/**

* @name Returning tuples with varying lengths

* @description A function that potentially returns tuples of different lengths may indicate a problem.

* @kind problem

* @tags reliability

* maintainability

* quality

* @problem.severity recommendation

* @sub-severity high

* @precision high

* @id py/mixed-tuple-returns

*/

import python

import semmle.python.ApiGraphs

predicate returns_tuple_of_size(Function func, int size, Tuple tuple) {

}

from Function func, int s1, int s2, AstNode t1, AstNode t2

where

returns_tuple_of_size(func, s1, t1) and

returns_tuple_of_size(func, s2, t2) and

s1 < s2 and

// Don't report on functions that have a return type annotation

not exists(func.getDefinition().(FunctionExpr).getReturns())

select func, func.getQualifiedName() + " returns $@ and $@.", t1, "tuple of size " + s1, t2,

"tuple of size " + s2