val extraInt: Int

An extra int. Bits of this number represent the following flags:

  • 0 - this is a multi-file class facade or part, compiled with -Xmultifile-parts-inherit.
  • 1 - this class file is compiled by a pre-release version of Kotlin and is not visible to release versions.
  • 2 - this class file is a compiled Kotlin script source file (.kts).
  • 3 - "strict metadata version semantics". The metadata of this class file is not supposed to be read by the compiler, whose major.minor version is less than the major.minor version of this metadata (metadataVersion).
  • 4 - this class file is compiled with the new Kotlin compiler backend (JVM IR) introduced in Kotlin 1.4.
  • 5 - this class file has stable metadata and ABI. This is used only for class files compiled with JVM IR (see flag #4) or FIR (#6), and prevents metadata incompatibility diagnostics from being reported where the class is used.
  • 6 - this class file is compiled with the K2 compiler frontend (FIR). Only valid before metadata version 2.0.0. Starting from metadata version 2.0.0, this flag is not set anymore, even though FIR is always used.
  • 7 - this class is used in the scope of an inline function and implicitly part of the public ABI. Only valid from metadata version 1.6.0.