[release/6.0] Don't consider classes that do not have any attributes or base classes

[github-actions]

Backport of #57750 to release/6.0

/cc @eiriktsarpalis@chsienki

Customer Impact

This is a performance optimization intended to mitigate the issues reported in #56702: sluggish VS performance when editing solutions with a large number of classes.

Testing

Does not make any changes to functional behavior, the existing source gen test suite should suffice in catching any functional regressions.

Risk

Low. Applies a straightforward performance optimization to the ISyntaxReceiver implementation filtering out any syntax nodes that the source generator is explicitly not supporting.

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Issue Details

---

Backport of #57750 to release/6.0

/cc @eiriktsarpalis@chsienki

Customer Impact

Testing

Risk

Author:	github-actions[bot]
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[danmoseley]

there's no template, but approved. Risk seems low and we know we need to improve perf of the source generators to successfully ship.

I assume that a unit test isn't really feasible.

[danmoseley]

@ericstj@eiriktsarpalis we're likely already flowing another set of changes for RC1, any reason we shouldn't get this in there? That would presumably improve the perf data we get from customers using RC1.

[eiriktsarpalis]

there's no template, but approved.

Whoops, updated now.

we're likely already flowing another set of changes for RC1, any reason we shouldn't get this in there?

Decision was made to not backport this to RC1, since it only applies to the V1 implementation. cc @ericstj

[eiriktsarpalis]

@danmoseley this should be ready to merge.