Merge pull request #412 from github/lcartey/a7-1-5-non-fundamental-types

`A7-1-5`: Exclude initializers of a non-fundamental type

Author: lcartey

change_notes/2023-10-24-a7-1-5-non-fundamental.md

@@ -0,0 +1,8 @@
+ * `A7-1-5` - exclude auto variables initialized with an expression of non-fundamental type. Typically this occurs when using range based for loops with arrays of non-fundamental types. For example:
+   ```
+   void iterate(Foo values[]) {
+      for (auto value : values) { // COMPLIANT (previously false positive)
+         // ...
+      }
+   }
+   ```

cpp/autosar/src/rules/A7-1-5/AutoSpecifierNotUsedAppropriatelyInVariableDefinition.ql

@@ -19,6 +19,10 @@
 import cpp
 import codingstandards.cpp.autosar
 
+class FundamentalType extends BuiltInType {
+  FundamentalType() { not this instanceof ErroneousType and not this instanceof UnknownType }
+}
+
 from Variable v
 where
   not isExcluded(v,
@@ -28,12 +32,14 @@ where
   // exclude uninstantiated templates and rely on the instantiated templates, because an uninstantiated template may not contain the information required to determine if the usage is allowed.
   not v.isFromUninstantiatedTemplate(_) and
   not (
-    // find ones where
+    // Initialized by function call
     v.getInitializer().getExpr() instanceof FunctionCall
     or
+    // Initialized by lambda expression
     v.getInitializer().getExpr() instanceof LambdaExpression
     or
-    v.getInitializer().getExpr() instanceof ClassAggregateLiteral
+    // Initialized by non-fundamental type
+    not v.getInitializer().getExpr().getType() instanceof FundamentalType
   ) and
   // Exclude compiler generated variables
   not v.isCompilerGenerated()

cpp/autosar/test/rules/A7-1-5/AutoSpecifierNotUsedAppropriatelyInVariableDefinition.expected

@@ -4,4 +4,4 @@
 | test.cpp:27:8:27:8 | a | Use of auto in variable definition is not the result of a function call, lambda expression, or non-fundamental type initializer. |
 | test.cpp:28:8:28:8 | b | Use of auto in variable definition is not the result of a function call, lambda expression, or non-fundamental type initializer. |
 | test.cpp:81:10:81:10 | a | Use of auto in variable definition is not the result of a function call, lambda expression, or non-fundamental type initializer. |
-| test.cpp:111:19:111:19 | a | Use of auto in variable definition is not the result of a function call, lambda expression, or non-fundamental type initializer. |
+| test.cpp:111:13:111:13 | a | Use of auto in variable definition is not the result of a function call, lambda expression, or non-fundamental type initializer. |

cpp/autosar/test/rules/A7-1-5/test.cpp

@@ -106,9 +106,30 @@ void instantiate() {
   t381.test_381_1();
   t381.test_381_2();
 }
-
+class Foo {};
 void test_loop() {
-  for (const auto a : {8, 9, 10}) {
+  for (auto a : {8, 9, 10}) { // NON_COMPLIANT - a is initialized with a
+                              //                 non-constant initializer
+    a;
+  }
+
+  std::vector<int> v = {1, 2, 3};
+  for (auto &a : v) { // COMPLIANT - a is intialized with a function call
+    a;
+  }
+
+  Foo f1;
+  Foo f2;
+  for (auto &a : {f1, f2}) { // COMPLIANT - initialized with a non-fundamental
+                             //             type
     a;
   }
-}
+}
+
+template <typename T> void test_template(std::vector<T> v2) {
+  for (auto &a : v2) { // COMPLIANT - a is intialized with a function call
+    a;
+  }
+}
+
+void test_template_instantiation() { test_template<int>({1, 2, 3}); }