The point here is to disable the "checkNotNewerThanCompiler" check because it
breaks a real life use case of compiling with an old compiler against the new
runtime library (that may come implicitly as a transitive dependency of another
library). However, to keep the possibility of restoring this check in the
future without backporting the needed changes into the old branches, we now
only perform this check for the "Core" runtime components, and all other checks
-- for "Core" and "Main" runtime components. In the follow-up commit, we change
the runtime component of our libraries to "Main". If we decide we need the
"checkNotNewerThanCompiler" behavior in the future, we can change the runtime
component to "Core", effectively restoring this check in the old compilers
Reflection will be distributed in a separate jar and not in kotlin-runtime.jar
for two primary reasons:
- Reflection implementation at the moment takes almost 2Mb
- Separate libraries for separate features is a technique encouraged by Maven,
and it's inconvenient to make it different in the compiler distribution
ProGuard complains if we're trying to shrink compiler with the full runtime in
dependencies because for the compiler produced on the first step of bootstrap
these two jars contain conflicting classes. This won't matter in the final
distribution because we will strip 'core' modules from compiler.jar. But this
matters in the first step because core will be different in the compiler (used
to load compiled class files) and in the reflection (used to introspect symbols
at runtime).
kotlin-runtime-minimal.jar still contains the complete reflection API and some
stub implementations in module 'reflection.stub.jvm', but doesn't have core, so
it won't cause a proguard error
Ilya Gorbunov