False Negative: ConstantLoopCondition.ql misses loops whose exit condition stays constant after being wrapped in helpers.

Version
codeql 2.24.3

## Checker
- Checker id: `Likely Bugs/Termination/ConstantLoopCondition.ql`
- Checker description: This checker detects loop conditions that are constant within the loop body, potentially leading to non-terminating loops.

## Description of the false negative
These loops are still non-terminating for the same reason as the direct patterns: the value that controls exit never changes inside the loop. The code only wraps that check in a helper or rewrites the exit test into an equivalent form.

That should not move the sample outside the scope of `Likely Bugs/Termination/ConstantLoopCondition.ql`.

## Affected test cases
### `PosCase1_Var5.java`
`x` is never updated, so `check(x)` never changes. The helper only obscures an otherwise obvious infinite loop.

```java
// while loop with condition variable defined outside and no updates in body should be flagged as infinite loop
package scensct.var.pos;

public class PosCase1_Var5 {
private static boolean check(int val) {
return val > 0;
}

public static void main(String[] args) {
int x = 5;
// condition via helper method, x not updated
while (check(x)) {
System.out.println("stuck via method");
}
}
}
```

### `PosCase2_Var4.java`
`conditionHolds(y)` is stable because `y` is never modified in the loop body. This is still a constant loop condition.

```java
// while loop with condition using final field and variable defined outside should be flagged as infinite loop
package scensct.var.pos;

public class PosCase2_Var4 {
private static final int LIMIT = 10;
public static void main(String[] args) {
int y = 3;
// Extract condition evaluation to a helper method
while (conditionHolds(y)) {
System.out.println("stuck");
}
}
private static boolean conditionHolds(int val) {
return val < LIMIT;
}
}
```

### `PosCase5_Var5.java`
The loop exit is written as a guarded `return`, but `counter` never changes, so `shouldExit(counter)` remains false forever and the loop still does not terminate.

```java
// while true loop with if condition using variable defined outside controlling all exits should be flagged as infinite loop
package scensct.var.pos;

public class PosCase5_Var5 {
// Helper method to compute constant condition
private static boolean shouldExit(int c) {
return c == 1;
}

public static void main(String[] args) {
int counter = 0;
while (true) {
// Exit condition hidden in method call
if (shouldExit(counter)) {
return;
}
System.out.println("stuck");
}
}
}
```

## Cause analysis
The misses point to a query that is matching specific loop syntax rather than the underlying stability of the condition. Once the condition is computed in a helper or turned into an equivalent exit guard, the analysis seems to stop following it.

That leaves a real blind spot. Developers often factor loop predicates into helpers, and those helpers do not make a non-terminating loop any safer.

## References
None known.

Start with Likely Bugs/Termination/ConstantLoopCondition.ql and inspect how its existing tests cover constant loop conditions. Reproduce the misses in PosCase1_Var5.java, PosCase2_Var4.java, and PosCase5_Var5.java, then run the relevant query tests. Done means all three helper-wrapped or guarded non-terminating loops are detected without losing existing coverage.

Scritto dal modello di indicizzazione a partire dal testo della issue.