Implement Rule 0.2.4, unused functions with limited visibility.

change_notes/2026-02-18-unused-member-functions-with-internal-linkage.md

@@ -0,0 +1,2 @@
+ - `A0-1-3` - `UnusedLocalFunction.ql`:
+   - Query now reports unused public members of classes in anonymous namespaces, which have internal linkage.

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

@@ -16,95 +16,10 @@
 
 import cpp
 import codingstandards.cpp.autosar
-import codingstandards.cpp.DynamicCallGraph
-import codingstandards.cpp.deadcode.UnusedFunctions
+import codingstandards.cpp.rules.unusedlocalfunction.UnusedLocalFunction
 
-/**
- * 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 f = getTarget(_))
-}
-
-/** Checks if a Function's address was taken. */
-predicate addressBeenTaken(Function unusedFunction) {
-  exists(FunctionAccess fa | fa.getTarget() = unusedFunction)
-}
-
-/** A `Function` nested in an anonymous namespace. */
-class AnonymousNamespaceFunction extends Function {
-  AnonymousNamespaceFunction() { getNamespace().getParentNamespace*().isAnonymous() }
-}
-
-/**
- * A function which is "local" to a particular scope or translation unit.
- */
-class LocalFunction extends UnusedFunctions::UsableFunction {
-  string localFunctionType;
-
-  LocalFunction() {
-    this.(MemberFunction).isPrivate() and
-    localFunctionType = "Private member"
-    or
-    // A function in an anonymous namespace (which is deduced to have internal linkage)
-    this instanceof AnonymousNamespaceFunction and
-    // Not member functions, which don't have internal linkage
-    not this instanceof MemberFunction and
-    localFunctionType = "Anonymous namespace"
-    or
-    // Static functions with internal linkage
-    this.isStatic() and
-    // Member functions never have internal linkage
-    not this instanceof MemberFunction and
-    // Functions in anonymous namespaces automatically have the "static" specifier added by the
-    // extractor. We therefore excluded them from this case, and instead report them in the
-    // anonymous namespace, as we don't know whether the "static" specifier was explicitly
-    // provided by the user.
-    not this instanceof AnonymousNamespaceFunction and
-    localFunctionType = "Static"
-  }
-
-  /** Gets the type of local function. */
-  string getLocalFunctionType() { result = localFunctionType }
+module UnusedLocalFunctionConfig implements UnusedLocalFunctionConfigSig {
+  Query getQuery() { result = DeadCodePackage::unusedLocalFunctionQuery() }
 }
 
-from LocalFunction unusedLocalFunction, string name
-where
-  not isExcluded(unusedLocalFunction, DeadCodePackage::unusedLocalFunctionQuery()) and
-  // No static or dynamic call target for this function
-  not unusedLocalFunction = getTarget(_) and
-  // If this is a TemplateFunction or an instantiation of a template, then only report it as unused
-  // if all other instantiations of the template are unused
-  not exists(
-    Function functionFromUninstantiatedTemplate, Function functionFromInstantiatedTemplate
-  |
-    // `unusedLocalFunction` is a template instantiation from `functionFromUninstantiatedTemplate`
-    unusedLocalFunction.isConstructedFrom(functionFromUninstantiatedTemplate)
-    or
-    // `unusedLocalFunction` is from an uninstantiated template
-    unusedLocalFunction = functionFromUninstantiatedTemplate
-  |
-    // There exists an instantiation which is called
-    functionFromInstantiatedTemplate.isConstructedFrom(functionFromUninstantiatedTemplate) and
-    functionFromInstantiatedTemplate = getTarget(_)
-  ) and
-  // A function is defined as "used" if any one of the following holds true:
-  // - It's an explicitly deleted functions e.g. =delete
-  // - It's annotated as "[[maybe_unused]]"
-  // - It's part of an overloaded set and any one of the overloaded instance
-  //   is called.
-  // - It's an operand of an expression in an unevaluated context.
-  not unusedLocalFunction.isDeleted() and
-  not unusedLocalFunction.getAnAttribute().getName() = "maybe_unused" and
-  not overloadedFunctionIsCalled(unusedLocalFunction) and
-  not addressBeenTaken(unusedLocalFunction) and
-  // Get a printable name
-  (
-    if exists(unusedLocalFunction.getQualifiedName())
-    then name = unusedLocalFunction.getQualifiedName()
-    else name = unusedLocalFunction.getName()
-  )
-select unusedLocalFunction,
-  unusedLocalFunction.getLocalFunctionType() + " function " + name +
-    " is not statically called, or is in an unused template."
+import UnusedLocalFunction<UnusedLocalFunctionConfig>

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

@@ -0,0 +1,110 @@
+/**
+ * @id cpp/autosar/unused-local-function
+ * @name A0-1-3: Unused local function
+ * @description Every function defined in an anonymous namespace, or static function with internal
+ *              linkage, or private member function shall be used.
+ * @kind problem
+ * @precision very-high
+ * @problem.severity warning
+ * @tags external/autosar/id/a0-1-3
+ *       readability
+ *       maintainability
+ *       external/autosar/allocated-target/implementation
+ *       external/autosar/enforcement/automated
+ *       external/autosar/obligation/required
+ */
+
+import cpp
+import codingstandards.cpp.autosar
+import codingstandards.cpp.DynamicCallGraph
+import codingstandards.cpp.deadcode.UnusedFunctions
+
+/**
+ * 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 f = getTarget(_))
+}
+
+/** Checks if a Function's address was taken. */
+predicate addressBeenTaken(Function unusedFunction) {
+  exists(FunctionAccess fa | fa.getTarget() = unusedFunction)
+}
+
+/** A `Function` nested in an anonymous namespace. */
+class AnonymousNamespaceFunction extends Function {
+  AnonymousNamespaceFunction() { getNamespace().getParentNamespace*().isAnonymous() }
+}
+
+/**
+ * A function which is "local" to a particular scope or translation unit.
+ */
+class LocalFunction extends UnusedFunctions::UsableFunction {
+  string localFunctionType;
+
+  LocalFunction() {
+    this.(MemberFunction).isPrivate() and
+    localFunctionType = "Private member"
+    or
+    // A function in an anonymous namespace (which is deduced to have internal linkage)
+    this instanceof AnonymousNamespaceFunction and
+    // Not member functions, which don't have internal linkage
+    not this instanceof MemberFunction and
+    localFunctionType = "Anonymous namespace"
+    or
+    // Static functions with internal linkage
+    this.isStatic() and
+    // Member functions never have internal linkage
+    not this instanceof MemberFunction and
+    // Functions in anonymous namespaces automatically have the "static" specifier added by the
+    // extractor. We therefore excluded them from this case, and instead report them in the
+    // anonymous namespace, as we don't know whether the "static" specifier was explicitly
+    // provided by the user.
+    not this instanceof AnonymousNamespaceFunction and
+    localFunctionType = "Static"
+  }
+
+  /** Gets the type of local function. */
+  string getLocalFunctionType() { result = localFunctionType }
+}
+
+from LocalFunction unusedLocalFunction, string name
+where
+  not isExcluded(unusedLocalFunction, DeadCodePackage::unusedLocalFunctionQuery()) and
+  // No static or dynamic call target for this function
+  not unusedLocalFunction = getTarget(_) and
+  // If this is a TemplateFunction or an instantiation of a template, then only report it as unused
+  // if all other instantiations of the template are unused
+  not exists(
+    Function functionFromUninstantiatedTemplate, Function functionFromInstantiatedTemplate
+  |
+    // `unusedLocalFunction` is a template instantiation from `functionFromUninstantiatedTemplate`
+    unusedLocalFunction.isConstructedFrom(functionFromUninstantiatedTemplate)
+    or
+    // `unusedLocalFunction` is from an uninstantiated template
+    unusedLocalFunction = functionFromUninstantiatedTemplate
+  |
+    // There exists an instantiation which is called
+    functionFromInstantiatedTemplate.isConstructedFrom(functionFromUninstantiatedTemplate) and
+    functionFromInstantiatedTemplate = getTarget(_)
+  ) and
+  // A function is defined as "used" if any one of the following holds true:
+  // - It's an explicitly deleted functions e.g. =delete
+  // - It's annotated as "[[maybe_unused]]"
+  // - It's part of an overloaded set and any one of the overloaded instance
+  //   is called.
+  // - It's an operand of an expression in an unevaluated context.
+  not unusedLocalFunction.isDeleted() and
+  not unusedLocalFunction.getAnAttribute().getName() = "maybe_unused" and
+  not overloadedFunctionIsCalled(unusedLocalFunction) and
+  not addressBeenTaken(unusedLocalFunction) and
+  // Get a printable name
+  (
+    if exists(unusedLocalFunction.getQualifiedName())
+    then name = unusedLocalFunction.getQualifiedName()
+    else name = unusedLocalFunction.getName()
+  )
+select unusedLocalFunction,
+  unusedLocalFunction.getLocalFunctionType() + " function " + name +
+    " is not statically called, or is in an unused template."

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

@@ -0,0 +1 @@
+cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.ql

cpp/common/src/codingstandards/cpp/exclusions/cpp/DeadCode10.qll

@@ -0,0 +1,26 @@
+//** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY.  **/
+import cpp
+import RuleMetadata
+import codingstandards.cpp.exclusions.RuleMetadata
+
+newtype DeadCode10Query = TUnusedLimitedVisibilityFunctionQuery()
+
+predicate isDeadCode10QueryMetadata(Query query, string queryId, string ruleId, string category) {
+  query =
+    // `Query` instance for the `unusedLimitedVisibilityFunction` query
+    DeadCode10Package::unusedLimitedVisibilityFunctionQuery() and
+  queryId =
+    // `@id` for the `unusedLimitedVisibilityFunction` query
+    "cpp/misra/unused-limited-visibility-function" and
+  ruleId = "RULE-0-2-4" and
+  category = "advisory"
+}
+
+module DeadCode10Package {
+  Query unusedLimitedVisibilityFunctionQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `unusedLimitedVisibilityFunction` query
+      TQueryCPP(TDeadCode10PackageQuery(TUnusedLimitedVisibilityFunctionQuery()))
+  }
+}

cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll

@@ -17,6 +17,7 @@ import Const
 import Conversions
 import Conversions2
 import DeadCode
+import DeadCode10
 import DeadCode3
 import DeadCode4
 import Declarations
@@ -89,6 +90,7 @@ newtype TCPPQuery =
   TConversionsPackageQuery(ConversionsQuery q) or
   TConversions2PackageQuery(Conversions2Query q) or
   TDeadCodePackageQuery(DeadCodeQuery q) or
+  TDeadCode10PackageQuery(DeadCode10Query q) or
   TDeadCode3PackageQuery(DeadCode3Query q) or
   TDeadCode4PackageQuery(DeadCode4Query q) or
   TDeclarationsPackageQuery(DeclarationsQuery q) or
@@ -161,6 +163,7 @@ predicate isQueryMetadata(Query query, string queryId, string ruleId, string cat
   isConversionsQueryMetadata(query, queryId, ruleId, category) or
   isConversions2QueryMetadata(query, queryId, ruleId, category) or
   isDeadCodeQueryMetadata(query, queryId, ruleId, category) or
+  isDeadCode10QueryMetadata(query, queryId, ruleId, category) or
   isDeadCode3QueryMetadata(query, queryId, ruleId, category) or
   isDeadCode4QueryMetadata(query, queryId, ruleId, category) or
   isDeclarationsQueryMetadata(query, queryId, ruleId, category) or

cpp/common/src/codingstandards/cpp/rules/unusedlocalfunction/UnusedLocalFunction.qll

@@ -0,0 +1,115 @@
+/**
+ * Provides a configurable module UnusedLocalFunction with a `problems` predicate
+ * for the following issue:
+ * Unused functions may indicate a coding error or require maintenance; functions that
+ * are unused with certain visibility have no effect on the program and should be
+ * removed.
+ */
+
+import cpp
+import codingstandards.cpp.Customizations
+import codingstandards.cpp.Exclusions
+import codingstandards.cpp.DynamicCallGraph
+import codingstandards.cpp.deadcode.UnusedFunctions
+
+/**
+ * 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 f = getTarget(_))
+}
+
+/** Checks if a Function's address was taken. */
+predicate addressBeenTaken(Function unusedFunction) {
+  exists(FunctionAccess fa | fa.getTarget() = unusedFunction)
+}
+
+/** A `Function` nested in an anonymous namespace. */
+class AnonymousNamespaceFunction extends Function {
+  AnonymousNamespaceFunction() { getNamespace().getParentNamespace*().isAnonymous() }
+}
+
+/**
+ * A function which is "local" to a particular scope or translation unit.
+ */
+class LocalFunction extends UnusedFunctions::UsableFunction {
+  string localFunctionType;
+
+  LocalFunction() {
+    this.(MemberFunction).isPrivate() and
+    localFunctionType = "Private member"
+    or
+    // A function in an anonymous namespace (which is deduced to have internal linkage)
+    this instanceof AnonymousNamespaceFunction and
+    not this instanceof MemberFunction and
+    localFunctionType = "Anonymous namespace"
+    or
+    // Class members in anonymous namespaces also have internal linkage.
+    this instanceof AnonymousNamespaceFunction and
+    this instanceof MemberFunction and
+    localFunctionType = "Anonymous namespace class member"
+    or
+    // Static functions with internal linkage
+    this.isStatic() and
+    // Member functions never have internal linkage
+    not this instanceof MemberFunction and
+    // Functions in anonymous namespaces automatically have the "static" specifier added by the
+    // extractor. We therefore excluded them from this case, and instead report them in the
+    // anonymous namespace, as we don't know whether the "static" specifier was explicitly
+    // provided by the user.
+    not this instanceof AnonymousNamespaceFunction and
+    localFunctionType = "Static"
+  }
+
+  /** Gets the type of local function. */
+  string getLocalFunctionType() { result = localFunctionType }
+}
+
+signature module UnusedLocalFunctionConfigSig {
+  Query getQuery();
+}
+
+module UnusedLocalFunction<UnusedLocalFunctionConfigSig Config> {
+  query predicate problems(LocalFunction unusedLocalFunction, string message) {
+    exists(string name |
+      not isExcluded(unusedLocalFunction, Config::getQuery()) and
+      // No static or dynamic call target for this function
+      not unusedLocalFunction = getTarget(_) and
+      // If this is a TemplateFunction or an instantiation of a template, then only report it as unused
+      // if all other instantiations of the template are unused
+      not exists(
+        Function functionFromUninstantiatedTemplate, Function functionFromInstantiatedTemplate
+      |
+        // `unusedLocalFunction` is a template instantiation from `functionFromUninstantiatedTemplate`
+        unusedLocalFunction.isConstructedFrom(functionFromUninstantiatedTemplate)
+        or
+        // `unusedLocalFunction` is from an uninstantiated template
+        unusedLocalFunction = functionFromUninstantiatedTemplate
+      |
+        // There exists an instantiation which is called
+        functionFromInstantiatedTemplate.isConstructedFrom(functionFromUninstantiatedTemplate) and
+        functionFromInstantiatedTemplate = getTarget(_)
+      ) and
+      // A function is defined as "used" if any one of the following holds true:
+      // - It's an explicitly deleted functions e.g. =delete
+      // - It's annotated as "[[maybe_unused]]"
+      // - It's part of an overloaded set and any one of the overloaded instance
+      //   is called.
+      // - It's an operand of an expression in an unevaluated context.
+      not unusedLocalFunction.isDeleted() and
+      not unusedLocalFunction.getAnAttribute().getName() = "maybe_unused" and
+      not overloadedFunctionIsCalled(unusedLocalFunction) and
+      not addressBeenTaken(unusedLocalFunction) and
+      // Get a printable name
+      (
+        if exists(unusedLocalFunction.getQualifiedName())
+        then name = unusedLocalFunction.getQualifiedName()
+        else name = unusedLocalFunction.getName()
+      ) and
+      message =
+        unusedLocalFunction.getLocalFunctionType() + " function " + name +
+          " is not statically called, or is in an unused template."
+    )
+  }
+}

cpp/autosar/test/rules/A0-1-3/UnusedLocalFunction.expected → cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.expected

@@ -4,3 +4,5 @@
 | test.cpp:60:5:60:9 | getAT | Private member function C<T>::getAT is not statically called, or is in an unused template. |
 | test.cpp:81:6:81:7 | h2 | Anonymous namespace function (unnamed namespace)::h2 is not statically called, or is in an unused template. |
 | test.cpp:85:6:85:7 | h3 | Anonymous namespace function (unnamed namespace)::foo::bar::h3 is not statically called, or is in an unused template. |
+| test.cpp:144:8:144:8 | f | Anonymous namespace class member function (unnamed namespace)::C1::f is not statically called, or is in an unused template. |
+| test.cpp:150:8:150:8 | f | Anonymous namespace class member function (unnamed namespace)::named::C2::f is not statically called, or is in an unused template. |

cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.ql

@@ -0,0 +1,8 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.unusedlocalfunction.UnusedLocalFunction
+
+module TestFileConfig implements UnusedLocalFunctionConfigSig {
+  Query getQuery() { result instanceof TestQuery }
+}
+
+import UnusedLocalFunction<TestFileConfig>