Changed based on review comments.

Author: rak3-sh

change_notes/2023-06-28-unused-local-function-use-cases.md

@@ -1 +1,6 @@
- - `A0-1-3` - Considered use cases mentioned on issue [121](https://github.com/github/codeql-coding-standards/issues/121) while reporting a local function as "unused".
+- `A0-1-3` - Considered the following additional use cases while reporting a local function as "unused".
+  - The address of a function is taken
+  - The operand of an expression in an unevaluated context
+  - Functions marked with [[maybe_unused]]
+  - Explicitly deleted functions e.g. =delete
+  - Use of any overload of a function in an overload set constitute a use of all members of the set. An overload set is a set of functions with the same name that differ in the number, type and/or qualifiers of their parameters.

cpp/autosar/src/rules/A0-1-3/UnusedLocalFunction.ql

@@ -19,29 +19,14 @@ import codingstandards.cpp.autosar
 import codingstandards.cpp.DynamicCallGraph
 import codingstandards.cpp.deadcode.UnusedFunctions
 
-/** Checks if a function call exists to the function
- * passed in the arguments.
- */
-predicate isCalled(Function unusedFunction) {
-  unusedFunction = getTarget(_)
-}
 
 /** Checks if an overloaded function of
  * the function passed in the arguments, is called.
  */
 predicate overloadedFunctionIsCalled(Function unusedFunction) {
-  exists (Function f | f = unusedFunction.getAnOverload() and isCalled(f))
-  or
-  unusedFunction.getNamespace().isAnonymous() and
-    exists (TopLevelFunction overloadedFunction |
-      overloadedFunction != unusedFunction and
-      ((overloadedFunction.getName() = unusedFunction.getName()) or
-        (overloadedFunction.getQualifiedName() =
-          unusedFunction.getQualifiedName()))
-      )
+  exists (Function f | f = unusedFunction.getAnOverload() and f = getTarget(_))
 }
 
-
 /** Checks if a Function's address was taken. */
 predicate addressBeenTaken(Function unusedFunction)
 {

cpp/autosar/test/rules/A0-1-3/test.cpp

@@ -121,13 +121,6 @@ static int overload1(int c, int d) // COMPLAINT - overload1(int) is called.
   return c + d;
 }
 
-namespace {
-int overload1(int c, float d) // COMPLAINT - overload1(int) is called.
-{
-  return c + d;
-}
-} // namespace
-
 int overload = overload1(5);
 
 class classWithOverloads {

rule_packages/cpp/DeadCode.json

@@ -67,7 +67,10 @@
           "tags": [
             "readability",
             "maintainability"
-          ]
+          ],
+          "implementation_scope": {
+            "description": "Functions defined in anonymous (unnamed) namespaces and global namespaces are not considered to be part of the same overload set."
+          }
         }
       ],
       "title": "Every function defined in an anonymous namespace, or static function with internal linkage, or private member function shall be used."