Compiler plugins can add new source roots to the next compilation round
by using `AnalysisResult.RetryWithAdditionalRoots`. Some plugins added
already existing source roots to this list in some cases. For example,
this is reproducible with `square/anvil` with incremental compilation
(KT-45100, KT-44925). Psi2ir didn't deduplicate the source files before,
which resulted in several classes with the same name linked to the same
symbol. This led to a "symbol is already bound" exception, and in case
of KT-44925, to an additional NPE when we were rendering the class to
display it in the message.
The solution is to deduplicate classes before psi2ir. Note that this
commit has two changes, in CLI and in psi2ir. Any one of these is
sufficient for fixing the problem, however both are made just to make it
more future-proof against new components and/or changes in existing
subsystems (e.g. fir2ir).
In the old JVM backend, similar deduplication was happening in
`ClassFileFactory.registerSourceFiles`, which is why the problem is not
reproducible there.
#KT-45100 Fixed
Alexander Udalov
83a4b6396a