readability-enum-initial-value

Enforces consistent style for enumerators’ initialization, covering three styles: none, first only, or all initialized explicitly.

When adding new enumerations, inconsistent initial value will cause potential enumeration value conflicts.

In an enumeration, the following three cases are accepted. 1. none of enumerators are explicit initialized. 2. the first enumerator is explicit initialized. 3. all of enumerators are explicit initialized.

// valid, none of enumerators are initialized.
enum A {
  e0,
  e1,
  e2,
};

// valid, the first enumerator is initialized.
enum A {
  e0 = 0,
  e1,
  e2,
};

// valid, all of enumerators are initialized.
enum A {
  e0 = 0,
  e1 = 1,
  e2 = 2,
};

// invalid, e1 is not explicit initialized.
enum A {
  e0 = 0,
  e1,
  e2 = 2,
};

Options

AllowExplicitZeroFirstInitialValue

If set to false, the first enumerator must not be explicitly initialized. See examples below. Default is true.

enum A {
  e0 = 0, // not allowed if AllowExplicitZeroFirstInitialValue is false
  e1,
  e2,
};

AllowExplicitSequentialInitialValues

If set to false, sequential initializations are not allowed. See examples below. Default is true.

enum A {
  e0 = 1, // not allowed if AllowExplicitSequentialInitialValues is false
  e1 = 2,
  e2 = 3,
};