import cpp

from Function f, Parameter err, ReturnStmt r
where
// Check that f has a bson_error_t * output parameter.
err.getType().getName() = "bson_error_t *" and
err.getFunction() = f and
// And that f returns a boolean
f.getType().getName() = "bool" and
// And there is a return false;
r.getExpr().(Literal).getValue().toInt() = 0 and
r.getEnclosingFunction() = f and
// no a call to bson_set_error in the same block.
not exists (FunctionCall fc |
    fc.getTarget().getQualifiedName() = "bson_set_error" and
    r.getEnclosingBlock() = fc.getEnclosingBlock()
) and
// no a call to a function taking a bson_error_t in the same block.
not exists (FunctionCall fc, Parameter arg |
    arg.getName() = err.getName() and
    arg.getFunction() = fc.getTarget() and
    r.getEnclosingBlock() = fc.getEnclosingBlock()
)
and
// no call to a function in an if condition containing
not exists (FunctionCall fc, Parameter arg, IfStmt ifstmt |
    arg.getName() = err.getName() and
    arg.getFunction() = fc.getTarget() and
    fc.getParent*() = ifstmt.getCondition() and
    r.getParent*() = ifstmt.getThen()
)
// Not a call to bson_set_error in the if condition of the nested block
select r, f