Add simplifiable-call-with-array-arg-and-indices.ql

codeql-custom-queries-java/queries/recommendations/simplifiable-call-with-array-arg-and-indices.ql

@@ -0,0 +1,67 @@
+/**
+ * Finds calls with an array as argument which can possibly be simplified
+ * by omitting indices or the array length argument because there is
+ * a method overload which accepts only the array for convenience.
+ *
+ * For example:
+ * ```java
+ * out.write(array, 0, array.length)
+ * // can be simplified:
+ * out.write(array)
+ * ```
+ *
+ * **Important:** Please verify that the alternative suggested by this
+ * query behaves the same way. This query does not check the implementation
+ * of the proposed alternative but only determines it based on its signature.
+ *
+ * @kind problem
+ */
+
+import java
+
+class ArrayLengthAccess extends FieldRead {
+  ArrayLengthAccess() { getField() instanceof ArrayLengthField }
+}
+
+from Variable array, Call call, Callable callee, Callable alternative
+where
+  call.getCallee() = callee and
+  // Either `method(array, array.length)` or `method(array, 0, array.length)`
+  (
+    call.getNumArgument() = 2 and
+    call.getArgument(0) = array.getAnAccess() and
+    call.getArgument(1).(ArrayLengthAccess).getQualifier() = array.getAnAccess()
+    or
+    call.getNumArgument() = 3 and
+    call.getArgument(0) = array.getAnAccess() and
+    call.getArgument(1).(IntegerLiteral).getIntValue() = 0 and
+    call.getArgument(2).(ArrayLengthAccess).getQualifier() = array.getAnAccess()
+  ) and
+  // Altnerative is available on same receiver
+  (
+    alternative.getDeclaringType() = callee.getDeclaringType().getASourceSupertype*() or
+    alternative.getDeclaringType() = call.(MethodAccess).getReceiverType().getASourceSupertype*()
+  ) and
+  // Alternative has same name and return type, and a single parameter of the same array type
+  alternative.getName() = callee.getName() and
+  alternative.getReturnType() = callee.getReturnType() and
+  alternative.getNumberOfParameters() = 1 and
+  alternative.getParameterType(0) = callee.getParameterType(0) and
+  // And is same static or non-static as called callable
+  (
+    callee.isStatic() and alternative.isStatic()
+    or
+    not callee.isStatic() and not alternative.isStatic()
+  ) and
+  // And is at least as visible as called callable
+  (
+    alternative.isPublic()
+    or
+    callee.isProtected() and alternative.isProtected()
+  ) and
+  // Don't suggest infinite recursion by calling itself
+  not (
+    call.getEnclosingCallable() = alternative or
+    call.getEnclosingCallable().(Method).getASourceOverriddenMethod*() = alternative
+  )
+select call, "Could possibly instead call `" + alternative.getStringSignature() + "`"