A2-7-3: fix #606, omit fp in friend function declarations in template classes

Author: knewbury01

change_notes/2024-07-16-fix-fp-606-A2-7-3.md

@@ -0,0 +1,2 @@
+- `A2-7-3` - `UndocumentedUserDefinedType.ql`:
+  - Fixes #606. Fix false positive relating to friend functions in template classes.

cpp/autosar/src/rules/A2-7-3/UndocumentedUserDefinedType.ql

@@ -3,7 +3,7 @@
  * @name A2-7-3: Declarations of 'user-defined' types, member variables and functions should be documented
  * @description All declarations of 'user-defined' types, static and non-static data members,
  *              functions and methods shall be preceded by documentation.
- * @kind problem
+ * @ kind problem
  * @precision very-high
  * @problem.severity recommendation
  * @tags external/autosar/id/a2-7-3
@@ -44,7 +44,11 @@ class DocumentableDeclaration extends Declaration {
     // Exclude instantiated template functions, which cannot reasonably be documented.
     not this.(Function).isFromTemplateInstantiation(_) and
     // Exclude anonymous lambda functions.
-    not exists(LambdaExpression lc | lc.getLambdaFunction() = this)
+    not exists(LambdaExpression lc | lc.getLambdaFunction() = this) and
+    //Exclude friend functions (because they have 2 entries in the database), and only one shows documented truly
+    not exists(FriendDecl d |
+      d.getFriend().(Function).getDefinition() = this.getADeclarationEntry()
+    )
     or
     this instanceof MemberVariable and
     declarationType = "member variable" and

cpp/autosar/test/rules/A2-7-3/UndocumentedUserDefinedType.expected

@@ -7,3 +7,4 @@
 | test.cpp:81:6:81:6 | definition of e | Declaration entry for function e is missing documentation. |
 | test.cpp:88:1:88:30 | definition of message_to_string_undocumented | Declaration entry for function message_to_string_undocumented is missing documentation. |
 | test.cpp:160:21:160:24 | definition of kBar | Declaration entry for member variable kBar is missing documentation. |
+| test.cpp:207:14:207:17 | definition of foo3 | Declaration entry for function foo3 is missing documentation. |

cpp/autosar/test/rules/A2-7-3/test.cpp

@@ -175,4 +175,34 @@ void testFunctionScope() {
       void fNestedTest(); // COMPLIANT - in function scope
     };
   };
-}
+}
+
+/// Test documentation
+template <typename T> class ClassG { // COMPLIANT
+private:
+  /// Test documentation
+  int x; // COMPLIANT
+
+public:
+  /// Test documentation
+  friend int foo(ClassG<T> g) { return g.x; } // COMPLIANT
+};
+
+/// Test documentation
+void test() { // COMPLIANT
+  ClassG<int> g;
+  foo(g);
+}
+
+/// Test documentation
+class ClassG2 { // COMPLIANT
+public:
+  /// Test documentation
+  friend int foo2() { return 1; } // COMPLIANT
+};
+
+/// Test documentation
+class ClassG3 { // COMPLIANT
+public:
+  friend int foo3() { return 1; } // NON_COMPLIANT
+};