this finally gives us a witness type we can use to prove that a certain
call graph subtree can't be used in kj promises using only a single new
assumption: if EvalState& is never held as a reference member of a type
and instead only ever passes as an argument or held on the stack we can
be certain that anything that has access to en EvalState ref must never
be run inside a promise and, crucially, that anything that doesn't have
access to an EvalState& *can* be run inside a promise without problems.
Change-Id: I6c15ada479175ad7e6cd3e4a729a5586b3ba30d6
for the same reason the eval caches should not keep them as references,
only worse: installables cannot fully lose their reference member since
some types of installable (flakes -sigh-) need access to caches held by
their member reference. passing that around as well at all times is not
feasible; passing in EvalState& all the time is quite bad enough as is.
Change-Id: I05d438623b5ef10fc22e7e256b89447e61a0657d
it's not used for anything any more. it was only passed on to the AttrDb
constructor, which itself only stashed it away to an unused member field
Change-Id: I334fde751a3754e6580f573c21ae3d04be00345a
and for the same reason DrvInfo shouldn't, only even more so. the eval
cache infrastructure wants to be a wrapper around evaluation, with its
lifetimes fully decoupled from the lifetime of the wrapped evaluation.
this can't not create problems when eval lifetime must become bounded.
Change-Id: Ib8eec649995b4decd7290c2266322f67d73b6b46
it's all strings anyway. the db stores strings, the cli wants to
interact with attr paths as strings, so we will just use strings
Change-Id: Id9ea07d92343de77e8d47af8fec1e86ae225e9a1
this will let us pass the capability to create debuggable eval errors
without having to pass an entire EvalState. we could pass symbols and
debug states around just as easily, but if we add new capabilities to
our debugger we might have to change many more places than with this.
Change-Id: I2f8893012e5d98a986ef1fc888234c2dd8d5e096
eval caches are not used by actual eval at all, only by the flake-shaped
wrappers around evaluation. moving caches into a subclass both clarifies
that eval caches and eval states are coupled and separates concerns that
should not have been intermixed as they were here. in the future we will
want to split up and decouple things even further. that'll have to wait.
Change-Id: I7b69510c0f8b212f05fae62e7b992d9475b4841f
not all of these are even used by eval itself. notably sWith wasn't used
at all, sEpsilon was only used by the eval cache one layer up, and other
attributes are used in places even further away from eval itself. we can
keep this commingling for now, but eventually we should clean it up too.
Change-Id: I5684ac614361bf008e04472130c6c02082b4c2d7
clangd broke because it can't look through symlinks. compile_commands
manipulation does not fix it, clangd configuration does not fix it, a
vfs overlay does not fix it, and while a combination of those can fix
it with a bind mount in place that's just too cursed to even consider
clangd bug: https://github.com/llvm/llvm-project/issues/116877
Change-Id: I8e3e8489548eb3a7aa65ac9d12a5ec8abf814aec
