TastyVersionCompatibility

This method implements a binary relation (<:<) between two TASTy versions.

Given the TASTy version of a file and the TASTy version of the compiler, if file <:< compiler then the TASTy file is valid to be read.

A TASTy version, e.g. v := 28.0-3 is composed of three fields:

• v.major == 28
• v.minor == 0
• v.experimental == 3

TASTy versions have a partial order, for example, a <:< b and b <:< a are both false if

• a and b have different major fields.
• a and b have the same major & minor fields, but different, non-zero, experimental fields.

A TASTy version with a zero value for its experimental field is considered to be stable. Files with a stable TASTy version can be read by a compiler with an unstable TASTy version, (where the compiler's TASTy version has a higher minor field).

A compiler with a stable TASTy version can never read a file with an unstable TASTy version.

We follow the given algorithm:

file match
  case (MajorVersion, MinorVersion, ExperimentalVersion) => true // full equality
  case (MajorVersion, minor, 0) if minor < MinorVersion  => true // stable backwards compatibility
  case _                                                 => false