Alexander Udalov
1d5d6b5b72
Preface: Kotlin 1.3 will be able to read metadata of .class files produced by Kotlin 1.4 (see KT-25972). Also, to simplify implementation and to improve diagnostic messages, we're going to advance JVM metadata version to 1.4.0 in Kotlin 1.4, and would like to keep it in sync with the compiler version thereafter. This presents a problem: in an unlikely event that before releasing 1.4, we find out that the metadata-reading implementation in 1.3 was incorrect, we'd like to be able to fix the bug in that implementation and _forbid_ 1.3 from reading metadata of 1.4. But prior to this commit the only way to do this was to advance the metadata version, in this case to 1.5, and that breaks the metadata/compiler version equivalence we'd like to keep. The solution is to add another boolean flag to the class file, called "strict metadata version semantics", which signifies that if this class file has metadata version 1.X, then it can only be read by the compilers of versions 1.X and greater. This flag effectively disables the smooth migration scenario proposed in KT-25972 (as does increasing metadata version by 2), and will be used only in hopeless situations as in the case described above.
The Kotlin Standard Library
This module creates the standard library for Kotlin.
Notes for contributors
We use some code generation to generate the various utility extension function for the various collection-like types like arrays, strings, Collection<T>, Sequence<T>, Map<K, V> etc.
These sources are placed into generated folder and their names are prefixed with the underscore, for example generated/_Collections.kt
To run the code generator use the following command in the root directory of the project:
./gradlew :tools:kotlin-stdlib-gen:run
Note: on Windows type
gradlewwithout the leading./
This then runs the script which generates a significant part of stdlib sources from the templates authored with a special kotlin based DSL.
Usage samples
If you want to author samples for the standard library, please head to the samples readme.