[release/6.0] Set generic type arguments nullability for value types

[github-actions]

Backport of #58036 to release/6.0
Issue: #57920

/cc @buyaa-n

Customer Impact

Generic type parameters nullability not set for value types, which causes bug for generic parameters of ValueTuple. Customers would expect to have nullability info for generic parameters because it is not set for ValueTuple they would get a runtime exception

Testing

Unit/CI

Risk

Low, bug fix for broken 6.0 scenario

[danmoseley]

Nit (for later) typo: NullablNotNullIfNotNullReturn --> NullableNotNullIfNotNullReturn

[danmoseley]

Some of the test types/members in the test file here don't seem used:

MethodTupleNullNonNull
FieldMaybeNull2
PropertyDisabledAllowNull
PropertyDisabledMaybeNull
PropertyNullableEnabled
MethodEnumerableNonNonNullUnknownNullNonNullNon
MethodNullableDisabled

Do any of those suggest missing tests? If not they can be cleaned up in a future PR.

[danmoseley]

Approved for release/6.0. New API, significant bug, customer reported, localized fix.
Please double check for extra relevant tests we should add here though, to help catch any other bugs we might have to fix later.

[buyaa-n]

Do any of those suggest missing tests? If not they can be cleaned up in a future PR.

Good catch, some of them missing tests, some not needed, I will clean up with a different PR

[danmoseley]

We have some time, so would it make sense to add those missing tests, and roll them into this PR? In case they find something else.

[buyaa-n]

We have some time, so would it make sense to add those missing tests, and roll them into this PR? In case they find something else.

I don't expect they find something else, but sure its good to have

[buyaa-n]

In case they find something else.

I don't expect they find something else

You are right, it found something 👍, thanks! PR up

[danmoseley]

@buyaa-n this might not meet the bar >=Sept 14th. Is it nearly ready?

[buyaa-n]

@buyaa-n this might not meet the bar >=Sept 14th. Is it nearly ready?

Waiting for #58479 approval and merge, then I will cherry-pick that commit to this PR

[buyaa-n]

@buyaa-n this might not meet the bar >=Sept 14th. Is it nearly ready?

Waiting for #58479 approval and merge, then I will cherry-pick that commit to this PR

@danmoseley the updates pushed to this PR, it is now ready for review/merge

[danmoseley]

Approved. Fixing customer reported bug (and similar bugs) in feature that's new in 6.0. Risk of affecting unrelated code is low as we don't call through this API.

[danmoseley]

@buyaa-n can someone give this a signoff? then I can merge it.

[buyaa-n]

[buyaa-n]

@buyaa-n can someone give this a signoff? then I can merge it.

Probably it should not be my sing-off @stephentoub@steveharter@jeffhandley