False Negative: ConstantExpAppearsNonConstant.ql misses expressions that stay constant after trivial local rewrites.

Likely Bugs/Arithmetic/ConstantExpAppearsNonConstant.ql から始め、ローカル変数と書き換えられた式を通じて定数の結果をどのように伝播させているかを調べてください。影響を受ける例として PosCase1.java、PosCase3_Var1.java、PosCase3_Var2.java を確認してください。クエリが説明されている定数式を認識し、既存の検出動作を失わなければ完了です。

Version
codeql 2.24.3

Checker

• Checker id: Likely Bugs/Arithmetic/ConstantExpAppearsNonConstant.ql
• Checker description: This checker detects expressions that always evaluate to the same constant value but are not recognized as compile-time constants by the compiler, often due to containing non-constant sub-expressions that don't affect the final result.

Description of the false negative

These cases still reduce to a constant result at runtime. One multiplies by zero. The others use true || condition, which is still always true regardless of the non-constant boolean input.

The only change is that the constant-looking behavior is expressed through locals or a slightly different spelling.

Affected test cases

PosCase1.java

nonConstant * 0 still evaluates to zero regardless of the non-constant operand.

PosCase3_Var1.java and PosCase3_Var2.java

Both variants are still logical constants. Boolean.TRUE || condition and alwaysTrue || condition should both be recognized as always true.

Cause analysis

This looks like a propagation gap. Likely Bugs/Arithmetic/ConstantExpAppearsNonConstant.ql appears to lose the constant result once the expression is one step less direct, even though the same algebraic reasoning still applies.

That makes the query miss a kind of bug it should be well suited to catch.

Reproduction code

PosCase1.java

// Multiplication by zero with integer literal zero operand should be flagged as always evaluating to zero.
package scensct.core.pos;

public class PosCase1 {
    public PosCase1() {
        int nonConstant = getNonConstant(); // Non-constant subexpression
        int result = nonConstant * 0; // Multiplication by zero, always zero
        // Use result in a conditional to emphasize constant evaluation
        if (result == 0) {
            // This branch is always taken
            System.out.println("Always zero");
        }
    }

    private int getNonConstant() {
        return (int) (Math.random() * 100); // Non-constant value
    }
}

References

None known.