static int check_body_send(ast_t* ast, bool in_final)
{
if(ast_checkflag(ast, AST_FLAG_RECURSE_1))
return FINAL_RECURSE;
if(ast_cansend(ast))
return FINAL_CAN_SEND;
if(!ast_mightsend(ast))
return FINAL_NO_SEND;
ast_setflag(ast, AST_FLAG_RECURSE_1);
int r = check_expr_send(ast, in_final);
if(r == FINAL_NO_SEND)
{
// Mark the body as no send.
ast_clearmightsend(ast);
} else if((r & FINAL_CAN_SEND) != 0) {
// Mark the body as can send.
ast_setsend(ast);
}
ast_clearflag(ast, AST_FLAG_RECURSE_1);
return r;
}
static void show_send(pass_opt_t* opt, ast_t* ast)
{
ast_t* child = ast_child(ast);
while(child != NULL)
{
if(ast_cansend(child) || ast_mightsend(child))
show_send(opt, child);
child = ast_sibling(child);
}
if(ast_id(ast) == TK_CALL)
{
if(ast_cansend(ast))
ast_error(opt->check.errors, ast, "a message can be sent here");
else if(ast_mightsend(ast))
ast_error(opt->check.errors, ast, "a message might be sent here");
}
}
static int check_expr_send(ast_t* ast, bool in_final)
{
int send = FINAL_NO_SEND;
if(ast_id(ast) == TK_CALL)
send |= check_call_send(ast, in_final);
ast_t* child = ast_child(ast);
while(child != NULL)
{
if(ast_mightsend(child))
send |= check_expr_send(child, in_final);
child = ast_sibling(child);
}
return send;
}
bool expr_try(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, body, else_clause, then_clause);
// It has to be possible for the left side to result in an error.
if((ast_id(ast) == TK_TRY) && !ast_canerror(body))
{
ast_error(body, "try expression never results in an error");
return false;
}
ast_t* body_type = ast_type(body);
ast_t* else_type = ast_type(else_clause);
ast_t* then_type = ast_type(then_clause);
if(is_typecheck_error(body_type) ||
is_typecheck_error(else_type) ||
is_typecheck_error(then_type))
return false;
ast_t* type = NULL;
if(!is_control_type(body_type))
type = control_type_add_branch(type, body);
if(!is_control_type(else_type))
type = control_type_add_branch(type, else_clause);
if(type == NULL)
{
if(ast_sibling(ast) != NULL)
{
ast_error(ast_sibling(ast), "unreachable code");
return false;
}
type = ast_from(ast, TK_TRY);
}
// The then clause does not affect the type of the expression.
if(is_control_type(then_type))
{
ast_error(then_clause, "then clause always terminates the function");
return false;
}
if(is_type_literal(then_type))
{
ast_error(then_clause, "Cannot infer type of unused literal");
return false;
}
ast_settype(ast, type);
// Doesn't inherit error from the body.
if(ast_canerror(else_clause) || ast_canerror(then_clause))
ast_seterror(ast);
if(ast_cansend(body) || ast_cansend(else_clause) || ast_cansend(then_clause))
ast_setsend(ast);
if(ast_mightsend(body) || ast_mightsend(else_clause) ||
ast_mightsend(then_clause))
ast_setmightsend(ast);
literal_unify_control(ast, opt);
// Push the symbol status from the then clause to our parent scope.
ast_inheritstatus(ast_parent(ast), then_clause);
return true;
}