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/**

* @name Nested loops with same variable

* @description Nested loops in which the target variable is the same for each loop make

* the behavior of the loops difficult to understand.

* @kind problem

* @tags quality

* maintainability

* readability

* @problem.severity recommendation

* @sub-severity high

* @precision very-high

* @id py/nested-loops-with-same-variable

import python

predicate loop_variable(For f, Variable v) { f.getTarget().defines(v) }

predicate variableUsedInNestedLoops(For inner, For outer, Variable v) {

/* Only treat loops in body as inner loops. Loops in the else clause are ignored. */

outer.getBody().contains(inner) and

loop_variable(inner, v) and

loop_variable(outer, v) and

/* Ignore cases where there is no use of the variable or the only use is in the inner loop */

exists(Name n | n.uses(v) and outer.contains(n) and not inner.contains(n))

}

from For inner, For outer, Variable v

where variableUsedInNestedLoops(inner, outer, v)

select inner, "Nested for statement uses loop variable '" + v.getId() + "' of enclosing $@.", outer,

"for statement"