public IEnumerable <Decorator> GetMatches(FunctionSymbol symbol, IList <TypeSymbol> argumentTypes)
{
foreach (var overload in FunctionResolver.GetMatches(symbol, argumentTypes, out var _, out var _))
{
var decorator = this.TryGetDecorator(overload);
if (decorator != null)
{
yield return(decorator);
}
}
}
public IEnumerable <Decorator> GetMatches(FunctionSymbol symbol, IList <TypeSymbol> argumentTypes)
{
if (!functionSymbols.Contains(symbol))
{
yield break;
}
foreach (var overload in FunctionResolver.GetMatches(symbol, argumentTypes, out var _, out var _))
{
this.decoratorsByOverloads.TryGetValue(overload, out Decorator? decorator);
if (decorator != null)
{
yield return(decorator);
}
}
}
private TypeSymbol GetFunctionSymbolType(
FunctionCallSyntax syntax,
FunctionSymbol function,
ImmutableArray <FunctionArgumentSyntax> argumentSyntaxes,
IList <TypeSymbol> argumentTypes,
IList <ErrorDiagnostic> errors)
{
// Recover argument type errors so we can continue type checking for the parent function call.
var recoveredArgumentTypes = argumentTypes
.Select(t => t.TypeKind == TypeKind.Error ? LanguageConstants.Any : t)
.ToList();
var matches = FunctionResolver.GetMatches(
function,
recoveredArgumentTypes,
out IList <ArgumentCountMismatch> countMismatches,
out IList <ArgumentTypeMismatch> typeMismatches).ToList();
if (matches.Count == 0)
{
if (typeMismatches.Any())
{
if (typeMismatches.Count > 1 && typeMismatches.Skip(1).All(tm => tm.ArgumentIndex == typeMismatches[0].ArgumentIndex))
{
// All type mismatches are equally good (or bad).
var parameterTypes = typeMismatches.Select(tm => tm.ParameterType).ToList();
var argumentType = typeMismatches[0].ArgumentType;
var signatures = typeMismatches.Select(tm => tm.Source.TypeSignature).ToList();
var argumentSyntax = argumentSyntaxes[typeMismatches[0].ArgumentIndex];
errors.Add(DiagnosticBuilder.ForPosition(argumentSyntax).CannotResolveFunctionOverload(signatures, argumentType, parameterTypes));
}
else
{
// Choose the type mismatch that has the largest index as the best one.
var(_, argumentIndex, argumentType, parameterType) = typeMismatches.OrderBy(tm => tm.ArgumentIndex).Last();
errors.Add(DiagnosticBuilder.ForPosition(argumentSyntaxes[argumentIndex]).ArgumentTypeMismatch(argumentType, parameterType));
}
}
else
{
// Argument type mismatch wins over count mismatch. Handle count mismatch only when there's no type mismatch.
var(actualCount, mininumArgumentCount, maximumArgumentCount) = countMismatches.Aggregate(ArgumentCountMismatch.Reduce);
var argumentsSpan = TextSpan.Between(syntax.OpenParen, syntax.CloseParen);
errors.Add(DiagnosticBuilder.ForPosition(argumentsSpan).ArgumentCountMismatch(actualCount, mininumArgumentCount, maximumArgumentCount));
}
}
if (errors.Any())
{
return(new ErrorTypeSymbol(errors));
}
if (matches.Count == 1)
{
// we have an exact match or a single ambiguous match
// return its type
return(matches.Single().ReturnType);
}
// function arguments are ambiguous (due to "any" type)
// technically, the correct behavior would be to return a union of all possible types
// unfortunately our language lacks a good type checking construct
// and we also don't want users to have to use the converter functions to work around it
// instead, we will return the "any" type to short circuit the type checking for those cases
return(LanguageConstants.Any);
}
