jeremyrsmith / mima-cli   0.1.0

Apache License 2.0 GitHub

Command line interface for MiMa, the Scala Migration Manager

Scala versions: 2.13


This is a command-line interface over MiMa. You can use it to generate a report of binary incompatibility issues that are introduced between two versions of a Scala libarary.

It is neither endorsed nor supported by Lightbend. All it does is invoke MiMa.


Each GitHub release has an assembly JAR attached to it, which should be directly executable. So just download it, name it mima-cli and put it somewhere in your PATH.

Alternatively, it's also released to Maven Central, so you can probably use Coursier's bootstrap command instead.


mima [OPTIONS] oldfile newfile

  oldfile: Old (or, previous) files – a JAR or a directory containing classfiles
  newfile: New (or, current) files - a JAR or a directory containing classfiles
     Specify Java classpath, separated by '${File.pathSeparatorChar}'
  -v, --verbose:
     Show a human-readable description of each problem
  -f, --forward-only:
    Show only forward-binary-compatibility problems
  -b, --backward-only:
    Show only backward-binary-compatibility problems
  -g, --include-generics:
    Include generic signature problems, which may not directly cause bincompat
    problems and are hidden by default. Has no effect if using --forward-only.
  -j, --bytecode-names:
    Show bytecode names of fields and methods, rather than human-readable names


If there are no binary incompatibilities to report, mima-cli prints nothing and exits with 0 status. Otherwise, it exits with a status representing the number of binary compatibility problems, after printing a report of the problems to stdout.

Here's a sample of default output, on two old versions of circe (I had to reach pretty far back to find any examples of binary incompatibility!)

$ mima-cli circe-core_2.12-0.9.0.jar circe-core_2.12-0.10.0.jar
io.circe.ACursor.fieldSet: DirectMissingMethod
io.circe.ACursor.fields: DirectMissingMethod
io.circe.Decoder.decodeTraversable: DirectMissingMethod
io.circe.Decoder.and: DirectMissingMethod
io.circe.Decoder.split: DirectMissingMethod
io.circe.Decoder.decodeTraversable: DirectMissingMethod
io.circe.Decoder#DecoderWithFailure.and: DirectMissingMethod
io.circe.Decoder#DecoderWithFailure.split: DirectMissingMethod
io.circe.Encoder.importedEncoder: IncompatibleMethType
io.circe.Encoder.importedEncoder: IncompatibleMethType
io.circe.JsonNumber.truncateToByte: DirectMissingMethod
io.circe.JsonNumber.truncateToShort: DirectMissingMethod
io.circe.JsonNumber.truncateToInt: DirectMissingMethod
io.circe.JsonNumber.truncateToLong: DirectMissingMethod
io.circe.JsonObject.from: DirectMissingMethod
io.circe.JsonObject.fields: DirectMissingMethod
io.circe.JsonObject.fieldSet: DirectMissingMethod
io.circe.JsonObject.withJsons: DirectMissingMethod
io.circe.JsonObject.from: DirectMissingMethod
io.circe.RootEncoder.importedRootEncoder: IncompatibleMethType
io.circe.RootEncoder.importedRootEncoder: IncompatibleMethType

And a few lines of the corresponding --verbose output:

$ mima-cli -v circe-core_2.12-0.9.0.jar circe-core_2.12-0.10.0.jar
io.circe.ACursor.fieldSet: DirectMissingMethod: deprecated method fieldSet()scala.Option in class io.circe.ACursor does not have a correspondent in new version
io.circe.ACursor.fields: DirectMissingMethod: deprecated method fields()scala.Option in class io.circe.ACursor does not have a correspondent in new version
io.circe.Decoder.decodeTraversable: DirectMissingMethod: static method decodeTraversable(io.circe.Decoder,scala.collection.generic.CanBuildFrom)io.circe.Decoder in interface io.circe.Decoder does not have a correspondent in new version

And, a few lines of the corresponding --bytecode-names output (this is intended for use in other classfile tooling, like javap):

$ mima-cli -j circe-core_2.12-0.9.0.jar circe-core_2.12-0.10.0.jar
io/circe/ACursor.fieldSet()Lscala.Option;: DirectMissingMethod
io/circe/ACursor.fields()Lscala.Option;: DirectMissingMethod
io/circe/Decoder.decodeTraversable(Lio.circe.Decoder;Lscala.collection.generic.CanBuildFrom;)Lio.circe.Decoder;: DirectMissingMethod


It's under the Apache 2.0 License, because that's what MiMA has. Click here for MiMa's license.