This PR introduces the `backward.privateInPublic` option to aid in
porting projects to the module system by temporarily allowing access to
private declarations from the public scope, even across modules. A
warning will be generated by such accesses unless
`backward.privateInPublic.warn` is disabled.
This PR removes uses of `Lean.RBMap` in Lean itself.
Furthermore some massaging of the import graph is done in order to avoid
having `Std.Data.TreeMap.AdditionalOperations` (which is quite
expensive) be the critical path for a large chunk of Lean. In particular
we can build `Lean.Meta.Simp` and `Lean.Meta.Grind` without it thanks to
these changes.
We did previously not conduct this change as `Std.TreeMap` was not
outperforming `Lean.RBMap` yet, however this has changed with the new
code generator.
@Kha The default value (false) for `pp.inaccessibleNames == false` help when
visualizing error messages (see test
`hidingInaccessibleNames.lean`). We added this feature after to hide
intermediate variables created by `match_syntax`.
However, this default value confused me in tactic mode. For example,
it will hide a hypotheses `x : Fin 0` if nobody depends on it, but as
a user we want to know we have it since we can close the goal using
it. Thus, I added `withPPInaccessibleNames act`, it executes `act`
using `pp.inaccessibleNames true` if the user did not explicitly set
it. I use this combinator at `FileWorker` and when producing the
`unsolved goals` error message. In all other scenarios, I believe
hiding these inaccessible variables is a good thing.
@Kha I was tired of writing `arbitrary _` :)
There 0 places in the stdlib where the type needs to be provided.
If in the future we need to specify the type we can use
`arbitrary (α := <type>)`
@Kha: the new `ST` (and `EST`) are escapable like the Haskell ST monad.
It makes `StateRefT` much more useful because we can now run it from pure
code.
