Can you show some example(s) of those type instabilities in cases where they are actually relevant (not by design)?
I think type instabilities that are by design are still problematic. For one, they prevent static analysis of your program. Both by blocking inference and by spamming the JET output so you miss the real issues Eventually, they might also prevent compilation of your program to static binaries (but let’s see).
Some examples of this are:
- Spurious instabilities in Base. These tends to be quickly fixed. Examples include #49801 and #48420
- Instabilities intentionally added to curb compile times. These are typically in print- and show-related methods
- Instabilities in packages, due to design issues. This is rampant in Pkg, in Artifacts and in some packages like FilePathsBase.