the parser treats a plain \r as a newline, error reports do not. this
can lead to interesting divergences if anything makes use of this
feature, with error reports pointing to wrong locations in the input (or
even outside the input altogether).
(cherry picked from commit 2be6b143289e5479cc4a2667bb84e879116c2447)
Change-Id: Ieb7f7655bac8cb0cf5734c60bd41723388f2973c
Combine `AbstractPos`, `PosAdapter`, and `Pos`
(cherry picked from commit 113499d16fc87d53b73fb62fe6242154909756ed)
===
this is a bit cursed because originally it was based on InputAccessor
code that we don't have and moved/patched features we likewise don't
have (fetchToStore caching, all the individual accessors,
ContentAddressMethod). the commit is adjusted accordingly to
match (remove caching, ignore accessors, use FileIngestionMethod).
note that `state.rootPath . CanonPath == abs` and
computeStorePathForPath works relative to cwd, so the slight rewrite in
the moved fetchToStore is legal.
Change-Id: I05fd340c273f0bcc8ffabfebdc4a88b98083bce5
eldritch horrors