Avoid similar-looking names

Reason

Code clarity and readability. Too-similar names slow down comprehension and increase the likelihood of error.

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.