github · knewbury01 · Mar 27, 2026
diff --git a/c/cert/src/rules/DCL40-C/ExternalIdentifiers.qll b/c/cert/src/rules/DCL40-C/ExternalIdentifiers.qll
diff --git a/c/cert/src/rules/DCL40-C/IncompatibleFunctionDeclarations.ql b/c/cert/src/rules/DCL40-C/IncompatibleFunctionDeclarations.ql
@@ -21,42 +21,11 @@
 
 import cpp
 import codingstandards.c.cert
-import codingstandards.cpp.types.Compatible
-import ExternalIdentifiers
+import codingstandards.cpp.rules.incompatiblefunctiondeclaration.IncompatibleFunctionDeclaration
 
-predicate interestedInFunctions(
-  FunctionDeclarationEntry f1, FunctionDeclarationEntry f2, ExternalIdentifiers d
-) {
-  not f1 = f2 and
-  d = f1.getDeclaration() and
-  d = f2.getDeclaration()
+module IncompatibleFunctionDeclarationsCppConfig implements IncompatibleFunctionDeclarationConfigSig
+{
+  Query getQuery() { result = Declarations2Package::incompatibleFunctionDeclarationsQuery() }
 }
 
-predicate interestedInFunctions(FunctionDeclarationEntry f1, FunctionDeclarationEntry f2) {
-  interestedInFunctions(f1, f2, _)
-}
-
-module FuncDeclEquiv =
-  FunctionDeclarationTypeEquivalence<TypesCompatibleConfig, interestedInFunctions/2>;
-
-from ExternalIdentifiers d, FunctionDeclarationEntry f1, FunctionDeclarationEntry f2
-where
-  not isExcluded(f1, Declarations2Package::incompatibleFunctionDeclarationsQuery()) and
-  not isExcluded(f2, Declarations2Package::incompatibleFunctionDeclarationsQuery()) and
-  interestedInFunctions(f1, f2, d) and
-  (
-    //return type check
-    not FuncDeclEquiv::equalReturnTypes(f1, f2)
-    or
-    //parameter type check
-    not FuncDeclEquiv::equalParameterTypes(f1, f2)
-  ) and
-  // Apply ordering on start line, trying to avoid the optimiser applying this join too early
-  // in the pipeline
-  exists(int f1Line, int f2Line |
-    f1.getLocation().hasLocationInfo(_, f1Line, _, _, _) and
-    f2.getLocation().hasLocationInfo(_, f2Line, _, _, _) and
-    f1Line >= f2Line
-  )
-select f1, "The object $@ is not compatible with re-declaration $@", f1, f1.getName(), f2,
-  f2.getName()
+import IncompatibleFunctionDeclaration<IncompatibleFunctionDeclarationsCppConfig>
diff --git a/c/cert/src/rules/DCL40-C/IncompatibleObjectDeclarations.ql b/c/cert/src/rules/DCL40-C/IncompatibleObjectDeclarations.ql
@@ -3,7 +3,7 @@
  * @name DCL40-C: Do not create incompatible declarations of the same function or object
  * @description Declaring incompatible objects, in other words same named objects of different
  *              types, then accessing those objects can lead to undefined behaviour.
- * @kind problem
+ * @ kind problem
  * @precision high
  * @problem.severity error
  * @tags external/cert/id/dcl40-c
@@ -20,16 +20,10 @@
 
 import cpp
 import codingstandards.c.cert
-import ExternalIdentifiers
+import codingstandards.cpp.rules.incompatibleobjectdeclaration.IncompatibleObjectDeclaration
 
-from VariableDeclarationEntry decl1, VariableDeclarationEntry decl2
-where
-  not isExcluded(decl1, Declarations2Package::incompatibleObjectDeclarationsQuery()) and
-  not isExcluded(decl2, Declarations2Package::incompatibleObjectDeclarationsQuery()) and
-  not decl1.getUnspecifiedType() = decl2.getUnspecifiedType() and
-  decl1.getDeclaration() instanceof ExternalIdentifiers and
-  decl2.getDeclaration() instanceof ExternalIdentifiers and
-  decl1.getLocation().getStartLine() >= decl2.getLocation().getStartLine() and
-  decl1.getVariable().getName() = decl2.getVariable().getName()
-select decl1, "The object $@ is not compatible with re-declaration $@", decl1, decl1.getName(),
-  decl2, decl2.getName()
+module IncompatibleObjectDeclarationsCppConfig implements IncompatibleObjectDeclarationConfigSig {
+  Query getQuery() { result = Declarations2Package::incompatibleObjectDeclarationsQuery() }
+}
+
+import IncompatibleObjectDeclaration<IncompatibleObjectDeclarationsCppConfig>
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.expected b/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.expected
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.qlref b/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.qlref
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.testref b/c/cert/test/rules/DCL40-C/IncompatibleFunctionDeclarations.testref
@@ -0,0 +1 @@
+c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.expected b/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.expected
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.qlref b/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.qlref
diff --git a/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.testref b/c/cert/test/rules/DCL40-C/IncompatibleObjectDeclarations.testref
@@ -0,0 +1 @@
+c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.ql
diff --git a/c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.expected b/c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.expected
@@ -0,0 +1,4 @@
+| test1.c:4:12:4:12 | declaration of f | The object is not compatible with a re-declaration $@. | test.c:4:6:4:6 | definition of f | f |
+| test.c:4:6:4:6 | definition of f | The object is not compatible with a re-declaration $@. | test1.c:4:12:4:12 | declaration of f | f |
+| test.c:8:6:8:7 | declaration of f1 | The object is not compatible with a re-declaration $@. | test1.c:5:13:5:14 | declaration of f1 | f1 |
+| test.c:9:6:9:7 | definition of f2 | The object is not compatible with a re-declaration $@. | test1.c:6:6:6:7 | definition of f2 | f2 |
diff --git a/c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql b/c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql
@@ -0,0 +1,8 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.incompatiblefunctiondeclaration.IncompatibleFunctionDeclaration
+
+module TestFileConfig implements IncompatibleFunctionDeclarationConfigSig {
+  Query getQuery() { result instanceof TestQuery }
+}
+
+import IncompatibleFunctionDeclaration<TestFileConfig>
diff --git a/c/cert/test/rules/DCL40-C/test.c → ...es/incompatiblefunctiondeclaration/test.c b/c/cert/test/rules/DCL40-C/test.c → ...es/incompatiblefunctiondeclaration/test.c
diff --git a/c/cert/test/rules/DCL40-C/test1.c → ...s/incompatiblefunctiondeclaration/test1.c b/c/cert/test/rules/DCL40-C/test1.c → ...s/incompatiblefunctiondeclaration/test1.c
diff --git a/c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.expected b/c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.expected
@@ -0,0 +1,2 @@
+| test1.c:2:12:2:12 | declaration of i | The object is not compatible with a re-declaration $@. | test.c:1:7:1:7 | definition of i | i |
+| test.c:2:5:2:5 | definition of a | The object is not compatible with a re-declaration $@. | test1.c:1:13:1:13 | declaration of a | a |
diff --git a/c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.ql b/c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.ql
@@ -0,0 +1,8 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.incompatibleobjectdeclaration.IncompatibleObjectDeclaration
+
+module TestFileConfig implements IncompatibleObjectDeclarationConfigSig {
+  Query getQuery() { result instanceof TestQuery }
+}
+
+import IncompatibleObjectDeclaration<TestFileConfig>
diff --git a/c/common/test/rules/incompatibleobjectdeclaration/test.c b/c/common/test/rules/incompatibleobjectdeclaration/test.c
@@ -0,0 +1,10 @@
+short i;                // NON_COMPLIANT
+int a[] = {1, 2, 3, 4}; // NON_COMPLIANT
+
+long f(int a) { // NON_COMPLIANT
+  return a * 2;
+}
+
+void f1(long a); // NON_COMPLIANT
+void f2() {}     // NON_COMPLIANT
+int f3();        // COMPLIANT
diff --git a/c/common/test/rules/incompatibleobjectdeclaration/test1.c b/c/common/test/rules/incompatibleobjectdeclaration/test1.c
@@ -0,0 +1,7 @@
+extern int *a; // NON_COMPLIANT
+extern int i;  // NON_COMPLIANT
+
+extern int f(int a);   // NON_COMPLIANT
+extern void f1(int a); // NON_COMPLIANT
+void f2(int a, ...) {} // NON_COMPLIANT
+int f3();              // COMPLIANT
diff --git a/change_notes/2026-03-27-update-compatible-objects-DCL40-C.md b/change_notes/2026-03-27-update-compatible-objects-DCL40-C.md
@@ -0,0 +1,2 @@
+ - `DCL40-C` - `IncompatibleObjectDeclarations.ql`:
+   - Enhanced the query's ability to compare objects with array type, which will reduce false positives.
diff --git a/cpp/common/src/codingstandards/cpp/exclusions/cpp/Declarations2.qll b/cpp/common/src/codingstandards/cpp/exclusions/cpp/Declarations2.qll
@@ -0,0 +1,61 @@
+//** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY.  **/
+import cpp
+import RuleMetadata
+import codingstandards.cpp.exclusions.RuleMetadata
+
+newtype Declarations2Query =
+  TIncompatibleObjectDeclarationsCppQuery() or
+  TIncompatibleFunctionDeclarationsCppQuery() or
+  TLocalVariableStaticStorageDurationQuery()
+
+predicate isDeclarations2QueryMetadata(Query query, string queryId, string ruleId, string category) {
+  query =
+    // `Query` instance for the `incompatibleObjectDeclarationsCpp` query
+    Declarations2Package::incompatibleObjectDeclarationsCppQuery() and
+  queryId =
+    // `@id` for the `incompatibleObjectDeclarationsCpp` query
+    "cpp/misra/incompatible-object-declarations-cpp" and
+  ruleId = "RULE-6-2-2" and
+  category = "required"
+  or
+  query =
+    // `Query` instance for the `incompatibleFunctionDeclarationsCpp` query
+    Declarations2Package::incompatibleFunctionDeclarationsCppQuery() and
+  queryId =
+    // `@id` for the `incompatibleFunctionDeclarationsCpp` query
+    "cpp/misra/incompatible-function-declarations-cpp" and
+  ruleId = "RULE-6-2-2" and
+  category = "required"
+  or
+  query =
+    // `Query` instance for the `localVariableStaticStorageDuration` query
+    Declarations2Package::localVariableStaticStorageDurationQuery() and
+  queryId =
+    // `@id` for the `localVariableStaticStorageDuration` query
+    "cpp/misra/local-variable-static-storage-duration" and
+  ruleId = "RULE-6-7-1" and
+  category = "required"
+}
+
+module Declarations2Package {
+  Query incompatibleObjectDeclarationsCppQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `incompatibleObjectDeclarationsCpp` query
+      TQueryCPP(TDeclarations2PackageQuery(TIncompatibleObjectDeclarationsCppQuery()))
+  }
+
+  Query incompatibleFunctionDeclarationsCppQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `incompatibleFunctionDeclarationsCpp` query
+      TQueryCPP(TDeclarations2PackageQuery(TIncompatibleFunctionDeclarationsCppQuery()))
+  }
+
+  Query localVariableStaticStorageDurationQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `localVariableStaticStorageDuration` query
+      TQueryCPP(TDeclarations2PackageQuery(TLocalVariableStaticStorageDurationQuery()))
+  }
+}
diff --git a/cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll b/cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll
@@ -30,6 +30,7 @@ import DeadCode8
 import DeadCode9
 import Declarations
 import Declarations1
+import Declarations2
 import ExceptionSafety
 import Exceptions1
 import Exceptions2
@@ -123,6 +124,7 @@ newtype TCPPQuery =
   TDeadCode9PackageQuery(DeadCode9Query q) or
   TDeclarationsPackageQuery(DeclarationsQuery q) or
   TDeclarations1PackageQuery(Declarations1Query q) or
+  TDeclarations2PackageQuery(Declarations2Query q) or
   TExceptionSafetyPackageQuery(ExceptionSafetyQuery q) or
   TExceptions1PackageQuery(Exceptions1Query q) or
   TExceptions2PackageQuery(Exceptions2Query q) or
@@ -216,6 +218,7 @@ predicate isQueryMetadata(Query query, string queryId, string ruleId, string cat
   isDeadCode9QueryMetadata(query, queryId, ruleId, category) or
   isDeclarationsQueryMetadata(query, queryId, ruleId, category) or
   isDeclarations1QueryMetadata(query, queryId, ruleId, category) or
+  isDeclarations2QueryMetadata(query, queryId, ruleId, category) or
   isExceptionSafetyQueryMetadata(query, queryId, ruleId, category) or
   isExceptions1QueryMetadata(query, queryId, ruleId, category) or
   isExceptions2QueryMetadata(query, queryId, ruleId, category) or

diff --git a/...ngstandards/cpp/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.qll b/...ngstandards/cpp/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.qll
@@ -0,0 +1,62 @@
+/**
+ * Provides a configurable module IncompatibleFunctionDeclaration with a `problems` predicate
+ * for the following issue:
+ * Declaring incompatible functions, in other words same named function of different
+ * return types or with different numbers of parameters or parameter types, then
+ * accessing those functions can lead to undefined behaviour.
+ */
+
+import cpp
+import codingstandards.cpp.Customizations
+import codingstandards.cpp.Exclusions
+import codingstandards.cpp.Identifiers
+import codingstandards.cpp.types.Compatible
+
+predicate interestedInFunctions(
+  FunctionDeclarationEntry f1, FunctionDeclarationEntry f2, ExternalIdentifiers d1,
+  ExternalIdentifiers d2
+) {
+  not f1 = f2 and
+  d1 = f1.getDeclaration() and
+  d2 = f2.getDeclaration() and
+  f1.getName() = f2.getName()
+}
+
+predicate interestedInFunctions(FunctionDeclarationEntry f1, FunctionDeclarationEntry f2) {
+  interestedInFunctions(f1, f2, _, _)
+}
+
+module FuncDeclEquiv =
+  FunctionDeclarationTypeEquivalence<TypesCompatibleConfig, interestedInFunctions/2>;
+
+signature module IncompatibleFunctionDeclarationConfigSig {
+  Query getQuery();
+}
+
+module IncompatibleFunctionDeclaration<IncompatibleFunctionDeclarationConfigSig Config> {
+  query predicate problems(
+    FunctionDeclarationEntry f1, string message, FunctionDeclarationEntry f2, string secondMessage
+  ) {
+    exists(ExternalIdentifiers d1, ExternalIdentifiers d2 |
+      not isExcluded(f1, Config::getQuery()) and
+      not isExcluded(f2, Config::getQuery()) and
+      interestedInFunctions(f1, f2, d1, d2) and
+      (
+        //return type check
+        not FuncDeclEquiv::equalReturnTypes(f1, f2)
+        or
+        //parameter type check
+        not FuncDeclEquiv::equalParameterTypes(f1, f2)
+      ) and
+      // Apply ordering on start line, trying to avoid the optimiser applying this join too early
+      // in the pipeline
+      exists(int f1Line, int f2Line |
+        f1.getLocation().hasLocationInfo(_, f1Line, _, _, _) and
+        f2.getLocation().hasLocationInfo(_, f2Line, _, _, _) and
+        f1Line >= f2Line
+      ) and
+      secondMessage = f2.getName() and
+      message = "The object is not compatible with a re-declaration $@."
+    )
+  }
+}
diff --git a/...codingstandards/cpp/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.qll b/...codingstandards/cpp/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.qll
@@ -0,0 +1,44 @@
+/**
+ * Provides a configurable module IncompatibleObjectDeclaration with a `problems` predicate
+ * for the following issue:
+ * Declaring incompatible objects, in other words same named objects of different
+ * types, then accessing those objects can lead to undefined behavior.
+ */
+
+import cpp
+import codingstandards.cpp.Customizations
+import codingstandards.cpp.Exclusions
+import codingstandards.cpp.Identifiers
+import codingstandards.cpp.types.Compatible
+
+signature module IncompatibleObjectDeclarationConfigSig {
+  Query getQuery();
+}
+
+predicate relevantTypes(Type a, Type b) {
+  exists(VariableDeclarationEntry varA, VariableDeclarationEntry varB |
+    not varA = varB and
+    varA.getVariable().getName() = varB.getVariable().getName() and
+    a = varA.getType() and
+    b = varB.getType()
+  )
+}
+
+module IncompatibleObjectDeclaration<IncompatibleObjectDeclarationConfigSig Config> {
+  query predicate problems(
+    VariableDeclarationEntry decl1, string message, VariableDeclarationEntry decl2,
+    string secondMessage
+  ) {
+    not isExcluded(decl1, Config::getQuery()) and
+    not isExcluded(decl2, Config::getQuery()) and
+    not TypeEquivalence<TypesCompatibleConfig, relevantTypes/2>::equalTypes(decl1.getType(),
+      decl2.getType()) and
+    not decl1 = decl2 and
+    decl1.getDeclaration() instanceof ExternalIdentifiers and
+    decl2.getDeclaration() instanceof ExternalIdentifiers and
+    decl1.getLocation().getStartLine() >= decl2.getLocation().getStartLine() and
+    decl1.getVariable().getName() = decl2.getVariable().getName() and
+    secondMessage = decl2.getName() and
+    message = "The object is not compatible with a re-declaration $@."
+  }
+}
diff --git a/...ommon/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.expected b/...ommon/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.expected
@@ -0,0 +1,5 @@
+| test1.cpp:1:12:1:12 | declaration of f | The object is not compatible with a re-declaration $@. | test.cpp:1:6:1:6 | definition of f | f |
+| test.cpp:1:6:1:6 | definition of f | The object is not compatible with a re-declaration $@. | test1.cpp:1:12:1:12 | declaration of f | f |
+| test.cpp:5:6:5:7 | declaration of f1 | The object is not compatible with a re-declaration $@. | test1.cpp:2:13:2:14 | declaration of f1 | f1 |
+| test.cpp:6:6:6:7 | definition of f2 | The object is not compatible with a re-declaration $@. | test1.cpp:3:6:3:7 | definition of f2 | f2 |
+| test.cpp:9:17:9:18 | declaration of f4 | The object is not compatible with a re-declaration $@. | test1.cpp:6:17:6:18 | declaration of f4 | f4 |
diff --git a/cpp/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql b/cpp/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql
@@ -0,0 +1,8 @@
+// GENERATED FILE - DO NOT MODIFY
+import codingstandards.cpp.rules.incompatiblefunctiondeclaration.IncompatibleFunctionDeclaration
+
+module TestFileConfig implements IncompatibleFunctionDeclarationConfigSig {
+  Query getQuery() { result instanceof TestQuery }
+}
+
+import IncompatibleFunctionDeclaration<TestFileConfig>
diff --git a/cpp/common/test/rules/incompatiblefunctiondeclaration/test.cpp b/cpp/common/test/rules/incompatiblefunctiondeclaration/test.cpp
@@ -0,0 +1,10 @@
+long f(int a) { // NON_COMPLIANT
+  return a * 2;
+}
+
+void f1(long a); // NON_COMPLIANT
+void f2() {}     // NON_COMPLIANT
+int f3();        // COMPLIANT
+
+extern "C" long f4(int a); // NON_COMPLIANT
+long f5();                 // NON_COMPLIANT[FALSE_NEGATIVE]
diff --git a/cpp/common/test/rules/incompatiblefunctiondeclaration/test1.cpp b/cpp/common/test/rules/incompatiblefunctiondeclaration/test1.cpp
@@ -0,0 +1,7 @@
+extern int f(int a);   // NON_COMPLIANT
+extern void f1(int a); // NON_COMPLIANT
+void f2(int a, ...) {} // NON_COMPLIANT
+int f3();              // COMPLIANT
+
+extern "C" long f4(char a); // NON_COMPLIANT
+long f5() noexcept;         // NON_COMPLIANT[FALSE_NEGATIVE]
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		c/common/test/rules/incompatiblefunctiondeclaration/IncompatibleFunctionDeclaration.ql
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		c/common/test/rules/incompatibleobjectdeclaration/IncompatibleObjectDeclaration.ql
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		\| test1.c:2:12:2:12 \| declaration of i \| The object is not compatible with a re-declaration $@. \| test.c:1:7:1:7 \| definition of i \| i \|
		\| test.c:2:5:2:5 \| definition of a \| The object is not compatible with a re-declaration $@. \| test1.c:1:13:1:13 \| declaration of a \| a \|
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		- `DCL40-C` - `IncompatibleObjectDeclarations.ql`:
		- Enhanced the query's ability to compare objects with array type, which will reduce false positives.