/// <remarks>
/// From ExpressionBinder::EnsureQMarkTypesCompatible:
///
/// The v2.0 specification states that the types of the second and third operands T and S of a ternary operator
/// must be TT and TS such that either (a) TT==TS, or (b), TT->TS or TS->TT but not both.
///
/// Unfortunately that is not what we implemented in v2.0. Instead, we implemented
/// that either (a) TT=TS or (b) T->TS or S->TT but not both. That is, we looked at the
/// convertibility of the expressions, not the types.
///
///
/// Changing that to the algorithm in the standard would be a breaking change.
///
/// b ? (Func<int>)(delegate(){return 1;}) : (delegate(){return 2;})
///
/// and
///
/// b ? 0 : myenum
///
/// would suddenly stop working. (The first because o2 has no type, the second because 0 goes to
/// any enum but enum doesn't go to int.)
///
/// It gets worse. We would like the 3.0 language features which require type inference to use
/// a consistent algorithm, and that furthermore, the algorithm be smart about choosing the best
/// of a set of types. However, the language committee has decided that this algorithm will NOT
/// consume information about the convertibility of expressions. Rather, it will gather up all
/// the possible types and then pick the "largest" of them.
///
/// To maintain backwards compatibility while still participating in the spirit of consistency,
/// we implement an algorithm here which picks the type based on expression convertibility, but
/// if there is a conflict, then it chooses the larger type rather than producing a type error.
/// This means that b?0:myshort will have type int rather than producing an error (because 0->short,
/// myshort->int).
/// </remarks>
private BoundExpression BindConditionalOperator(ConditionalExpressionSyntax node, DiagnosticBag diagnostics)
{
BoundExpression condition = BindBooleanExpression(node.Condition, diagnostics);
BoundExpression trueExpr = BindValue(node.WhenTrue, diagnostics, BindValueKind.RValue);
BoundExpression falseExpr = BindValue(node.WhenFalse, diagnostics, BindValueKind.RValue);
TypeSymbol trueType = trueExpr.Type;
TypeSymbol falseType = falseExpr.Type;
TypeSymbol type;
bool hasErrors = false;
if (trueType == falseType)
{
// NOTE: Dev10 lets the type inferrer handle this case (presumably, for maximum consistency),
// but it seems like a worthwhile short-circuit for a common case.
if ((object)trueType == null)
{
// If trueExpr and falseExpr both have type null, then we don't have any symbols
// to pass to a SymbolDistinguisher (which ERR_InvalidQM would usually require).
diagnostics.Add(ErrorCode.ERR_InvalidQM, node.Location, trueExpr.Display, falseExpr.Display);
type = CreateErrorType();
hasErrors = true;
}
else
{
// <expr> ? T : T
type = trueType;
}
}
else
{
bool hadMultipleCandidates;
HashSet<DiagnosticInfo> useSiteDiagnostics = null;
TypeSymbol bestType = BestTypeInferrer.InferBestTypeForConditionalOperator(trueExpr, falseExpr, this.Conversions, out hadMultipleCandidates, ref useSiteDiagnostics);
diagnostics.Add(node, useSiteDiagnostics);
if ((object)bestType == null)
{
// CONSIDER: Dev10 suppresses ERR_InvalidQM unless the following is true for both trueType and falseType
// (!T->type->IsErrorType() || T->type->AsErrorType()->HasTypeParent() || T->type->AsErrorType()->HasNSParent())
if (hadMultipleCandidates)
{
diagnostics.Add(ErrorCode.ERR_AmbigQM, node.Location, trueExpr.Display, falseExpr.Display);
}
else
{
object trueArg = trueExpr.Display;
object falseArg = falseExpr.Display;
Symbol trueSymbol = trueArg as Symbol;
Symbol falseSymbol = falseArg as Symbol;
if ((object)trueSymbol != null && (object)falseSymbol != null)
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(this.Compilation, trueSymbol, falseSymbol);
trueArg = distinguisher.First;
falseArg = distinguisher.Second;
}
diagnostics.Add(ErrorCode.ERR_InvalidQM, node.Location, trueArg, falseArg);
}
type = CreateErrorType();
hasErrors = true;
}
else if (bestType.IsErrorType())
{
type = bestType;
hasErrors = true;
}
else
{
trueExpr = GenerateConversionForAssignment(bestType, trueExpr, diagnostics);
falseExpr = GenerateConversionForAssignment(bestType, falseExpr, diagnostics);
if (trueExpr.HasAnyErrors || falseExpr.HasAnyErrors)
{
// If one of the conversions went wrong (e.g. return type of method group being converted
// didn't match), then we don't want to use bestType because it's not accurate.
type = CreateErrorType();
hasErrors = true;
}
else
{
type = bestType;
}
}
}
ConstantValue constantValue = null;
if (!hasErrors)
{
constantValue = FoldConditionalOperator(condition, trueExpr, falseExpr);
hasErrors = constantValue != null && constantValue.IsBad;
}
return new BoundConditionalOperator(node, condition, trueExpr, falseExpr, constantValue, type, hasErrors);
}
private BoundForEachStatement BindForEachPartsWorker(DiagnosticBag diagnostics)
{
BoundExpression collectionExpr = this.Next.BindValue(syntax.Expression, diagnostics, BindValueKind.RValue); //bind with next to avoid seeing iteration variable
ForEachEnumeratorInfo.Builder builder = new ForEachEnumeratorInfo.Builder();
TypeSymbol inferredType;
bool hasErrors = !GetEnumeratorInfoAndInferCollectionElementType(ref builder, ref collectionExpr, diagnostics, out inferredType);
// These should only occur when special types are missing or malformed.
hasErrors = hasErrors ||
(object)builder.GetEnumeratorMethod == null ||
(object)builder.MoveNextMethod == null ||
(object)builder.CurrentPropertyGetter == null;
// Check for local variable conflicts in the *enclosing* binder; obviously the *current*
// binder has a local that matches!
hasErrors |= this.ValidateDeclarationNameConflictsInScope(IterationVariable, diagnostics);
// If the type in syntax is "var", then the type should be set explicitly so that the
// Type property doesn't fail.
TypeSyntax typeSyntax = this.syntax.Type;
bool isVar;
AliasSymbol alias;
TypeSymbol declType = BindType(typeSyntax, diagnostics, out isVar, out alias);
TypeSymbol iterationVariableType;
if (isVar)
{
iterationVariableType = inferredType ?? CreateErrorType("var");
}
else
{
Debug.Assert((object)declType != null);
iterationVariableType = declType;
}
BoundTypeExpression boundIterationVariableType = new BoundTypeExpression(typeSyntax, alias, iterationVariableType);
this.IterationVariable.SetTypeSymbol(iterationVariableType);
BoundStatement body = BindPossibleEmbeddedStatement(syntax.Statement, diagnostics);
hasErrors = hasErrors || iterationVariableType.IsErrorType();
// Skip the conversion checks and array/enumerator differentiation if we know we have an error.
if (hasErrors)
{
return(new BoundForEachStatement(
syntax,
ImmutableArray <LocalSymbol> .Empty,
null, // can't be sure that it's complete
default(Conversion),
boundIterationVariableType,
this.IterationVariable,
collectionExpr,
body,
CheckOverflowAtRuntime,
this.BreakLabel,
this.ContinueLabel,
hasErrors));
}
var foreachKeyword = syntax.ForEachKeyword;
ReportDiagnosticsIfObsolete(diagnostics, builder.GetEnumeratorMethod, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.MoveNextMethod, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.CurrentPropertyGetter, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.CurrentPropertyGetter.AssociatedSymbol, foreachKeyword, hasBaseReceiver: false);
// We want to convert from inferredType in the array/string case and builder.ElementType in the enumerator case,
// but it turns out that these are equivalent (when both are available).
HashSet <DiagnosticInfo> useSiteDiagnostics = null;
Conversion elementConversion = this.Conversions.ClassifyConversionForCast(inferredType, iterationVariableType, ref useSiteDiagnostics);
if (!elementConversion.IsValid)
{
ImmutableArray <MethodSymbol> originalUserDefinedConversions = elementConversion.OriginalUserDefinedConversions;
if (originalUserDefinedConversions.Length > 1)
{
diagnostics.Add(ErrorCode.ERR_AmbigUDConv, syntax.ForEachKeyword.GetLocation(), originalUserDefinedConversions[0], originalUserDefinedConversions[1], inferredType, iterationVariableType);
}
else
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(this.Compilation, inferredType, iterationVariableType);
diagnostics.Add(ErrorCode.ERR_NoExplicitConv, syntax.ForEachKeyword.GetLocation(), distinguisher.First, distinguisher.Second);
}
hasErrors = true;
}
else
{
ReportDiagnosticsIfObsolete(diagnostics, elementConversion, syntax.ForEachKeyword, hasBaseReceiver: false);
}
// Spec (§8.8.4):
// If the type X of expression is dynamic then there is an implicit conversion from >>expression<< (not the type of the expression)
// to the System.Collections.IEnumerable interface (§6.1.8).
builder.CollectionConversion = this.Conversions.ClassifyConversionFromExpression(collectionExpr, builder.CollectionType, ref useSiteDiagnostics);
builder.CurrentConversion = this.Conversions.ClassifyConversion(builder.CurrentPropertyGetter.ReturnType, builder.ElementType, ref useSiteDiagnostics);
builder.EnumeratorConversion = this.Conversions.ClassifyConversion(builder.GetEnumeratorMethod.ReturnType, GetSpecialType(SpecialType.System_Object, diagnostics, this.syntax), ref useSiteDiagnostics);
diagnostics.Add(syntax.ForEachKeyword.GetLocation(), useSiteDiagnostics);
// Due to the way we extracted the various types, these conversions should always be possible.
// CAVEAT: if we're iterating over an array of pointers, the current conversion will fail since we
// can't convert from object to a pointer type. Similarly, if we're iterating over an array of
// Nullable<Error>, the current conversion will fail because we don't know if an ErrorType is a
// value type. This doesn't matter in practice, since we won't actually use the enumerator pattern
// when we lower the loop.
Debug.Assert(builder.CollectionConversion.IsValid);
Debug.Assert(builder.CurrentConversion.IsValid ||
(builder.ElementType.IsPointerType() && collectionExpr.Type.IsArray()) ||
(builder.ElementType.IsNullableType() && builder.ElementType.GetMemberTypeArgumentsNoUseSiteDiagnostics().Single().IsErrorType() && collectionExpr.Type.IsArray()));
Debug.Assert(builder.EnumeratorConversion.IsValid ||
this.Compilation.GetSpecialType(SpecialType.System_Object).TypeKind == TypeKind.Error,
"Conversions to object succeed unless there's a problem with the object type");
// If user-defined conversions could occur here, we would need to check for ObsoleteAttribute.
Debug.Assert((object)builder.CollectionConversion.Method == null,
"Conversion from collection expression to collection type should not be user-defined");
Debug.Assert((object)builder.CurrentConversion.Method == null,
"Conversion from Current property type to element type should not be user-defined");
Debug.Assert((object)builder.EnumeratorConversion.Method == null,
"Conversion from GetEnumerator return type to System.Object should not be user-defined");
// We're wrapping the collection expression in a (non-synthesized) conversion so that its converted
// type (i.e. builder.CollectionType) will be available in the binding API.
BoundConversion convertedCollectionExpression = new BoundConversion(
collectionExpr.Syntax,
collectionExpr,
builder.CollectionConversion,
CheckOverflowAtRuntime,
false,
ConstantValue.NotAvailable,
builder.CollectionType);
return(new BoundForEachStatement(
syntax,
ImmutableArray <LocalSymbol> .Empty,
builder.Build(this.Flags),
elementConversion,
boundIterationVariableType,
this.IterationVariable,
convertedCollectionExpression,
body,
CheckOverflowAtRuntime,
this.BreakLabel,
this.ContinueLabel,
hasErrors));
}
private static bool ReportAsOperatorConversionDiagnostics(
CSharpSyntaxNode node,
DiagnosticBag diagnostics,
Compilation compilation,
TypeSymbol operandType,
TypeSymbol targetType,
ConversionKind conversionKind,
ConstantValue operandConstantValue)
{
// SPEC: In an operation of the form E as T, E must be an expression and T must be a reference type,
// SPEC: a type parameter known to be a reference type, or a nullable type.
// SPEC: Furthermore, at least one of the following must be true, or otherwise a compile-time error occurs:
// SPEC: • An identity (§6.1.1), implicit nullable (§6.1.4), implicit reference (§6.1.6), boxing (§6.1.7),
// SPEC: explicit nullable (§6.2.3), explicit reference (§6.2.4), or unboxing (§6.2.5) conversion exists
// SPEC: from E to T.
// SPEC: • The type of E or T is an open type.
// SPEC: • E is the null literal.
// SPEC VIOLATION: The specification contains an error in the list of legal conversions above.
// SPEC VIOLATION: If we have "class C<T, U> where T : U where U : class" then there is
// SPEC VIOLATION: an implicit conversion from T to U, but it is not an identity, reference or
// SPEC VIOLATION: boxing conversion. It will be one of those at runtime, but at compile time
// SPEC VIOLATION: we do not know which, and therefore cannot classify it as any of those.
// SPEC VIOLATION: See Microsoft.CodeAnalysis.CSharp.UnitTests.SyntaxBinderTests.TestAsOperator_SpecErrorCase() test for an example.
// SPEC VIOLATION: The specification also unintentionally allows the case where requirement 2 above:
// SPEC VIOLATION: "The type of E or T is an open type" is true, but type of E is void type, i.e. T is an open type.
// SPEC VIOLATION: Dev10 compiler correctly generates an error for this case and we will maintain compatibility.
bool hasErrors = false;
switch (conversionKind)
{
case ConversionKind.ImplicitReference:
case ConversionKind.Boxing:
case ConversionKind.ImplicitNullable:
case ConversionKind.Identity:
case ConversionKind.ExplicitNullable:
case ConversionKind.ExplicitReference:
case ConversionKind.Unboxing:
break;
default:
// Generate an error if there is no possible legal conversion and both the operandType
// and the targetType are closed types OR operandType is void type, otherwise we need a runtime check
if (!operandType.ContainsTypeParameter() && !targetType.ContainsTypeParameter() ||
operandType.SpecialType == SpecialType.System_Void)
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(compilation, operandType, targetType);
Error(diagnostics, ErrorCode.ERR_NoExplicitBuiltinConv, node, distinguisher.First, distinguisher.Second);
hasErrors = true;
}
break;
}
if (!hasErrors)
{
ReportAsOperatorConstantWarnings(node, diagnostics, operandType, targetType, conversionKind, operandConstantValue);
}
return hasErrors;
}
internal void GenerateAnonymousFunctionConversionError(DiagnosticBag diagnostics, CSharpSyntaxNode syntax,
UnboundLambda anonymousFunction, TypeSymbol targetType)
{
Debug.Assert((object)targetType != null);
Debug.Assert(anonymousFunction != null);
// Is the target type simply bad?
// If the target type is an error then we've already reported a diagnostic. Don't bother
// reporting the conversion error.
if (targetType.IsErrorType() || syntax.HasErrors)
{
return;
}
// CONSIDER: Instead of computing this again, cache the reason why the conversion failed in
// CONSIDER: the Conversion result, and simply report that.
var reason = Conversions.IsAnonymousFunctionCompatibleWithType(anonymousFunction, targetType);
// It is possible that the conversion from lambda to delegate is just fine, and
// that we ended up here because the target type, though itself is not an error
// type, contains a type argument which is an error type. For example, converting
// (Foo foo)=>{} to Action<Foo> is a perfectly legal conversion even if Foo is undefined!
// In that case we have already reported an error that Foo is undefined, so just bail out.
if (reason == LambdaConversionResult.Success)
{
return;
}
var id = anonymousFunction.MessageID.Localize();
if (reason == LambdaConversionResult.BadTargetType)
{
if (ReportDelegateInvokeUseSiteDiagnostic(diagnostics, targetType, node: syntax))
{
return;
}
// Cannot convert {0} to type '{1}' because it is not a delegate type
Error(diagnostics, ErrorCode.ERR_AnonMethToNonDel, syntax, id, targetType);
return;
}
if (reason == LambdaConversionResult.ExpressionTreeMustHaveDelegateTypeArgument)
{
Debug.Assert(targetType.IsExpressionTree());
Error(diagnostics, ErrorCode.ERR_ExpressionTreeMustHaveDelegate, syntax, ((NamedTypeSymbol)targetType).TypeArgumentsNoUseSiteDiagnostics[0]);
return;
}
if (reason == LambdaConversionResult.ExpressionTreeFromAnonymousMethod)
{
Debug.Assert(targetType.IsExpressionTree());
Error(diagnostics, ErrorCode.ERR_AnonymousMethodToExpressionTree, syntax);
return;
}
// At this point we know that we have either a delegate type or an expression type for the target.
var delegateType = targetType.GetDelegateType();
// The target type is a vaid delegate or expression tree type. Is there something wrong with the
// parameter list?
// First off, is there a parameter list at all?
if (reason == LambdaConversionResult.MissingSignatureWithOutParameter)
{
// COMPATIBILITY: The C# 4 compiler produces two errors for:
//
// delegate void D (out int x);
// ...
// D d = delegate {};
//
// error CS1676: Parameter 1 must be declared with the 'out' keyword
// error CS1688: Cannot convert anonymous method block without a parameter list
// to delegate type 'D' because it has one or more out parameters
//
// This seems redundant, (because there is no "parameter 1" in the source code)
// and unnecessary. I propose that we eliminate the first error.
Error(diagnostics, ErrorCode.ERR_CantConvAnonMethNoParams, syntax, targetType);
return;
}
// There is a parameter list. Does it have the right number of elements?
if (reason == LambdaConversionResult.BadParameterCount)
{
// Delegate '{0}' does not take {1} arguments
Error(diagnostics, ErrorCode.ERR_BadDelArgCount, syntax, targetType, anonymousFunction.ParameterCount);
return;
}
// The parameter list exists and had the right number of parameters. Were any of its types bad?
// If any parameter type of the lambda is an error type then suppress
// further errors. We've already reported errors on the bad type.
if (anonymousFunction.HasExplicitlyTypedParameterList)
{
for (int i = 0; i < anonymousFunction.ParameterCount; ++i)
{
if (anonymousFunction.ParameterType(i).IsErrorType())
{
return;
}
}
}
// The parameter list exists and had the right number of parameters. Were any of its types
// mismatched with the delegate parameter types?
// The simplest possible case is (x, y, z)=>whatever where the target type has a ref or out parameter.
var delegateParameters = delegateType.DelegateParameters();
if (reason == LambdaConversionResult.RefInImplicitlyTypedLambda)
{
for (int i = 0; i < anonymousFunction.ParameterCount; ++i)
{
var delegateRefKind = delegateParameters[i].RefKind;
if (delegateRefKind != RefKind.None)
{
// Parameter {0} must be declared with the '{1}' keyword
Error(diagnostics, ErrorCode.ERR_BadParamRef, anonymousFunction.ParameterLocation(i),
i + 1, delegateRefKind.ToDisplayString());
}
}
return;
}
// See the comments in IsAnonymousFunctionCompatibleWithDelegate for an explanation of this one.
if (reason == LambdaConversionResult.StaticTypeInImplicitlyTypedLambda)
{
for (int i = 0; i < anonymousFunction.ParameterCount; ++i)
{
if (delegateParameters[i].Type.IsStatic)
{
// {0}: Static types cannot be used as parameter
Error(diagnostics, ErrorCode.ERR_ParameterIsStaticClass, anonymousFunction.ParameterLocation(i), delegateParameters[i].Type);
}
}
return;
}
// Otherwise, there might be a more complex reason why the parameter types are mismatched.
if (reason == LambdaConversionResult.MismatchedParameterType)
{
// Cannot convert {0} to delegate type '{1}' because the parameter types do not match the delegate parameter types
Error(diagnostics, ErrorCode.ERR_CantConvAnonMethParams, syntax, id, targetType);
Debug.Assert(anonymousFunction.ParameterCount == delegateParameters.Length);
for (int i = 0; i < anonymousFunction.ParameterCount; ++i)
{
var lambdaParameterType = anonymousFunction.ParameterType(i);
if (lambdaParameterType.IsErrorType())
{
continue;
}
var lambdaParameterLocation = anonymousFunction.ParameterLocation(i);
var lambdaRefKind = anonymousFunction.RefKind(i);
var delegateParameterType = delegateParameters[i].Type;
var delegateRefKind = delegateParameters[i].RefKind;
if (!lambdaParameterType.Equals(delegateParameterType, ignoreCustomModifiers: true, ignoreDynamic: true))
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(this.Compilation, lambdaParameterType, delegateParameterType);
// Parameter {0} is declared as type '{1}{2}' but should be '{3}{4}'
Error(diagnostics, ErrorCode.ERR_BadParamType, lambdaParameterLocation,
i + 1, lambdaRefKind.ToPrefix(), distinguisher.First, delegateRefKind.ToPrefix(), distinguisher.Second);
}
else if (lambdaRefKind != delegateRefKind)
{
if (delegateRefKind == RefKind.None)
{
// Parameter {0} should not be declared with the '{1}' keyword
Error(diagnostics, ErrorCode.ERR_BadParamExtraRef, lambdaParameterLocation, i + 1, lambdaRefKind.ToDisplayString());
}
else
{
// Parameter {0} must be declared with the '{1}' keyword
Error(diagnostics, ErrorCode.ERR_BadParamRef, lambdaParameterLocation, i + 1, delegateRefKind.ToDisplayString());
}
}
}
return;
}
if (reason == LambdaConversionResult.BindingFailed)
{
var bindingResult = anonymousFunction.Bind(delegateType);
Debug.Assert(ErrorFacts.PreventsSuccessfulDelegateConversion(bindingResult.Diagnostics));
diagnostics.AddRange(bindingResult.Diagnostics);
return;
}
// UNDONE: LambdaConversionResult.VoidExpressionLambdaMustBeStatementExpression:
Debug.Assert(false, "Missing case in lambda conversion error reporting");
}
protected static void GenerateImplicitConversionError(DiagnosticBag diagnostics, Compilation compilation, CSharpSyntaxNode syntax,
Conversion conversion, TypeSymbol sourceType, TypeSymbol targetType, ConstantValue sourceConstantValueOpt = null)
{
Debug.Assert(!conversion.IsImplicit || !conversion.IsValid);
// If the either type is an error then an error has already been reported
// for some aspect of the analysis of this expression. (For example, something like
// "garbage g = null; short s = g;" -- we don't want to report that g is not
// convertible to short because we've already reported that g does not have a good type.
if (!sourceType.IsErrorType() && !targetType.IsErrorType())
{
if (conversion.IsExplicit)
{
if (sourceType.SpecialType == SpecialType.System_Double && syntax.Kind() == SyntaxKind.NumericLiteralExpression &&
(targetType.SpecialType == SpecialType.System_Single || targetType.SpecialType == SpecialType.System_Decimal))
{
Error(diagnostics, ErrorCode.ERR_LiteralDoubleCast, syntax, (targetType.SpecialType == SpecialType.System_Single) ? "F" : "M", targetType);
}
else if (conversion.Kind == ConversionKind.ExplicitNumeric && sourceConstantValueOpt != null && sourceConstantValueOpt != ConstantValue.Bad &&
ConversionsBase.HasImplicitConstantExpressionConversion(new BoundLiteral(syntax, ConstantValue.Bad, sourceType), targetType))
{
// CLEVERNESS: By passing ConstantValue.Bad, we tell HasImplicitConstantExpressionConversion to ignore the constant
// value and only consider the types.
// If there would be an implicit constant conversion for a different constant of the same type
// (i.e. one that's not out of range), then it's more helpful to report the range check failure
// than to suggest inserting a cast.
Error(diagnostics, ErrorCode.ERR_ConstOutOfRange, syntax, sourceConstantValueOpt.Value, targetType);
}
else
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(compilation, sourceType, targetType);
Error(diagnostics, ErrorCode.ERR_NoImplicitConvCast, syntax, distinguisher.First, distinguisher.Second);
}
}
else if (conversion.ResultKind == LookupResultKind.OverloadResolutionFailure)
{
Debug.Assert(conversion.IsUserDefined);
ImmutableArray<MethodSymbol> originalUserDefinedConversions = conversion.OriginalUserDefinedConversions;
if (originalUserDefinedConversions.Length > 1)
{
Error(diagnostics, ErrorCode.ERR_AmbigUDConv, syntax, originalUserDefinedConversions[0], originalUserDefinedConversions[1], sourceType, targetType);
}
else
{
Debug.Assert(originalUserDefinedConversions.Length == 0,
"How can there be exactly one applicable user-defined conversion if the conversion doesn't exist?");
SymbolDistinguisher distinguisher = new SymbolDistinguisher(compilation, sourceType, targetType);
Error(diagnostics, ErrorCode.ERR_NoImplicitConv, syntax, distinguisher.First, distinguisher.Second);
}
}
else
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(compilation, sourceType, targetType);
Error(diagnostics, ErrorCode.ERR_NoImplicitConv, syntax, distinguisher.First, distinguisher.Second);
}
}
}
public Description(SymbolDistinguisher distinguisher, int index)
{
_distinguisher = distinguisher;
_index = index;
}
public Description(SymbolDistinguisher distinguisher, int index)
{
_distinguisher = distinguisher;
_index = index;
}
private BoundForEachStatement BindForEachPartsWorker(DiagnosticBag diagnostics, Binder originalBinder)
{
// Use the right binder to avoid seeing iteration variable
BoundExpression collectionExpr = originalBinder.GetBinder(_syntax.Expression).BindValue(_syntax.Expression, diagnostics, BindValueKind.RValue);
ForEachEnumeratorInfo.Builder builder = new ForEachEnumeratorInfo.Builder();
TypeSymbol inferredType;
bool hasErrors = !GetEnumeratorInfoAndInferCollectionElementType(ref builder, ref collectionExpr, diagnostics, out inferredType);
// These should only occur when special types are missing or malformed.
hasErrors = hasErrors ||
(object)builder.GetEnumeratorMethod == null ||
(object)builder.MoveNextMethod == null ||
(object)builder.CurrentPropertyGetter == null;
// Check for local variable conflicts in the *enclosing* binder; obviously the *current*
// binder has a local that matches!
var hasNameConflicts = originalBinder.ValidateDeclarationNameConflictsInScope(IterationVariable, diagnostics);
// If the type in syntax is "var", then the type should be set explicitly so that the
// Type property doesn't fail.
TypeSyntax typeSyntax = _syntax.Type;
bool isVar;
AliasSymbol alias;
TypeSymbol declType = BindType(typeSyntax, diagnostics, out isVar, out alias);
TypeSymbol iterationVariableType;
if (isVar)
{
iterationVariableType = inferredType ?? CreateErrorType("var");
}
else
{
Debug.Assert((object)declType != null);
iterationVariableType = declType;
}
BoundTypeExpression boundIterationVariableType = new BoundTypeExpression(typeSyntax, alias, iterationVariableType);
this.IterationVariable.SetTypeSymbol(iterationVariableType);
BoundStatement body = originalBinder.BindPossibleEmbeddedStatement(_syntax.Statement, diagnostics);
hasErrors = hasErrors || iterationVariableType.IsErrorType();
// Skip the conversion checks and array/enumerator differentiation if we know we have an error (except local name conflicts).
if (hasErrors)
{
return new BoundForEachStatement(
_syntax,
null, // can't be sure that it's complete
default(Conversion),
boundIterationVariableType,
this.IterationVariable,
collectionExpr,
body,
CheckOverflowAtRuntime,
this.BreakLabel,
this.ContinueLabel,
hasErrors);
}
hasErrors |= hasNameConflicts;
var foreachKeyword = _syntax.ForEachKeyword;
ReportDiagnosticsIfObsolete(diagnostics, builder.GetEnumeratorMethod, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.MoveNextMethod, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.CurrentPropertyGetter, foreachKeyword, hasBaseReceiver: false);
ReportDiagnosticsIfObsolete(diagnostics, builder.CurrentPropertyGetter.AssociatedSymbol, foreachKeyword, hasBaseReceiver: false);
// We want to convert from inferredType in the array/string case and builder.ElementType in the enumerator case,
// but it turns out that these are equivalent (when both are available).
HashSet<DiagnosticInfo> useSiteDiagnostics = null;
Conversion elementConversion = this.Conversions.ClassifyConversionForCast(inferredType, iterationVariableType, ref useSiteDiagnostics);
if (!elementConversion.IsValid)
{
ImmutableArray<MethodSymbol> originalUserDefinedConversions = elementConversion.OriginalUserDefinedConversions;
if (originalUserDefinedConversions.Length > 1)
{
diagnostics.Add(ErrorCode.ERR_AmbigUDConv, _syntax.ForEachKeyword.GetLocation(), originalUserDefinedConversions[0], originalUserDefinedConversions[1], inferredType, iterationVariableType);
}
else
{
SymbolDistinguisher distinguisher = new SymbolDistinguisher(this.Compilation, inferredType, iterationVariableType);
diagnostics.Add(ErrorCode.ERR_NoExplicitConv, _syntax.ForEachKeyword.GetLocation(), distinguisher.First, distinguisher.Second);
}
hasErrors = true;
}
else
{
ReportDiagnosticsIfObsolete(diagnostics, elementConversion, _syntax.ForEachKeyword, hasBaseReceiver: false);
}
// Spec (§8.8.4):
// If the type X of expression is dynamic then there is an implicit conversion from >>expression<< (not the type of the expression)
// to the System.Collections.IEnumerable interface (§6.1.8).
builder.CollectionConversion = this.Conversions.ClassifyConversionFromExpression(collectionExpr, builder.CollectionType, ref useSiteDiagnostics);
builder.CurrentConversion = this.Conversions.ClassifyConversion(builder.CurrentPropertyGetter.ReturnType, builder.ElementType, ref useSiteDiagnostics);
builder.EnumeratorConversion = this.Conversions.ClassifyConversion(builder.GetEnumeratorMethod.ReturnType, GetSpecialType(SpecialType.System_Object, diagnostics, _syntax), ref useSiteDiagnostics);
diagnostics.Add(_syntax.ForEachKeyword.GetLocation(), useSiteDiagnostics);
// Due to the way we extracted the various types, these conversions should always be possible.
// CAVEAT: if we're iterating over an array of pointers, the current conversion will fail since we
// can't convert from object to a pointer type. Similarly, if we're iterating over an array of
// Nullable<Error>, the current conversion will fail because we don't know if an ErrorType is a
// value type. This doesn't matter in practice, since we won't actually use the enumerator pattern
// when we lower the loop.
Debug.Assert(builder.CollectionConversion.IsValid);
Debug.Assert(builder.CurrentConversion.IsValid ||
(builder.ElementType.IsPointerType() && collectionExpr.Type.IsArray()) ||
(builder.ElementType.IsNullableType() && builder.ElementType.GetMemberTypeArgumentsNoUseSiteDiagnostics().Single().IsErrorType() && collectionExpr.Type.IsArray()));
Debug.Assert(builder.EnumeratorConversion.IsValid ||
this.Compilation.GetSpecialType(SpecialType.System_Object).TypeKind == TypeKind.Error ||
!useSiteDiagnostics.IsNullOrEmpty(),
"Conversions to object succeed unless there's a problem with the object type or the source type");
// If user-defined conversions could occur here, we would need to check for ObsoleteAttribute.
Debug.Assert((object)builder.CollectionConversion.Method == null,
"Conversion from collection expression to collection type should not be user-defined");
Debug.Assert((object)builder.CurrentConversion.Method == null,
"Conversion from Current property type to element type should not be user-defined");
Debug.Assert((object)builder.EnumeratorConversion.Method == null,
"Conversion from GetEnumerator return type to System.Object should not be user-defined");
// We're wrapping the collection expression in a (non-synthesized) conversion so that its converted
// type (i.e. builder.CollectionType) will be available in the binding API.
BoundConversion convertedCollectionExpression = new BoundConversion(
collectionExpr.Syntax,
collectionExpr,
builder.CollectionConversion,
CheckOverflowAtRuntime,
false,
ConstantValue.NotAvailable,
builder.CollectionType);
return new BoundForEachStatement(
_syntax,
builder.Build(this.Flags),
elementConversion,
boundIterationVariableType,
this.IterationVariable,
convertedCollectionExpression,
body,
CheckOverflowAtRuntime,
this.BreakLabel,
this.ContinueLabel,
hasErrors);
}
public Description(SymbolDistinguisher distinguisher, int index)
{
this.distinguisher = distinguisher;
this.index = index;
}
public Description(SymbolDistinguisher distinguisher, int index)
{
this.distinguisher = distinguisher;
this.index = index;
}
