public override VoidObject VisitVarStmt(Stmt.Var stmt)
{
bool sanityCheckFailed = false;
// Sanity check the input to ensure that we don't get NullReferenceExceptions later on
if (stmt.TypeReference == null)
{
TypeValidationErrorCallback(new TypeValidationError(
stmt.Name,
$"Internal compiler error: {stmt.Name.Lexeme} is missing a TypeReference"
));
sanityCheckFailed = true;
}
if (stmt.Initializer != null && !stmt.Initializer.TypeReference.IsResolved)
{
TypeValidationErrorCallback(new TypeValidationError(
stmt.Name,
$"Internal compiler error: var {stmt.Name.Lexeme} initializer {stmt.Initializer} inference has not been attempted"
));
sanityCheckFailed = true;
}
if (sanityCheckFailed)
{
return(VoidObject.Void);
}
if (stmt.TypeReference !.IsResolved)
{
if (stmt.Initializer != null)
{
if (stmt.TypeReference.IsNullObject && stmt.Initializer.TypeReference.IsNullObject)
{
// TODO: Use stmt.Initializer.Token here instead of stmt.name, #189
TypeValidationErrorCallback(new TypeValidationError(
stmt.Name,
"Cannot assign null to an implicitly typed local variable"
));
}
else if (!TypeCoercer.CanBeCoercedInto(stmt.TypeReference, stmt.Initializer.TypeReference, ((stmt.Initializer as Expr.Literal)?.Value as INumericLiteral)?.BitsUsed))
{
// TODO: Use stmt.Initializer.Token here instead of stmt.name, #189
TypeValidationErrorCallback(new TypeValidationError(
stmt.Name,
$"Cannot assign {stmt.Initializer.TypeReference.ClrType.ToTypeKeyword()} to {stmt.TypeReference.ClrType.ToTypeKeyword()} variable"
));
}
else if (stmt.Initializer.TypeReference.IsNullObject)
{
// TODO: Use stmt.Initializer.Token here instead of stmt.name, #189
compilerWarningCallback(new CompilerWarning("Initializing variable to null detected", stmt.Name, WarningType.NULL_USAGE));
}
}
}
private void VisitCallExprForGetCallee(Expr.Call call, Expr.Get get)
{
string methodName = get.Name.Lexeme;
if (get.Methods.Length == 0)
{
if (!get.Object.TypeReference.IsResolved)
{
// This is a bit of an oddball, but... We get here when an attempt is made to call a method on some
// undefined type. (`Foo.do_stuff`)
//
// Now, this is a compile-time error, but the problem is that it's handled by this class itself;
// encountering this error will not abort the tree traversal so we must avoid breaking it.
}
else
{
// This is even more odd, but we must ensure that we have well-defined semantics in the weird case
// where this would happen.
TypeValidationErrorCallback(new TypeValidationError(
call.Paren,
$"Internal compiler error: no methods with name '{methodName}' could be found. This is a critical " +
$"error that should have aborted the compilation before the {nameof(TypesResolvedValidator)} " +
"validation is started. "
));
}
}
else if (get.Methods.Length == 1)
{
MethodInfo method = get.Methods.Single();
var parameters = method.GetParameters();
// There is exactly one potential method to call in this case. We use this fact to provide better
// error messages to the caller than when calling an overloaded method.
if (parameters.Length != call.Arguments.Count)
{
TypeValidationErrorCallback(new TypeValidationError(
call.Paren,
$"Method '{methodName}' has {parameters.Length} parameter(s) but was called with {call.Arguments.Count} argument(s)"
));
return;
}
for (int i = 0; i < call.Arguments.Count; i++)
{
ParameterInfo parameter = parameters[i];
Expr argument = call.Arguments[i];
if (!argument.TypeReference.IsResolved)
{
throw new PerlangInterpreterException(
$"Internal compiler error: Argument '{argument}' to function {methodName} not resolved");
}
// FIXME: call.Token is a bit off here; it would be useful when constructing compiler warnings based
// on this if we could provide the token for the argument expression instead. However, the Expr type
// as used by 'argument' is a non-token-based expression so this is currently impossible.
// FIXME: `null` here has disadvantages as described elsewhere.
if (!TypeCoercer.CanBeCoercedInto(parameter.ParameterType, argument.TypeReference.ClrType, null))
{
// Very likely refers to a native method, where parameter names are not available at this point.
TypeValidationErrorCallback(new TypeValidationError(
argument.TypeReference.TypeSpecifier !,
$"Cannot pass {argument.TypeReference.ClrType.ToTypeKeyword()} argument as {parameter.ParameterType.ToTypeKeyword()} parameter to {methodName}()"));
}
}
}
else
{
// Method is overloaded. Try to resolve the best match we can find.
foreach (MethodInfo method in get.Methods)
{
var parameters = method.GetParameters();
if (parameters.Length != call.Arguments.Count)
{
// The number of parameters do not match, so this method will never be a suitable candidate
// for our expression.
continue;
}
bool coercionsFailed = false;
for (int i = 0; i < call.Arguments.Count; i++)
{
ParameterInfo parameter = parameters[i];
Expr argument = call.Arguments[i];
if (!argument.TypeReference.IsResolved)
{
throw new PerlangInterpreterException(
$"Internal compiler error: Argument '{argument}' to method {methodName} not resolved");
}
// FIXME: The same caveat as above with call.Token applies here as well.
if (!TypeCoercer.CanBeCoercedInto(parameter.ParameterType, argument.TypeReference.ClrType, null))
{
coercionsFailed = true;
break;
}
}
if (!coercionsFailed)
{
// We have found a suitable overload to use. Update the expression
get.Methods = ImmutableArray.Create(method);
return;
}
}
TypeValidationErrorCallback(new NameResolutionTypeValidationError(
call.Paren,
$"Method '{call.CalleeToString}' found, but no overload matches the provided parameters."
));
}
}
private void VisitCallExprForOtherCallee(Expr.Call expr)
{
Binding binding = GetVariableOrFunctionCallback(expr);
if (binding == null)
{
TypeValidationErrorCallback(
new NameResolutionTypeValidationError(expr.Paren, $"Attempting to call undefined function '{expr.CalleeToString}'")
);
return;
}
IList <Parameter> parameters;
string functionName;
switch (binding)
{
case FunctionBinding functionBinding:
Stmt.Function function = functionBinding.Function;
if (function == null)
{
throw new NameResolutionTypeValidationError(expr.Paren, $"Internal compiler error: function for {expr} not expected to be null");
}
parameters = function.Parameters;
functionName = function.Name.Lexeme;
break;
default:
throw new NameResolutionTypeValidationError(expr.Paren, $"Attempting to call invalid function {binding} using {expr}");
}
if (parameters.Count != expr.Arguments.Count)
{
TypeValidationErrorCallback(new TypeValidationError(
expr.Paren,
$"Function '{functionName}' has {parameters.Count} parameter(s) but was called with {expr.Arguments.Count} argument(s)")
);
return;
}
for (int i = 0; i < expr.Arguments.Count; i++)
{
Parameter parameter = parameters[i];
Expr argument = expr.Arguments[i];
if (!argument.TypeReference.IsResolved)
{
throw new PerlangInterpreterException($"Internal compiler error: Argument '{argument}' to function {functionName} not resolved");
}
if (argument.TypeReference.IsNullObject)
{
compilerWarningCallback(new CompilerWarning($"Null parameter detected for '{parameter.Name.Lexeme}'", expr.TokenAwareCallee.Token, WarningType.NULL_USAGE));
}
// FIXME: expr.Token is an approximation here as well (see other similar comments in this file)
// FIXME: `null` here means that small-constants of e.g. `long` will not be able to be passed as `int` parameters.
if (!TypeCoercer.CanBeCoercedInto(parameter.TypeReference, argument.TypeReference, null))
{
if (parameter.Name != null)
{
TypeValidationErrorCallback(new TypeValidationError(
argument.TypeReference.TypeSpecifier !,
$"Cannot pass {argument.TypeReference.ClrType.ToTypeKeyword()} argument as parameter '{parameter.Name.Lexeme}: {parameter.TypeReference.ClrType.ToTypeKeyword()}' to {functionName}()"));
}
else
{
// Very likely refers to a native method, where parameter names are not available at this point.
TypeValidationErrorCallback(new TypeValidationError(
argument.TypeReference.TypeSpecifier !,
$"Cannot pass {argument.TypeReference.ClrType.ToTypeKeyword()} argument as {parameter.TypeReference.ClrType.ToTypeKeyword()} parameter to {functionName}()"));
}
}
}
}
