private void ResolveSignatureTypesInFunction(FunctionDeclarationSyntax function)
{
function.Type.BeginFulfilling();
var diagnosticCount = diagnostics.Count;
// Resolve the declaring type because we need its type for things like `self`
if (function.DeclaringType != null)
ResolveSignatureTypesInTypeDeclaration(function.DeclaringType);
var selfType = ResolveSelfType(function);
var resolver = new ExpressionTypeResolver(function.File, diagnostics, selfType);
if (function.GenericParameters != null)
ResolveTypesInGenericParameters(function.GenericParameters, resolver);
var parameterTypes = ResolveTypesInParameters(function, resolver);
var returnType = ResolveReturnType(function, resolver);
DataType functionType = new FunctionType(parameterTypes, returnType);
if (function.GenericParameters?.Any() ?? false)
functionType = new MetaFunctionType(function.GenericParameters.Select(p => p.Type.Fulfilled()), functionType);
function.Type.Fulfill(functionType);
if (diagnosticCount != diagnostics.Count) function.Poison();
}
public override void VisitVariableDeclarationStatement(VariableDeclarationStatementSyntax variableDeclaration, BindingScope bindingScope)
{
base.VisitVariableDeclarationStatement(variableDeclaration, bindingScope);
if (bindingScope.Lookup(variableDeclaration.Name, out var binding))
{
if (binding.MutableBinding)
{
diagnostics.Add(SemanticError.CantRebindMutableBinding(function.File, variableDeclaration.NameSpan));
function.Poison();
}
else if (variableDeclaration.MutableBinding)
{
diagnostics.Add(SemanticError.CantRebindAsMutableBinding(function.File, variableDeclaration.NameSpan));
function.Poison();
}
}
}
public override void VisitIdentifierName(IdentifierNameSyntax identifierName, bool lvalue)
{
if (!lvalue || identifierName.ReferencedSymbol.MutableBinding)
{
return;
}
diagnostics.Add(SemanticError.CantAssignToImmutable(function.File, identifierName.Span));
function.Poison();
}
private void CheckAssignment(DataType assignToType, ExpressionSyntax value)
{
if (assignToType is ReferenceType referenceType &&
referenceType.IsOwned)
{
if (value.ValueSemantics != ValueSemantics.Move)
{
diagnostics.Add(SemanticError.CantMove(function.File, value));
function.Poison();
}
}
}
private void ResolveBodyTypesInFunction(FunctionDeclarationSyntax function)
{
if (function.Body == null) return;
var diagnosticCount = diagnostics.Count;
// TODO the return types of constructors and init functions should probably be void for purposes of expressions
var resolver = new ExpressionTypeResolver(function.File, diagnostics, (Metatype)function.DeclaringType?.Type.Fulfilled(), function.ReturnType.Fulfilled());
// The body of a function shouldn't itself evaluate to anything.
// There should be no `=> value` for the block, so the type is `void`.
resolver.CheckExpressionType(function.Body, DataType.Void);
if (diagnosticCount != diagnostics.Count) function.Poison();
}