Add pythagorean query

python/ql/src/Numerics/Pythagorean.ql

@@ -0,0 +1,48 @@
+/**
+ * @name Pythagorean calculation with sub-optimal numerics
+ * @description Calculating the length of the hypotenuse using the standard formula may lead to overflow.
+ * @kind problem
+ * @tags accuracy
+ * @problem.severity warning
+ * @sub-severity low
+ * @precision medium
+ * @id py/pythagorean
+ */
+
+import python
+
+predicate squareOp(BinaryExpr e) {
+  e.getOp() instanceof Pow and e.getRight().(IntegerLiteral).getN() = "2"
+}
+
+predicate squareMul(BinaryExpr e) {
+  e.getOp() instanceof Mult and e.getRight().(Name).getId() = e.getLeft().(Name).getId()
+}
+
+predicate squareRef(Name e) {
+  e.isUse() and
+  exists(SsaVariable v, Expr s |
+    v.getVariable() = e.getVariable() |
+    s = v.getDefinition().getNode().getParentNode().(AssignStmt).getValue() and
+    square(s)
+  )
+}
+
+predicate square(Expr e) {
+  squareOp(e)
+  or
+  squareMul(e)
+  or
+  squareRef(e)
+}
+
+from
+  Call c,
+  BinaryExpr s
+where
+  c.getFunc().toString() = "sqrt" and
+  c.getArg(0) = s and
+  s.getOp() instanceof Add and
+  square(s.getLeft()) and square(s.getRight())
+select
+  c, "Pythagorean calculation with sub-optimal numerics"