Fix #540: A3-9-1: Dont consider variables from template instantiations

change_notes/2024-12-18-fix-fp-540-a3-9-1.md

@@ -0,0 +1,2 @@
+ - `A3-9-1` - `VariableWidthIntegerTypesUsed.ql`:
+   - Reduce false positives by not considering variables from template instantiations.

cpp/autosar/src/rules/A3-9-1/VariableWidthIntegerTypesUsed.ql

@@ -32,6 +32,10 @@ where
     typeStrippedOfSpecifiers instanceof SignedCharType
   ) and
   not v instanceof ExcludedVariable and
+  // Dont consider template instantiations because instantiations with
+  // Fixed Width Types are recorded after stripping their typedef'd type,
+  // thereby, causing false positives (#540).
+  not v.isFromTemplateInstantiation(_) and
   //post-increment/post-decrement operators are required by the standard to have a dummy int parameter
   not v.(Parameter).getFunction() instanceof PostIncrementOperator and
   not v.(Parameter).getFunction() instanceof PostDecrementOperator

cpp/autosar/test/rules/A3-9-1/test.cpp

@@ -75,4 +75,15 @@ void test_variable_width_type_qualified_variables() {
 struct test_fix_fp_614 {
   test_fix_fp_614 operator++(int); // COMPLIANT
   test_fix_fp_614 operator--(int); // COMPLIANT
-};
+};
+
+// COMPLIANT - instantiated with Fixed Width Types.
+template <typename MyType> constexpr void test_fix_fp_540(MyType value) {
+  value++;
+}
+
+int call_test_fix_fp_540() {
+  test_fix_fp_540<std::uint8_t>(19);
+  test_fix_fp_540<std::int16_t>(20);
+  return 0;
+}