/// <summary>
/// Infer the result type of the switch expression by looking for a common type.
/// </summary>
private TypeSymbol InferResultType(ImmutableArray <BoundSwitchExpressionArm> switchCases, DiagnosticBag diagnostics)
{
var seenTypes = PooledHashSet <TypeSymbol> .GetInstance();
var typesInOrder = ArrayBuilder <TypeSymbol> .GetInstance();
foreach (var @case in switchCases)
{
var type = @case.Value.Type;
if (!(type is null) && seenTypes.Add(type))
{
typesInOrder.Add(type);
}
}
HashSet <DiagnosticInfo> useSiteDiagnostics = null;
var commonType = BestTypeInferrer.GetBestType(typesInOrder, Conversions, ref useSiteDiagnostics);
diagnostics.Add(SwitchExpressionSyntax, useSiteDiagnostics);
if (commonType is null)
{
diagnostics.Add(ErrorCode.ERR_SwitchExpressionNoBestType, SwitchExpressionSyntax.Location);
commonType = CreateErrorType();
}
seenTypes.Free();
return(commonType);
}
/// <summary>
/// Infer the result type of the switch expression by looking for a common type
/// to which every arm's expression can be converted.
/// </summary>
private TypeSymbol?InferResultType(
ImmutableArray <BoundSwitchExpressionArm> switchCases,
BindingDiagnosticBag diagnostics
)
{
var seenTypes =
Symbols.SpecializedSymbolCollections.GetPooledSymbolHashSetInstance <TypeSymbol>();
var typesInOrder = ArrayBuilder <TypeSymbol> .GetInstance();
foreach (var @case in switchCases)
{
var type = @case.Value.Type;
if (type is object && seenTypes.Add(type))
{
typesInOrder.Add(type);
}
}
seenTypes.Free();
CompoundUseSiteInfo <AssemblySymbol> useSiteInfo = GetNewCompoundUseSiteInfo(
diagnostics
);
var commonType = BestTypeInferrer.GetBestType(
typesInOrder,
Conversions,
ref useSiteInfo
);
typesInOrder.Free();
// We've found a candidate common type among those arms that have a type. Also check that every arm's
// expression (even those without a type) can be converted to that type.
if (commonType is object)
{
foreach (var @case in switchCases)
{
if (
!this.Conversions.ClassifyImplicitConversionFromExpression(
@case.Value,
commonType,
ref useSiteInfo
).Exists
)
{
commonType = null;
break;
}
}
}
diagnostics.Add(SwitchExpressionSyntax, useSiteInfo);
return(commonType);
}
/// <summary>
/// Infer the result type of the switch expression by looking for a common type.
/// </summary>
private TypeSymbol InferResultType(ImmutableArray <BoundSwitchExpressionArm> switchCases, DiagnosticBag diagnostics)
{
var seenTypes = SpecializedCollections.GetPooledSymbolHashSetInstance <TypeSymbol>();
var typesInOrder = ArrayBuilder <TypeSymbol> .GetInstance();
foreach (var @case in switchCases)
{
var type = @case.Value.Type;
if (!(type is null) && seenTypes.Add(type))
{
typesInOrder.Add(type);
}
}
HashSet <DiagnosticInfo> useSiteDiagnostics = null;
var commonType = BestTypeInferrer.GetBestType(typesInOrder, Conversions, ref useSiteDiagnostics);
diagnostics.Add(SwitchExpressionSyntax, useSiteDiagnostics);
seenTypes.Free();
return(commonType);
}
public static TypeSymbol InferBestType(ImmutableArray<TypeSymbol> types, ConversionsBase conversions, ref HashSet<DiagnosticInfo> useSiteDiagnostics)
{
var inferrer = new BestTypeInferrer(conversions);
return inferrer.GetBestType(types, ref useSiteDiagnostics);
}
public static TypeSymbol InferBestType(ImmutableArray <TypeSymbol> types, Conversions conversions, ref HashSet <DiagnosticInfo> useSiteDiagnostics)
{
var inferrer = new BestTypeInferrer(conversions);
return(inferrer.GetBestType(types, ref useSiteDiagnostics));
}
