# Description of Changes
This PR fixes a C# codegen performance/behavior issue triggered by views
that include nullable value-type fields (e.g. `DbVector2?`), as reported
in #3914.
* Updated the C# BSATN code generator to emit non-boxing equality for
`Nullable<T>` members by using `System.Nullable.Equals(a, b)` rather
than `a.Equals(b)` (which can box and cause excessive host logging/work
in view diff/equality paths).
This causes code generation to change from something like:
``` csharp
// From:
var ___eqNullableIntField = this.NullableIntField.Equals(that.NullableIntField);
// To:
var ___eqNullableIntField = System.Nullable.Equals(
this.NullableIntField,
that.NullableIntField
);
```
* Added a regression scenario to the C# regression-test module that
exercises the problematic pattern:
* A table containing a nullable struct field (`DbVector2? Pos`).
* A public view that returns rows containing that nullable field.
* A reducer to mutate the nullable field from `some` → `none` → `some`
to force view re-evaluation and diffing.
* Updated the regression-test client to:
* Subscribe to the new view.
* Validate that the view evaluates successfully and contains the
expected rows.
* Call the reducer and validate view state after updates.
* Fail the test if view evaluation/diffing produces errors.
# API and ABI breaking changes
None.
* No changes to public SpacetimeDB schema or wire format semantics.
* Changes are limited to generated equality code and regression tests.
# Expected complexity level and risk
2 - Low
* The codegen change is small and localized (special-casing
`System.Nullable<T>` equality generation).
* Risk is primarily around subtle behavior differences in equality for
nullable value types; however, `System.Nullable.Equals` matches the
expected semantics and avoids boxing.
* Regression tests specifically cover the nullable-struct-in-view
scenario to guard against regressions.
# Testing
<!-- Describe any testing you've done, and any testing you'd like your
reviewers to do,
so that you're confident that all the changes work as expected! -->
- [X] Ran the C# regression test suite via `run-regression-tests.sh` and
confirmed no errors.
# Description of Changes
Fixes
https://github.com/orgs/clockworklabs/projects/22?pane=issue&itemId=102392974&issue=clockworklabs%7Ccom.clockworklabs.spacetimedbsdk%7C276
by renaming `internal` `static` serializer fields so that they do not
overlap with user-provided names.
Note, however, that some field names still will not work: `ReadFields`,
`WriteFields`, `Equals`, and `GetHashCode`.
This would require a separate fix since the error would happen in a
different place. In this case we would need to change the name of the
generated member to something like `ReadFields_` or `Equals_`, which I'm
not sure is a good idea.
# API and ABI breaking changes
N/A
# Expected complexity level and risk
0
# Testing
SDK tests and `dotnet-verify` tests are passing.
---------
Signed-off-by: rekhoff <r.ekhoff@clockworklabs.io>
Co-authored-by: rekhoff <r.ekhoff@clockworklabs.io>
Ryan