IdentifierHidden: reduce FN case and remove redundant testcase

Author: knewbury01

cpp/common/src/codingstandards/cpp/rules/identifierhidden/IdentifierHidden.qll

@@ -13,12 +13,14 @@ abstract class IdentifierHiddenSharedQuery extends Query { }
 Query getQuery() { result instanceof IdentifierHiddenSharedQuery }
 
 /**
- * a `IntegralOrEnumType` that is nonvolatile and const
+ * a `Variable` that is nonvolatile and const
+ * and of type `IntegralOrEnumType`
  */
-class NonVolatileConstIntegralOrEnumType extends IntegralOrEnumType {
-  NonVolatileConstIntegralOrEnumType() {
+class NonVolatileConstIntegralOrEnumVariable extends Variable {
+  NonVolatileConstIntegralOrEnumVariable() {
     not this.isVolatile() and
-    this.isConst()
+    this.isConst() and
+    this.getUnspecifiedType() instanceof IntegralOrEnumType
   }
 }
 
@@ -59,7 +61,7 @@ predicate hiddenInLambda(UserVariable outerDecl, UserVariable innerDecl) {
       exists(outerDecl.getInitializer().getExpr().getValue())
       or
       //it const non-volatile integral or enumeration type and has been initialized with a constant expression
-      outerDecl.getType() instanceof NonVolatileConstIntegralOrEnumType and
+      outerDecl instanceof NonVolatileConstIntegralOrEnumVariable and
       exists(outerDecl.getInitializer().getExpr().getValue())
       or
       //it is constexpr and has no mutable members

cpp/common/test/rules/identifierhidden/IdentifierHidden.expected

@@ -15,3 +15,4 @@
 | test.cpp:142:9:142:10 | a1 | Declaration is hiding declaration $@. | test.cpp:140:14:140:15 | a1 | a1 |
 | test.cpp:147:9:147:10 | a2 | Declaration is hiding declaration $@. | test.cpp:145:20:145:21 | a2 | a2 |
 | test.cpp:152:9:152:10 | a3 | Declaration is hiding declaration $@. | test.cpp:150:17:150:18 | a3 | a3 |
+| test.cpp:164:9:164:10 | a5 | Declaration is hiding declaration $@. | test.cpp:162:13:162:14 | a5 | a5 |

cpp/common/test/rules/identifierhidden/test.cpp

@@ -161,7 +161,7 @@ void f8() {
 
   const int a5 = 10;
   auto lambda5 = []() {
-    int a5 = a5 + 1; // NON_COMPLIANT[FALSE_NEGATIVE] - Lambda can access const
+    int a5 = a5 + 1; // NON_COMPLIANT - Lambda can access const
                      // non-volatile integral or enumeration type initialized
                      // with constant expression.
   };
@@ -172,12 +172,4 @@ void f8() {
         a6 + 1; // COMPLIANT - Lambda cannot access const volatile integral or
                 // enumeration type initialized with constant expression.
   };
-}
-
-void f9() {
-  auto lambda1 = []() {
-    int a1 = 10; // COMPLIANT
-  };
-
-  int a1 = 10;
 }