enum-no-allow-alias (Protobuf linter rule)

enum-no-allow-alias

Since 0.9.0

This rule checks whether any enum sets the allow_alias option.

Rule Details

With option allow_alias = true;, several values of an enum can share a number. Only one of the names survives serialization, though: the JSON and text formats always write the first name of the number, so a client that sends one name may read back another. Aliases also make renaming values harder than it looks, since both names have to be kept in sync with every consumer.

The enum-no-allow-alias rule reports Enum '<enum>' should not allow aliases at the allow_alias option of every enum that sets it to true.

Configuration

This rule has no options.

Examples

Good.

syntax = "proto3";

package acme.pets.v1;

enum PetKind {
  PET_KIND_UNSPECIFIED = 0;
  PET_KIND_DOG = 1;
  PET_KIND_CAT = 2;
}

Bad. The linter reports Enum 'PetKind' should not allow aliases.

syntax = "proto3";

package acme.pets.v1;

enum PetKind {
  option allow_alias = true;
  PET_KIND_UNSPECIFIED = 0;
  PET_KIND_DOG = 1;
  PET_KIND_HOUND = 1;
  PET_KIND_CAT = 2;
}

When Not to Use It

You may disable this rule while renaming enum values: an alias lets the old and the new name coexist until all clients have moved to the new one. To allow a single enum, add an // apigenie-lint-disable enum-no-allow-alias comment to the enum.

Compatibility