Encountered in realistic scenario. Didn't really look at this one. AI
one shot it lol
When a module defines method-bearing types and a when isMainModule
block imports additional modules that also define methods on the same
type hierarchy, sortVTableDispatchers crashes with:
Error: unhandled exception: key not found: (module: N, item: M)
[KeyError]
Root cause: the itemTable built during vtable sorting is populated
from g.objectTree[baseType], which only contains types from the
current compilation pass. When when isMainModule triggers re-import
of method-bearing modules, the method bucket contains types from both
passes. Types from the first pass have ItemIds not present in the
second pass's object tree, so itemTable[obj.itemId] raises KeyError
at line 155.
Fix: if obj.itemId is missing from itemTable, create an empty slot
array of the correct length. The entry is a local temporary — the
second loop in sortVTableDispatchers only calls setMethodsPerType
for types in the current object tree, so types from the prior pass
retain their already-established dispatch. The entry exists solely to
prevent the KeyError during the assignment loop.
The methodIndexLen used for the new entry is the bucket's slot count,
which is correct for any type in the hierarchy.
Added test tests/method/tvtable_reentry.nim that defines methods
across three types in two compilation passes and verifies dispatch
correctness for all three.
**TODO**
- [x] fixes changelog
With the new option `nimPreviewVtables`, `methods` are confined in the
same module where the type of the first parameter is defined
- [x] make it opt in after CI checks its feasibility
## In the following-up PRs
- [ ] in the following PRs, refactor code into a more efficient one
- [ ] cpp needs special treatments since it cannot embed array in light
of the preceding limits: ref
https://github.com/nim-lang/Nim/pull/20977#discussion_r1035528927; we
can support cpp backends with vtable implementations later on the
comprise that uses indirect vtable access
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
* remove deprecated pragma syntax from 0.20.0
closes#4651, closes#16653 with a cheap fix for now due to
how early `tfFinal` is set
* remove type pragma between name and generics
* undo removal, try removing bind expression (0.8.14)
* fix test, unremove bind expr
* remove again
* Update changelog.md
Co-authored-by: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
* dependencies @ HEAD & weave test dependencies
* try fix package ci
Co-authored-by: konsumlamm <44230978+konsumlamm@users.noreply.github.com>
* Error -> Defect for defects
The distinction between Error and Defect is subjective,
context-dependent and somewhat arbitrary, so when looking at an
exception, it's hard to guess what it is - this happens often when
looking at a `raises` list _without_ opening the corresponding
definition and digging through layers of inheritance.
With the help of a little consistency in naming, it's at least possible
to start disentangling the two error types and the standard lib can set
a good example here.
When method prototypes were involved (e.g. forward declarations
for mutual recursion), calls were sometimes dispatched to the
wrong method implementation. One of the reasons was that method
dispatchers were then not always attached to method ASTs in
the correct place.
