bool literal_is(ast_t* ast, pass_opt_t* opt)
{
pony_assert(ast != NULL);
pony_assert(ast_id(ast) == TK_IS || ast_id(ast) == TK_ISNT);
AST_GET_CHILDREN(ast, left, right);
ast_t* l_type = ast_type(left);
ast_t* r_type = ast_type(right);
if(is_typecheck_error(l_type) || is_typecheck_error(r_type))
return false;
if(!is_type_literal(l_type) && !is_type_literal(r_type))
// No literals here.
return true;
if(is_type_literal(l_type) && !is_type_literal(r_type))
{
// Coerce left to type of right.
return coerce_literals(&left, r_type, opt);
}
if(!is_type_literal(l_type) && is_type_literal(r_type))
{
// Coerce right to type of left.
return coerce_literals(&right, l_type, opt);
}
// Both sides are literals, that's a problem.
pony_assert(is_type_literal(l_type));
pony_assert(is_type_literal(r_type));
ast_error(opt->check.errors, ast, "Cannot infer type of operands");
return false;
}
bool expr_field(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, id, type, init);
if(ast_id(init) != TK_NONE)
{
// Initialiser type must match declared type.
if(!coerce_literals(&init, type, opt))
return false;
ast_t* init_type = ast_type(init);
if(is_typecheck_error(init_type))
return false;
init_type = alias(init_type);
if(!is_subtype(init_type, type))
{
ast_error(init,
"field/param initialiser is not a subtype of the field/param type");
ast_error(type, "field/param type: %s", ast_print_type(type));
ast_error(init, "initialiser type: %s", ast_print_type(init_type));
ast_free_unattached(init_type);
return false;
}
ast_free_unattached(init_type);
}
ast_settype(ast, type);
return true;
}
bool expr_param(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, id, type, init);
ast_settype(ast, type);
bool ok = true;
if(ast_id(init) != TK_NONE)
{
// Initialiser type must match declared type.
if(!coerce_literals(&init, type, opt))
return false;
ast_t* init_type = ast_type(init);
if(is_typecheck_error(init_type))
return false;
init_type = alias(init_type);
errorframe_t err = NULL;
if(!is_subtype(init_type, type, &err, opt))
{
errorframe_t err2 = NULL;
ast_error_frame(&err2, init,
"default argument is not a subtype of the parameter type");
errorframe_append(&err2, &err);
errorframe_report(&err2, opt->check.errors);
ok = false;
}
ast_free_unattached(init_type);
}
return ok;
}
bool expr_field(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, id, type, init);
// An embedded field must have a known, non-actor type.
if(ast_id(ast) == TK_EMBED)
{
if(!is_known(type) || is_actor(type))
{
ast_error(ast, "embedded fields must always be primitives or classes");
return false;
}
}
if(ast_id(init) != TK_NONE)
{
// Initialiser type must match declared type.
if(!coerce_literals(&init, type, opt))
return false;
ast_t* init_type = ast_type(init);
if(is_typecheck_error(init_type))
return false;
init_type = alias(init_type);
if(!is_subtype(init_type, type))
{
ast_error(init,
"field/param initialiser is not a subtype of the field/param type");
ast_error(type, "field/param type: %s", ast_print_type(type));
ast_error(init, "initialiser type: %s", ast_print_type(init_type));
ast_free_unattached(init_type);
return false;
}
// If it's an embedded field, check for a constructor result.
if(ast_id(ast) == TK_EMBED)
{
if((ast_id(init) != TK_CALL) ||
(ast_id(ast_childidx(init, 2)) != TK_NEWREF))
{
ast_error(ast,
"an embedded field must be initialised using a constructor");
return false;
}
}
ast_free_unattached(init_type);
}
ast_settype(ast, type);
return true;
}
bool expr_fun(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
AST_GET_CHILDREN(ast,
cap, id, typeparams, params, type, can_error, body);
if(ast_id(body) == TK_NONE)
return true;
if(!coerce_literals(&body, type, opt))
return false;
bool is_trait =
(ast_id(t->frame->type) == TK_TRAIT) ||
(ast_id(t->frame->type) == TK_INTERFACE) ||
(ast_id((ast_t*)ast_data(ast)) == TK_TRAIT) ||
(ast_id((ast_t*)ast_data(ast)) == TK_INTERFACE);
// Check partial functions.
if(ast_id(can_error) == TK_QUESTION)
{
// If a partial function, check that we might actually error.
if(!is_trait && !ast_canerror(body))
{
ast_error(can_error, "function body is not partial but the function is");
return false;
}
} else {
// If not a partial function, check that we can't error.
if(ast_canerror(body))
{
ast_error(can_error, "function body is partial but the function is not");
show_partiality(body);
return false;
}
}
if(!check_primitive_init(t, ast) || !check_finaliser(ast))
return false;
switch(ast_id(ast))
{
case TK_NEW:
return check_fields_defined(ast) && check_main_create(t, ast);
case TK_FUN:
return check_return_type(ast);
default:
{}
}
return true;
}
// Infer the types of any literals in the pattern of the given case
static bool infer_pattern_type(ast_t* pattern, ast_t* match_expr_type,
pass_opt_t* opt)
{
assert(pattern != NULL);
assert(match_expr_type != NULL);
if(is_type_literal(match_expr_type))
{
ast_error(match_expr_type,
"cannot infer type for literal match expression");
return false;
}
return coerce_literals(&pattern, match_expr_type, opt);
}
bool expr_field(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, id, type, init);
if(ast_id(init) != TK_NONE)
{
// Only parameters have initialisers. Field initialisers are moved into
// constructors in the sugar pass.
assert(ast_id(ast) == TK_PARAM);
// Initialiser type must match declared type.
if(!coerce_literals(&init, type, opt))
return false;
ast_t* init_type = ast_type(init);
if(is_typecheck_error(init_type))
return false;
init_type = alias(init_type);
errorframe_t info = NULL;
if(!is_subtype(init_type, type, &info))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, init,
"default argument is not a subtype of the parameter type");
ast_error_frame(&frame, type, "parameter type: %s",
ast_print_type(type));
ast_error_frame(&frame, init, "default argument type: %s",
ast_print_type(init_type));
errorframe_append(&frame, &info);
errorframe_report(&frame);
ast_free_unattached(init_type);
return false;
}
ast_free_unattached(init_type);
}
ast_settype(ast, type);
return true;
}
bool expr_fun(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, cap, id, typeparams, params, type, can_error, body);
if(ast_id(body) == TK_NONE)
return true;
if(!coerce_literals(&body, type, opt))
return false;
switch(ast_id(ast))
{
case TK_NEW:
{
bool ok = true;
if(is_machine_word(type))
{
if(!check_return_type(opt, ast))
ok = false;
}
if(!check_fields_defined(opt, ast))
ok = false;
return ok;
}
case TK_FUN:
return check_return_type(opt, ast);
default: {}
}
return true;
}
bool literal_call(ast_t* ast, pass_opt_t* options)
{
assert(ast != NULL);
assert(ast_id(ast) == TK_CALL);
AST_GET_CHILDREN(ast, positional_args, named_args, receiver);
ast_t* recv_type = ast_type(receiver);
if(is_typecheck_error(recv_type))
return false;
if(ast_id(recv_type) == TK_LITERAL)
{
ast_error(ast, "Cannot call a literal");
return false;
}
if(ast_id(recv_type) != TK_OPERATORLITERAL) // Nothing to do
return true;
lit_op_info_t* op = (lit_op_info_t*)ast_data(recv_type);
assert(op != NULL);
if(ast_childcount(named_args) != 0)
{
ast_error(named_args, "Cannot use named arguments with literal operator");
return false;
}
ast_t* arg = ast_child(positional_args);
if(arg != NULL)
{
if(!unify(arg, options, true))
return false;
ast_t* arg_type = ast_type(arg);
if(is_typecheck_error(arg_type))
return false;
if(ast_id(arg_type) != TK_LITERAL) // Apply argument type to receiver
return coerce_literals(&receiver, arg_type, options);
if(!op->can_propogate_literal)
{
ast_error(ast, "Cannot infer operand type");
return false;
}
}
size_t arg_count = ast_childcount(positional_args);
if(op->arg_count != arg_count)
{
ast_error(ast, "Invalid number of arguments to literal operator");
return false;
}
make_literal_type(ast);
return true;
}
bool expr_fun(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
AST_GET_CHILDREN(ast,
cap, id, typeparams, params, type, can_error, body);
if(ast_id(body) == TK_NONE)
return true;
if(!coerce_literals(&body, type, opt))
return false;
bool is_trait =
(ast_id(t->frame->type) == TK_TRAIT) ||
(ast_id(t->frame->type) == TK_INTERFACE) ||
(ast_id((ast_t*)ast_data(ast)) == TK_TRAIT) ||
(ast_id((ast_t*)ast_data(ast)) == TK_INTERFACE);
// Check partial functions.
if(ast_id(can_error) == TK_QUESTION)
{
// If a partial function, check that we might actually error.
ast_t* body_type = ast_type(body);
if(body_type == NULL)
{
// An error has already occurred.
assert(get_error_count() > 0);
return false;
}
if(!is_trait &&
!ast_canerror(body) &&
(ast_id(body_type) != TK_COMPILE_INTRINSIC))
{
ast_error(can_error, "function body is not partial but the function is");
return false;
}
} else {
// If not a partial function, check that we can't error.
if(ast_canerror(body))
{
ast_error(can_error, "function body is partial but the function is not");
show_partiality(body);
return false;
}
}
if(!check_primitive_init(t, ast) || !check_finaliser(t, ast))
return false;
switch(ast_id(ast))
{
case TK_NEW:
{
bool ok = true;
if(is_machine_word(type))
{
if(!check_return_type(ast))
ok = false;
}
if(!check_fields_defined(ast))
ok = false;
if(!check_main_create(t, ast))
ok = false;
return ok;
}
case TK_FUN:
return check_return_type(ast);
default: {}
}
return true;
}
// Process the given capture and create the AST for the corresponding field.
// Returns the create field AST, which must be freed by the caller.
// Returns NULL on error.
static ast_t* make_capture_field(pass_opt_t* opt, ast_t* capture)
{
assert(capture != NULL);
AST_GET_CHILDREN(capture, id_node, type, value);
const char* name = ast_name(id_node);
// There are 3 varieties of capture:
// x -> capture variable x, type from defn of x
// x = y -> capture expression y, type inferred from expression type
// x: T = y -> capture expression y, type T
if(ast_id(value) == TK_NONE)
{
// Variable capture
assert(ast_id(type) == TK_NONE);
ast_t* def = ast_get(capture, name, NULL);
if(def == NULL)
{
ast_error(opt->check.errors, id_node,
"cannot capture \"%s\", variable not defined", name);
return NULL;
}
token_id def_id = ast_id(def);
if(def_id != TK_ID && def_id != TK_FVAR && def_id != TK_FLET &&
def_id != TK_PARAM)
{
ast_error(opt->check.errors, id_node, "cannot capture \"%s\", can only "
"capture fields, parameters and local variables", name);
return NULL;
}
BUILD(capture_rhs, id_node, NODE(TK_REFERENCE, ID(name)));
type = alias(ast_type(def));
value = capture_rhs;
} else if(ast_id(type) == TK_NONE) {
// No type specified, use type of the captured expression
type = alias(ast_type(value));
} else {
// Type given, infer literals
if(!coerce_literals(&value, type, opt))
return NULL;
}
if(is_typecheck_error(type))
return NULL;
type = sanitise_type(type);
BUILD(field, id_node,
NODE(TK_FVAR,
TREE(id_node)
TREE(type)
TREE(value)
NONE)); // Delegate type
return field;
}
bool expr_return(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
// return is always the last expression in a sequence
assert(ast_sibling(ast) == NULL);
if(ast_parent(ast) == t->frame->method_body)
{
ast_error(ast,
"use return only to exit early from a method, not at the end");
return false;
}
ast_t* type = ast_childidx(t->frame->method, 4);
ast_t* body = ast_child(ast);
if(!coerce_literals(&body, type, opt))
return false;
ast_t* body_type = ast_type(body);
if(is_typecheck_error(body_type))
return false;
if(is_control_type(body_type))
{
ast_error(body, "return value cannot be a control statement");
return false;
}
bool ok = true;
switch(ast_id(t->frame->method))
{
case TK_NEW:
if(is_this_incomplete(t, ast))
{
ast_error(ast,
"all fields must be defined before constructor returns");
ok = false;
}
break;
case TK_BE:
assert(is_none(body_type));
break;
default:
{
// The body type must be a subtype of the return type, and an alias of
// the body type must be a subtype of an alias of the return type.
ast_t* a_type = alias(type);
ast_t* a_body_type = alias(body_type);
errorframe_t info = NULL;
if(!is_subtype(body_type, type, &info) ||
!is_subtype(a_body_type, a_type, &info))
{
errorframe_t frame = NULL;
ast_t* last = ast_childlast(body);
ast_error_frame(&frame, last, "returned value isn't the return type");
ast_error_frame(&frame, type, "function return type: %s",
ast_print_type(type));
ast_error_frame(&frame, body_type, "returned value type: %s",
ast_print_type(body_type));
errorframe_append(&frame, &info);
errorframe_report(&frame);
ok = false;
}
ast_free_unattached(a_type);
ast_free_unattached(a_body_type);
}
}
ast_settype(ast, ast_from(ast, TK_RETURN));
ast_inheritflags(ast);
return ok;
}
// Process the given capture and create the AST for the corresponding field.
// Returns the create field AST in out_field, which must be freed by the caller,
// or NULL if there is no field to create.
// Returns false on error.
static bool make_capture_field(pass_opt_t* opt, ast_t* capture,
ast_t** out_field)
{
pony_assert(capture != NULL);
pony_assert(out_field != NULL);
AST_GET_CHILDREN(capture, id_node, type, value);
const char* name = ast_name(id_node);
bool is_dontcare = is_name_dontcare(name);
// There are 3 varieties of capture:
// x -> capture variable x, type from defn of x
// x = y -> capture expression y, type inferred from expression type
// x: T = y -> capture expression y, type T
if(ast_id(value) == TK_NONE)
{
// Variable capture
pony_assert(ast_id(type) == TK_NONE);
if(is_dontcare)
{
*out_field = NULL;
return true;
}
ast_t* def = ast_get(capture, name, NULL);
if(def == NULL)
{
ast_error(opt->check.errors, id_node,
"cannot capture \"%s\", variable not defined", name);
return false;
}
// lambda captures used before their declaration with their type
// not defined are not legal
if(!def_before_use(opt, def, capture, name))
return false;
switch(ast_id(def))
{
case TK_VAR:
case TK_LET:
case TK_PARAM:
case TK_MATCH_CAPTURE:
case TK_FVAR:
case TK_FLET:
case TK_EMBED:
break;
default:
ast_error(opt->check.errors, id_node, "cannot capture \"%s\", can only "
"capture fields, parameters and local variables", name);
return false;
}
BUILD(capture_rhs, id_node, NODE(TK_REFERENCE, ID(name)));
type = alias(ast_type(def));
value = capture_rhs;
} else if(ast_id(type) == TK_NONE) {
// No type specified, use type of the captured expression
if(ast_type(value) == NULL)
return false;
type = alias(ast_type(value));
} else {
// Type given, infer literals
if(!coerce_literals(&value, type, opt))
return false;
// Check subtyping now if we're capturing into '_', since the field will be
// discarded.
if(is_dontcare)
{
ast_t* v_type = alias(ast_type(value));
errorframe_t info = NULL;
if(!is_subtype(v_type, type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, value, "argument not a subtype of parameter");
errorframe_append(&frame, &info);
errorframe_report(&frame, opt->check.errors);
ast_free_unattached(v_type);
return false;
}
ast_free_unattached(v_type);
}
}
if(is_typecheck_error(type))
return false;
if(is_dontcare)
{
*out_field = NULL;
return true;
}
type = sanitise_type(type);
BUILD(field, id_node,
NODE(TK_FVAR,
TREE(id_node)
TREE(type)
TREE(value)));
*out_field = field;
return true;
}
static bool check_arg_types(pass_opt_t* opt, ast_t* params, ast_t* positional,
bool incomplete, bool partial)
{
// Check positional args vs params.
ast_t* param = ast_child(params);
ast_t* arg = ast_child(positional);
while(arg != NULL)
{
if(ast_id(arg) == TK_NONE)
{
if(partial)
{
// Don't check missing arguments for partial application.
arg = ast_sibling(arg);
param = ast_sibling(param);
continue;
} else {
// Pick up a default argument if we can.
if(!apply_default_arg(opt, param, arg))
return false;
}
}
ast_t* p_type = ast_childidx(param, 1);
if(!coerce_literals(&arg, p_type, opt))
return false;
ast_t* arg_type = ast_type(arg);
if(is_typecheck_error(arg_type))
return false;
if(is_control_type(arg_type))
{
ast_error(opt->check.errors, arg,
"can't use a control expression in an argument");
return false;
}
ast_t* a_type = alias(arg_type);
if(incomplete)
{
ast_t* expr = arg;
if(ast_id(arg) == TK_SEQ)
expr = ast_child(arg);
// If 'this' is incomplete and the arg is 'this', change the type to tag.
if((ast_id(expr) == TK_THIS) && (ast_sibling(expr) == NULL))
{
ast_t* tag_type = set_cap_and_ephemeral(a_type, TK_TAG, TK_NONE);
ast_free_unattached(a_type);
a_type = tag_type;
}
}
errorframe_t info = NULL;
if(!is_subtype(a_type, p_type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, arg, "argument not a subtype of parameter");
errorframe_append(&frame, &info);
errorframe_report(&frame, opt->check.errors);
ast_free_unattached(a_type);
return false;
}
ast_free_unattached(a_type);
arg = ast_sibling(arg);
param = ast_sibling(param);
}
return true;
}
bool expr_assign(pass_opt_t* opt, ast_t* ast)
{
// Left and right are swapped in the AST to make sure we type check the
// right side before the left. Fetch them in the opposite order.
assert(ast != NULL);
AST_GET_CHILDREN(ast, right, left);
ast_t* l_type = ast_type(left);
if(l_type == NULL || !is_lvalue(opt, left, is_result_needed(ast)))
{
ast_error(opt->check.errors, ast,
"left side must be something that can be assigned to");
return false;
}
if(!coerce_literals(&right, l_type, opt))
return false;
ast_t* r_type = ast_type(right);
if(is_typecheck_error(r_type))
return false;
if(is_control_type(r_type))
{
ast_error(opt->check.errors, ast,
"the right hand side does not return a value");
return false;
}
if(!infer_locals(opt, left, r_type))
return false;
// Inferring locals may have changed the left type.
l_type = ast_type(left);
// Assignment is based on the alias of the right hand side.
ast_t* a_type = alias(r_type);
errorframe_t info = NULL;
if(!is_subtype(a_type, l_type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, ast, "right side must be a subtype of left side");
errorframe_append(&frame, &info);
errorframe_report(&frame, opt->check.errors);
ast_free_unattached(a_type);
return false;
}
if((ast_id(left) == TK_TUPLE) && (ast_id(a_type) != TK_TUPLETYPE))
{
switch(ast_id(a_type))
{
case TK_UNIONTYPE:
ast_error(opt->check.errors, ast,
"can't destructure a union using assignment, use pattern matching "
"instead");
break;
case TK_ISECTTYPE:
ast_error(opt->check.errors, ast,
"can't destructure an intersection using assignment, use pattern "
"matching instead");
break;
default:
assert(0);
break;
}
ast_free_unattached(a_type);
return false;
}
bool ok_safe = safe_to_write(left, a_type);
if(!ok_safe)
{
if(ast_id(left) == TK_FVARREF && ast_child(left) != NULL &&
ast_id(ast_child(left)) == TK_THIS)
{
// We are writing to a field in this
ast_t* fn = ast_nearest(left, TK_FUN);
if(fn != NULL)
{
ast_t* iso = ast_child(fn);
assert(iso != NULL);
token_id iso_id = ast_id(iso);
if(iso_id == TK_BOX || iso_id == TK_VAL || iso_id == TK_TAG)
{
ast_error(opt->check.errors, ast,
"cannot write to a field in a %s function. If you are trying to "
"change state in a function use fun ref",
lexer_print(iso_id));
ast_free_unattached(a_type);
return false;
}
}
}
ast_error(opt->check.errors, ast,
"not safe to write right side to left side");
ast_error_continue(opt->check.errors, a_type, "right side type: %s",
ast_print_type(a_type));
ast_free_unattached(a_type);
return false;
}
ast_free_unattached(a_type);
if(!check_embed_construction(opt, left, right))
return false;
ast_settype(ast, consume_type(l_type, TK_NONE));
return true;
}
static ast_result_t declared_ffi(pass_opt_t* opt, ast_t* call, ast_t* decl)
{
assert(call != NULL);
assert(decl != NULL);
assert(ast_id(decl) == TK_FFIDECL);
AST_GET_CHILDREN(call, call_name, call_ret_typeargs, args, named_args,
call_error);
AST_GET_CHILDREN(decl, decl_name, decl_ret_typeargs, params, named_params,
decl_error);
// Check args vs params
ast_t* param = ast_child(params);
ast_t* arg = ast_child(args);
while((arg != NULL) && (param != NULL) && ast_id(param) != TK_ELLIPSIS)
{
ast_t* p_type = ast_childidx(param, 1);
if(!coerce_literals(&arg, p_type, opt))
return AST_ERROR;
ast_t* a_type = ast_type(arg);
errorframe_t info = NULL;
if((a_type != NULL) &&
!void_star_param(p_type, a_type) &&
!is_subtype(a_type, p_type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, arg, "argument not a subtype of parameter");
ast_error_frame(&frame, param, "parameter type: %s",
ast_print_type(p_type));
ast_error_frame(&frame, arg, "argument type: %s",
ast_print_type(a_type));
errorframe_append(&frame, &info);
errorframe_report(&frame, opt->check.errors);
return AST_ERROR;
}
arg = ast_sibling(arg);
param = ast_sibling(param);
}
if(arg != NULL && param == NULL)
{
ast_error(opt->check.errors, arg, "too many arguments");
return AST_ERROR;
}
if(param != NULL && ast_id(param) != TK_ELLIPSIS)
{
ast_error(opt->check.errors, named_args, "too few arguments");
return AST_ERROR;
}
for(; arg != NULL; arg = ast_sibling(arg))
{
ast_t* a_type = ast_type(arg);
if((a_type != NULL) && is_type_literal(a_type))
{
ast_error(opt->check.errors, arg,
"Cannot pass number literals as unchecked FFI arguments");
return AST_ERROR;
}
}
// Check return types
ast_t* call_ret_type = ast_child(call_ret_typeargs);
ast_t* decl_ret_type = ast_child(decl_ret_typeargs);
errorframe_t info = NULL;
if((call_ret_type != NULL) &&
!is_eqtype(call_ret_type, decl_ret_type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, call_ret_type,
"call return type does not match declaration");
errorframe_append(&frame, &info);
errorframe_report(&frame, opt->check.errors);
return AST_ERROR;
}
// Check partiality
if((ast_id(decl_error) == TK_NONE) && (ast_id(call_error) != TK_NONE))
{
ast_error(opt->check.errors, call_error,
"call is partial but the declaration is not");
return AST_ERROR;
}
if((ast_id(decl_error) == TK_QUESTION) ||
(ast_id(call_error) == TK_QUESTION))
{
ast_seterror(call);
}
// Store the declaration so that codegen can generate a non-variadic
// signature for the FFI call.
ast_setdata(call, decl);
ast_settype(call, decl_ret_type);
ast_inheritflags(call);
return AST_OK;
}
bool expr_return(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
if(t->frame->method_body == NULL)
{
ast_error(ast, "return must occur in a method body");
return false;
}
// return is always the last expression in a sequence
assert(ast_sibling(ast) == NULL);
if(ast_parent(ast) == t->frame->method_body)
{
ast_error(ast,
"use return only to exit early from a method, not at the end");
return false;
}
ast_t* type = ast_childidx(t->frame->method, 4);
ast_t* body = ast_child(ast);
if(!coerce_literals(&body, type, opt))
return false;
ast_t* body_type = ast_type(body);
if(is_typecheck_error(body_type))
return false;
if(is_control_type(body_type))
{
ast_error(body, "return value cannot be a control statement");
return false;
}
bool ok = true;
switch(ast_id(t->frame->method))
{
case TK_NEW:
if(!is_none(body_type))
{
ast_error(ast, "return in a constructor must return None");
ok = false;
}
break;
case TK_BE:
if(!is_none(body_type))
{
ast_error(ast, "return in a behaviour must return None");
ok = false;
}
break;
default:
{
// The body type must be a subtype of the return type, and an alias of
// the body type must be a subtype of an alias of the return type.
ast_t* a_type = alias(type);
ast_t* a_body_type = alias(body_type);
if(!is_subtype(body_type, type) || !is_subtype(a_body_type, a_type))
{
ast_t* last = ast_childlast(body);
ast_error(last, "returned value isn't the return type");
ast_error(type, "function return type: %s", ast_print_type(type));
ast_error(body_type, "returned value type: %s",
ast_print_type(body_type));
ok = false;
}
ast_free_unattached(a_type);
ast_free_unattached(a_body_type);
}
}
ast_settype(ast, ast_from(ast, TK_RETURN));
ast_inheritflags(ast);
return ok;
}
bool expr_seq(pass_opt_t* opt, ast_t* ast)
{
bool ok = true;
// Any expression other than the last that is still literal is an error
for(ast_t* p = ast_child(ast); ast_sibling(p) != NULL; p = ast_sibling(p))
{
ast_t* p_type = ast_type(p);
if(is_typecheck_error(p_type))
{
ok = false;
} else if(is_type_literal(p_type)) {
ast_error(p, "Cannot infer type of unused literal");
ok = false;
}
}
// We might already have a type due to a return expression.
ast_t* type = ast_type(ast);
ast_t* last = ast_childlast(ast);
if((type != NULL) && !coerce_literals(&last, type, opt))
return false;
// Type is unioned with the type of the last child.
type = control_type_add_branch(type, last);
ast_settype(ast, type);
ast_inheritflags(ast);
if(!ast_has_scope(ast))
return ok;
ast_t* parent = ast_parent(ast);
switch(ast_id(parent))
{
case TK_TRY:
case TK_TRY_NO_CHECK:
{
// Propagate consumes forward in a try expression.
AST_GET_CHILDREN(parent, body, else_clause, then_clause);
if(body == ast)
{
// Push our consumes, but not defines, to the else clause.
ast_inheritbranch(else_clause, body);
ast_consolidate_branches(else_clause, 2);
} else if(else_clause == ast) {
// Push our consumes, but not defines, to the then clause. This
// includes the consumes from the body.
ast_inheritbranch(then_clause, else_clause);
ast_consolidate_branches(then_clause, 2);
}
}
default:
{}
}
return ok;
}
bool expr_assign(pass_opt_t* opt, ast_t* ast)
{
// Left and right are swapped in the AST to make sure we type check the
// right side before the left. Fetch them in the opposite order.
assert(ast != NULL);
AST_GET_CHILDREN(ast, right, left);
ast_t* l_type = ast_type(left);
if(!is_lvalue(&opt->check, left, is_result_needed(ast)))
{
ast_error(ast, "left side must be something that can be assigned to");
return false;
}
assert(l_type != NULL);
if(!coerce_literals(&right, l_type, opt))
return false;
ast_t* r_type = ast_type(right);
if(is_typecheck_error(r_type))
return false;
if(!infer_locals(left, r_type))
return false;
// Inferring locals may have changed the left type.
l_type = ast_type(left);
// Assignment is based on the alias of the right hand side.
ast_t* a_type = alias(r_type);
if(!is_subtype(a_type, l_type))
{
ast_error(ast, "right side must be a subtype of left side");
ast_error(a_type, "right side type: %s", ast_print_type(a_type));
ast_error(l_type, "left side type: %s", ast_print_type(l_type));
ast_free_unattached(a_type);
return false;
}
if((ast_id(left) == TK_TUPLE) && (ast_id(a_type) != TK_TUPLETYPE))
{
switch(ast_id(a_type))
{
case TK_UNIONTYPE:
ast_error(ast,
"can't destructure a union using assignment, use pattern matching "
"instead");
break;
case TK_ISECTTYPE:
ast_error(ast,
"can't destructure an intersection using assignment, use pattern "
"matching instead");
break;
default:
assert(0);
break;
}
ast_error(a_type, "right side type: %s", ast_print_type(a_type));
ast_free_unattached(a_type);
return false;
}
bool ok_safe = safe_to_write(left, a_type);
if(!ok_safe)
{
if(ast_id(left) == TK_FVARREF && ast_child(left) != NULL &&
ast_id(ast_child(left)) == TK_THIS)
{
// We are writing to a field in this
ast_t* fn = ast_nearest(left, TK_FUN);
if(fn != NULL)
{
ast_t* iso = ast_child(fn);
assert(iso != NULL);
token_id iso_id = ast_id(iso);
if(iso_id == TK_BOX || iso_id == TK_VAL || iso_id == TK_TAG)
{
ast_error(ast, "cannot write to a field in a %s function",
lexer_print(iso_id));
ast_free_unattached(a_type);
return false;
}
}
}
ast_error(ast, "not safe to write right side to left side");
ast_error(a_type, "right side type: %s", ast_print_type(a_type));
ast_free_unattached(a_type);
return false;
}
ast_free_unattached(a_type);
// If it's an embedded field, check for a constructor result.
if(ast_id(left) == TK_EMBEDREF)
{
if((ast_id(right) != TK_CALL) ||
(ast_id(ast_childidx(right, 2)) != TK_NEWREF))
{
ast_error(ast, "an embedded field must be assigned using a constructor");
return false;
}
}
ast_settype(ast, consume_type(l_type, TK_NONE));
ast_inheritflags(ast);
return true;
}
static bool check_arg_types(pass_opt_t* opt, ast_t* params, ast_t* positional,
bool partial)
{
// Check positional args vs params.
ast_t* param = ast_child(params);
ast_t* arg = ast_child(positional);
while(arg != NULL)
{
if(ast_id(arg) == TK_NONE)
{
if(partial)
{
// Don't check missing arguments for partial application.
arg = ast_sibling(arg);
param = ast_sibling(param);
continue;
} else {
// Pick up a default argument if we can.
if(!apply_default_arg(opt, param, arg))
return false;
}
}
ast_t* p_type = ast_childidx(param, 1);
if(!coerce_literals(&arg, p_type, opt))
return false;
ast_t* arg_type = ast_type(arg);
if(is_typecheck_error(arg_type))
return false;
if(ast_checkflag(arg, AST_FLAG_JUMPS_AWAY))
{
ast_error(opt->check.errors, arg,
"can't use a control expression in an argument");
return false;
}
ast_t* a_type = alias(arg_type);
errorframe_t info = NULL;
if(!is_subtype(a_type, p_type, &info, opt))
{
errorframe_t frame = NULL;
ast_error_frame(&frame, arg, "argument not a subtype of parameter");
errorframe_append(&frame, &info);
if(ast_checkflag(ast_type(arg), AST_FLAG_INCOMPLETE))
ast_error_frame(&frame, arg,
"this might be possible if all fields were already defined");
errorframe_report(&frame, opt->check.errors);
ast_free_unattached(a_type);
return false;
}
ast_free_unattached(a_type);
arg = ast_sibling(arg);
param = ast_sibling(param);
}
return true;
}