Closed #436.

CppCoreGuidelines.md

@@ -7701,15 +7701,28 @@ Check length of local and non-local names. Also take function length into accoun
 
 ##### Reason
 
-Such names slow down comprehension and increase the likelihood of error.
+Code clarity and readability. Too-similar names slow down comprehension and increase the likelihood of error.
 
-##### Example
+##### Example; bad
 
     if (readable(i1 + l1 + ol + o1 + o0 + ol + o1 + I0 + l0)) surprise();
 
+##### Example; bad
+
+Do not declare a non-type with the same name as a type in the same scope. This removes the need to disambiguate with a keyword such as `struct` or `enum`. It also removes a source of errors, as `struct X` can implicitly declare `X` if lookup fails.
+
+    struct foo { int n; };
+    struct foo foo();       // BAD, foo is a type already in scope
+    struct foo x = foo();   // requires disambiguation
+
+##### Exception
+
+Antique header files might declare non-types and types with the same name in the same scope.
+
 ##### Enforcement
+* Check names against a list of known confusing letter and digit combinations.
+* Flag a declaration of a variable, function, or enumerator that hides a class or enumeration declared in the same scope.
 
-Check names against a list of known confusing letter and digit combinations.
 
 ### <a name="Res-not-CAPS"></a> ES.9: Avoid `ALL_CAPS` names