = exprSrc;
}
return(true);
case TypeKind.TK_MethodGroupType:
VSFAIL("Something is wrong with Type.IsNeverSameType()");
return(false);
case TypeKind.TK_NaturalIntegerType:
case TypeKind.TK_ArgumentListType:
return(typeSrc == typeDest);
case TypeKind.TK_VoidType:
return(false);
default:
break;
}
if (typeSrc.IsErrorType())
{
Debug.Assert(!typeDest.IsErrorType());
return(false);
}
// 13.1.1 Identity conversion
//
// An identity conversion converts from any type to the same type. This conversion exists only
// such that an entity that already has a required type can be said to be convertible to that type.
if (typeSrc == typeDest &&
((flags & CONVERTTYPE.ISEXPLICIT) == 0 || (!typeSrc.isPredefType(PredefinedType.PT_FLOAT) && !typeSrc.isPredefType(PredefinedType.PT_DOUBLE))))
{
if (needsExprDest)
{
exprDest = exprSrc;
}
return(true);
}
if (typeDest.IsNullableType())
{
return(BindNubConversion(typeDest.AsNullableType()));
}
if (typeSrc.IsNullableType())
{
return(bindImplicitConversionFromNullable(typeSrc.AsNullableType()));
}
if ((flags & CONVERTTYPE.ISEXPLICIT) != 0)
{
flags |= CONVERTTYPE.NOUDC;
}
// Get the fundamental types of destination.
FUNDTYPE ftDest = typeDest.fundType();
Debug.Assert(ftDest != FUNDTYPE.FT_NONE || typeDest.IsParameterModifierType());
switch (typeSrc.GetTypeKind())
{
default:
VSFAIL("Bad type symbol kind");
break;
case TypeKind.TK_MethodGroupType:
if (exprSrc.isMEMGRP())
{
EXPRCALL outExpr;
bool retVal = binder.BindGrpConversion(exprSrc.asMEMGRP(), typeDest, needsExprDest, out outExpr, false);
exprDest = outExpr;
return(retVal);
}
return(false);
case TypeKind.TK_VoidType:
case TypeKind.TK_ErrorType:
case TypeKind.TK_ParameterModifierType:
case TypeKind.TK_ArgumentListType:
return(false);
case TypeKind.TK_NullType:
if (bindImplicitConversionFromNull())
{
return(true);
}
// If not, try user defined implicit conversions.
break;
case TypeKind.TK_ArrayType:
if (bindImplicitConversionFromArray())
{
return(true);
}
// If not, try user defined implicit conversions.
break;
case TypeKind.TK_PointerType:
if (bindImplicitConversionFromPointer())
{
return(true);
}
// If not, try user defined implicit conversions.
break;
case TypeKind.TK_TypeParameterType:
if (bindImplicitConversionFromTypeVar(typeSrc.AsTypeParameterType()))
{
return(true);
}
// If not, try user defined implicit conversions.
break;
case TypeKind.TK_AggregateType:
// TypeReference and ArgIterator can't be boxed (or converted to anything else)
if (typeSrc.isSpecialByRefType())
{
return(false);
}
if (bindImplicitConversionFromAgg(typeSrc.AsAggregateType()))
{
return(true);
}
// If not, try user defined implicit conversions.
break;
}
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// RUNTIME BINDER ONLY CHANGE
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
//
// Every incoming dynamic operand should be implicitly convertible
// to any type that it is an instance of.
if (exprSrc != null &&
exprSrc.RuntimeObject != null &&
typeDest.AssociatedSystemType.IsInstanceOfType(exprSrc.RuntimeObject) &&
binder.GetSemanticChecker().CheckTypeAccess(typeDest, binder.Context.ContextForMemberLookup()))
{
if (needsExprDest)
{
binder.bindSimpleCast(exprSrc, exprTypeDest, out exprDest, exprSrc.flags & EXPRFLAG.EXF_CANTBENULL);
}
return(true);
}
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// END RUNTIME BINDER ONLY CHANGE
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// 13.1.8 User-defined implicit conversions
//
// A user-defined implicit conversion consists of an optional standard implicit conversion,
// followed by execution of a user-defined implicit conversion operator, followed by another
// optional standard implicit conversion. The exact rules for evaluating user-defined
// conversions are described in 13.4.3.
if (0 == (flags & CONVERTTYPE.NOUDC))
{
return(binder.bindUserDefinedConversion(exprSrc, typeSrc, typeDest, needsExprDest, out exprDest, true));
}
// No conversion was found.
return(false);
}
////////////////////////////////////////////////////////////////////////////////
private bool MethodGroupReturnTypeInference(EXPR pSource, CType pType)
{
// SPEC: Otherwise, if E is a method group and T is a delegate CType or
// SPEC: expression tree CType with parameter types T1...Tk and return
// SPEC: CType Tb and overload resolution of E with the types T1...Tk
// SPEC: yields a single method with return CType U then a lower-bound
// SPEC: inference is made from U to Tb.
if (!pSource.isMEMGRP())
{
return false;
}
pType = pType.GetDelegateTypeOfPossibleExpression();
if (!pType.isDelegateType())
{
return false;
}
AggregateType pDelegateType = pType.AsAggregateType();
CType pDelegateReturnType = pDelegateType.GetDelegateReturnType(GetSymbolLoader());
if (pDelegateReturnType == null)
{
return false;
}
if (pDelegateReturnType.IsVoidType())
{
return false;
}
// At this point we are in the second phase; we know that all the input types are fixed.
TypeArray pDelegateParameters = GetFixedDelegateParameters(pDelegateType);
if (pDelegateParameters == null)
{
return false;
}
ArgInfos argInfo = new ArgInfos() { carg = pDelegateParameters.size, types = pDelegateParameters, fHasExprs = false, prgexpr = null };
var argsBinder = new ExpressionBinder.GroupToArgsBinder(_binder, 0/* flags */, pSource.asMEMGRP(), argInfo, null, false, pDelegateType);
bool success = argsBinder.Bind(false);
if (!success)
{
return false;
}
MethPropWithInst mwi = argsBinder.GetResultsOfBind().GetBestResult();
CType pMethodReturnType = GetTypeManager().SubstType(mwi.Meth().RetType,
mwi.GetType(), mwi.TypeArgs);
if (pMethodReturnType.IsVoidType())
{
return false;
}
LowerBoundInference(pMethodReturnType, pDelegateReturnType);
return true;
}
////////////////////////////////////////////////////////////////////////////////
// A false return means not to process the expr any further - it's totally out
// of place. For example - a method group or an anonymous method.
internal bool checkLvalue(EXPR expr, CheckLvalueKind kind)
{
if (!expr.isOK())
return false;
if (expr.isLvalue())
{
if (expr.isPROP())
{
CheckLvalueProp(expr.asPROP());
}
markFieldAssigned(expr);
return true;
}
switch (expr.kind)
{
case ExpressionKind.EK_PROP:
if (kind == CheckLvalueKind.OutParameter)
{
// passing a property as ref or out
ErrorContext.Error(ErrorCode.ERR_RefProperty);
return true;
}
if (!expr.asPROP().mwtSet)
{
// Assigning to a property without a setter.
// If we have
// bool? b = true; (bool)b = false;
// then this is realized immediately as
// b.Value = false;
// and no ExpressionKind.EK_CAST is generated. We'd rather not give a "you're writing
// to a read-only property" error in the case where the property access
// is not explicit in the source code. Fortunately in this case the
// cast is still hanging around in the parse tree, so we can look for it.
// POSSIBLE ERROR: It would be nice to also give this error for other situations
// POSSIBLE ERROR: in which the user is attempting to assign to a value, such as
// POSSIBLE ERROR: an explicit (bool)b.Value = false;
// POSSIBLE ERROR: Unfortunately we cannot use this trick in that situation because
// POSSIBLE ERROR: we've already discarded the OperatorKind.OP_CAST node. (This is an SyntaxKind.Dot).
// SPEC VIOLATION: More generally:
// SPEC VIOLATION: The spec states that the result of any cast is a value, not a
// SPEC VIOLATION: variable. Unfortunately we do not correctly implement this
// SPEC VIOLATION: and we probably should not start implementing it because this
// SPEC VIOLATION: would be a breaking change. We currently discard "no op" casts
// SPEC VIOLATION: very aggressively rather than generating an ExpressionKind.EK_CAST node.
ErrorContext.Error(ErrorCode.ERR_AssgReadonlyProp, expr.asPROP().pwtSlot);
return true;
}
break;
case ExpressionKind.EK_ARRAYLENGTH:
if (kind == CheckLvalueKind.OutParameter)
{
// passing a property as ref or out
ErrorContext.Error(ErrorCode.ERR_RefProperty);
}
else
{
// Special case, the length property of an array
ErrorContext.Error(ErrorCode.ERR_AssgReadonlyProp, GetSymbolLoader().getPredefinedMembers().GetProperty(PREDEFPROP.PP_ARRAY_LENGTH));
}
return true;
case ExpressionKind.EK_BOUNDLAMBDA:
case ExpressionKind.EK_UNBOUNDLAMBDA:
case ExpressionKind.EK_CONSTANT:
ErrorContext.Error(GetStandardLvalueError(kind));
return false;
case ExpressionKind.EK_MEMGRP:
{
ErrorCode err = (kind == CheckLvalueKind.OutParameter) ? ErrorCode.ERR_RefReadonlyLocalCause : ErrorCode.ERR_AssgReadonlyLocalCause;
ErrorContext.Error(err, expr.asMEMGRP().name, new ErrArgIds(MessageID.MethodGroup));
return false;
}
default:
break;
}
return !TryReportLvalueFailure(expr, kind);
}
