The first commit reverts the revert of #23787.
The second fixes lambdalifting in convolutedly nested
closures/closureiters. This is considered to be the reason of #24094,
though I can't tell for sure, as I was not able to reproduce #24094 for
complicated but irrelevant reasons. Therefore I ask @jmgomez, @metagn or
anyone who could reproduce it to try it again with this PR.
I would suggest this PR to not be squashed if possible, as the history
is already messy enough.
Some theory behind the lambdalifting fix:
- A closureiter that captures anything outside its body will always have
`:up` in its env. This property is now used as a trigger to lift any
proc that captures such a closureiter.
- Instantiating a closureiter involves filling out its `:up`, which was
previously done incorrectly. The fixed algorithm is to use "current" env
if it is the owner of the iter declaration, or traverse through `:up`s
of env param until the common ancestor is found.
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
refs #24094, soft reverts #23787#23787 turned out to cause issues as described in #24094, but the
changes are still positive, so it is now only enabled if compiling with
`-d:nimOptIters`. Unfortunately the changes are really interwoven with
each other so the checks for this switch in the code are a bit messy,
but searching for `nimOptIters` should give the necessary clues to
remove the switch properly later on.
Locally tested that nimlangserver works but others can also check.
This pr redefines the relation between lambda lifting and closureiter
transformation.
Key takeaways:
- Lambdalifting now has less distinction between closureiters and
regular closures. Namely instead of lifting _all_ closureiter variables,
it lifts only those variables it would also lift for simple closure,
i.e. those not owned by the closure.
- It is now closureiter transformation's responsibility to lift all the
locals that need lifting and are not lifted by lambdalifting. So now we
lift only those locals that appear in more than one state. The rest
remains on stack, yay!
- Closureiter transformation always relies on the closure env param
created by lambdalifting. Special care taken to make lambdalifting
create it even in cases when it's "too early" to lift.
- Environments created by lambdalifting will contain `:state` only for
closureiters, whereas previously any closure env contained it.
IMO this is a more reasonable approach as it simplifies not only
lambdalifting, but transf too (e.g. freshVarsForClosureIters is now gone
for good).
I tried to organize the changes logically by commits, so it might be
easier to review this on per commit basis.
Some ugliness:
- Adding lifting to closureiters transformation I had to repeat this
matching of `return result = value` node. I tried to understand why it
is needed, but that was just another rabbit hole, so I left it for
another time. @Araq your input is welcome.
- In the last commit I've reused currently undocumented `liftLocals`
pragma for symbols so that closureiter transformation will forcefully
lift those even if they don't require lifting otherwise. This is needed
for [yasync](https://github.com/yglukhov/yasync) or else it will be very
sad.
Overall I'm quite happy with the results, I'm seeing some noticeable
code size reductions in my projects. Heavy closureiter/async users,
please give it a go.
* fixes#21043; fixes a named exception in the infixAs expression which generate an implicit uninitialized let statement
* Update compiler/sempass2.nim
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
* silence error output from template_various.nim
* any => auto in tests
* avoid showing failed for parseSpec since this is expected behavior in 2 cases: tincludefile.nim, tnav1.nim
* enforce InheritFromException
* fixup
* config update
* disable a questionable test
* remove c++ exception handling IDs, new impl doesn't require it anymore
* C++ based exceptions finally work
* fixes bootstrapping problem in C++ mode
* teach GCC it's 2020 now
* more bugfixes for C++ based exception handling
* apply cooldome's patch
* another attempt to enable C++11
* bug fix
Co-authored-by: Araq <rumpf_a@web.de>
Co-authored-by: cooldome <ariabushenko@bk.ru>
