A7-1-2: Exclude generated variables and variables in uninstantiated templates.

Author: lcartey

change_notes/2024-06-03-constexpr-variable.md

@@ -0,0 +1,3 @@
+ - `A7-1-2` - `VariableMissingConstexpr.ql`:
+   - Remove false positives for compiler generated variables
+   - Remove results in uninstantiated templates that cause false positives

cpp/autosar/src/rules/A7-1-2/VariableMissingConstexpr.ql

@@ -62,5 +62,9 @@ where
   // Not assigned by a user in a constructor
   not exists(ConstructorFieldInit cfi | cfi.getTarget() = v and not cfi.isCompilerGenerated()) and
   // Ignore union members
-  not v.getDeclaringType() instanceof Union
+  not v.getDeclaringType() instanceof Union and
+  // Exclude variables in uninstantiated templates, as they may be incomplete
+  not v.isFromUninstantiatedTemplate(_) and
+  // Exclude compiler generated variables, which are not user controllable
+  not v.isCompilerGenerated()
 select v, "Variable " + v.getName() + " could be marked 'constexpr'."

cpp/autosar/test/rules/A7-1-2/test.cpp

@@ -264,4 +264,16 @@ constexpr void fp_reported_in_466(int p) {
                      // compile time constant
   int l26 =
       add4(1, l3); // COMPLIANT - l3 is not compile time constant on all paths
+}
+
+template <typename T> T* init(T** t) { }
+
+template <typename T> T* init() {
+ T* t = nullptr; // COMPLIANT - initialized below
+ init(&t); // Init is ignored in uninitialized template
+ return t;
+}
+
+void test_template_instantiation() {
+  int* t = init<int>();
 }