Refactor to share a predicate between M0-1-3 and M0-1-9 reducing duplication.

Author: fjatWbyT

cpp/autosar/src/rules/M0-1-3/UnusedLocalVariable.ql

@@ -44,11 +44,7 @@ int getUseCountConservatively(Variable v) {
       count(StaticAssert s | s.getCondition().getAChild*().getValue() = getConstExprValue(v)) +
       // In case an array type uses a constant in the same scope as the constexpr variable,
       // consider it as used.
-      count(ArrayType at, LocalVariable arrayVariable |
-        arrayVariable.getType().resolveTypedefs() = at and
-        v.(PotentiallyUnusedLocalVariable).getFunction() = arrayVariable.getFunction() and
-        at.getArraySize().toString() = getConstExprValue(v)
-      )
+      countUsesInLocalArraySize(v)
 }
 
 from PotentiallyUnusedLocalVariable v

cpp/common/src/codingstandards/cpp/deadcode/UnusedVariables.qll

@@ -150,3 +150,19 @@ predicate maybeACompileTimeTemplateArgument(Variable v) {
     )
   )
 }
+
+/** Gets the constant value of a constexpr/const variable. */
+private string getConstExprValue(Variable v) {
+  result = v.getInitializer().getExpr().getValue() and
+  (v.isConst() or v.isConstexpr())
+}
+
+/**
+ * Counts uses of `Variable` v in a local array of size `n`
+ */
+int countUsesInLocalArraySize(Variable v) {
+  result = count(ArrayType at, LocalVariable arrayVariable |
+		 arrayVariable.getType().resolveTypedefs() = at and
+		 v.(PotentiallyUnusedLocalVariable).getFunction() = arrayVariable.getFunction() and
+		 at.getArraySize().toString() = getConstExprValue(v))
+}

cpp/common/src/codingstandards/cpp/rules/deadcode/DeadCode.qll

@@ -22,25 +22,6 @@ abstract class DeadCodeSharedQuery extends Query { }
 
 Query getQuery() { result instanceof DeadCodeSharedQuery }
 
-/**
- * Returns integer value of a constexpr variable
- */
-int getConstexprValue(Variable v) {
-  result = v.getInitializer().getExpr().getValue().toInt() and v.isConstexpr()
-}
-
-/**
- * Holds if `Variable` v is used for a local array size with value `n`
- */
-bindingset[n]
-predicate isUsedInLocalArraySize(Variable v, int n) {
-  // Cf. https://github.com/github/codeql-coding-standards/pull/660/files.
-  count(ArrayType at, LocalVariable arrayVariable |
-        arrayVariable.getType().resolveTypedefs() = at and
-        v.(PotentiallyUnusedLocalVariable).getFunction() = arrayVariable.getFunction() and
-        at.getArraySize() = n) > 0
-}
-
 /**
  * Holds if the `Stmt` `s` is either dead or unreachable.
  */
@@ -72,7 +53,7 @@ predicate isDeadStmt(Stmt s) {
           va.getTarget() = v and
           not isDeadOrUnreachableStmt(va.getEnclosingStmt())
         ) and
-        not isUsedInLocalArraySize(v, getConstexprValue(v))
+        not (countUsesInLocalArraySize(v) > 0)
       )
     )
   )