[release/8.0] Fix Options Source Gen Trimming Issues

[github-actions]

Backport of #93088 to release/8.0

#92327

/cc @tarekgh

Customer Impact

Applications constructed with AOT compilation and employing the Options validation source generator may encounter warnings stemming from the generated code. This occurs due to the generation of code reliant on types adorned with the RequiredUnreferencedCode attribute. These types utilize reflection and are not conducive to AOT builds due to their lack of trim-friendliness.

Details

This change addresses issues that arise when using the Options source generator in AOT builds. The trimming linker generates warnings due to the use of Validation attributes that rely on reflection. Additionally, the source generator emits code that uses ValidationContext, which has constructors annotated with the RequiredUnreferencedCode attribute, leading to linker warnings. It's important to note that the ValidationContext object created in this context is exclusively used within the Validator.TryValidateValue API call.

The solution consists of two parts:

• We generate code to create the ValidationContext object and initialize the display and member names within it. This ensures the object's safe use because the reflection code path is not executed during this time. Consequently, we suppress the trimming linker warnings associated with this part.
• For attributes such as MaxLengthAttribute, MinLengthAttribute, LengthAttribute, CompareAttribute, and RangeAttribute, which rely on reflection, we generate replacement attributes. These replacement attributes are strongly typed and entirely avoid the use of reflection.

These changes address the issues and improve the overall safety and performance of the code in AOT buildings.

Testing

I conducted a manual test of the relevant scenario and successfully passed all regression tests. Additionally, I included more tests to encompass the specific areas we are addressing.

Risk

These modifications are limited in scope to the five validation attributes that are not trim-friendly. We have not made any alterations to the source generator's other logic.

IMPORTANT: If this backport is for a servicing release, please verify that:

• The PR target branch is release/X.0-staging, not release/X.0.

• If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.

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Tagging subscribers to this area: @dotnet/area-meta
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Issue Details

---

Backport of #93088 to release/8.0

/cc @tarekgh

Customer Impact

Testing

Risk

IMPORTANT: If this backport is for a servicing release, please verify that:

• The PR target branch is release/X.0-staging, not release/X.0.

• If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.

Author:	github-actions[bot]
Assignees:	-
Labels:	area-Meta
Milestone:	-

[ghost]

Tagging subscribers to this area: @dotnet/area-extensions-options
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Backport of #93088 to release/8.0

#92327

/cc @tarekgh

Customer Impact

Applications constructed with AOT compilation and employing the Options validation source generator may encounter warnings stemming from the generated code. This occurs due to the generation of code reliant on types adorned with the RequiredUnreferencedCode attribute. These types utilize reflection and are not conducive to AOT builds due to their lack of trim-friendliness. Here are some more details:

This change addresses issues that arise when using the Options source generator in AOT builds. The trimming linker generates warnings due to the use of Validation attributes that rely on reflection. Additionally, the source generator emits code that uses ValidationContext, which has constructors annotated with the RequiredUnreferencedCode attribute, leading to linker warnings. It's important to note that the ValidationContext object created in this context is exclusively used within the Validator.TryValidateValue API call.

The solution consists of two parts:

• We generate code to create the ValidationContext object and initialize the display and member names within it. This ensures the object's safe use because the reflection code path is not executed during this time. Consequently, we suppress the trimming linker warnings associated with this part.
• For attributes such as MaxLengthAttribute, MinLengthAttribute, LengthAttribute, CompareAttribute, and RangeAttribute, which rely on reflection, we generate replacement attributes. These replacement attributes are strongly typed and entirely avoid the use of reflection.

These changes address the issues and improve the overall safety and performance of the code in AOT buildings.

Testing

I conducted a manual test of the relevant scenario and successfully passed all regression tests. Additionally, I included more tests to encompass the specific areas we are addressing.

Risk

These modifications are limited in scope to the five validation attributes that are not trim-friendly. We have not made any alterations to the source generator's other logic.

IMPORTANT: If this backport is for a servicing release, please verify that:

• The PR target branch is release/X.0-staging, not release/X.0.

• If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.

Author:	github-actions[bot]
Assignees:	-
Labels:	Servicing-consider, area-Extensions-Options
Milestone:	-

[tarekgh]

CC @jeffhandley @eiriktsarpalis @ericstj

[ericstj]

Test failure here looks related:

  Starting:    Microsoft.Extensions.Options.SourceGeneration.Tests (parallel test collections = on, max threads = 2)
    Microsoft.Gen.OptionsValidation.Test.EmitterTests.TestEmitter [FAIL]
      Assert.Equal() Failure
                                       ↓ (pos 128490)
      Expected: ··· class __SourceGen__MinLengthAttribute : global::System.Compo···
      Actual:   ··· class __SourceGen__RangeAttribute : global::System.Component···
                                       ↑ (pos 128490)
      Stack Trace:
        /_/src/libraries/Microsoft.Extensions.Options/tests/SourceGenerationTests/EmitterTests.cs(56,0): at Microsoft.Gen.OptionsValidation.Test.EmitterTests.TestEmitter()
        --- End of stack trace from previous location ---

[tarekgh]

Test failure here looks related:

Yes, I am looking at that.

[ericstj]

LGTM, thank you for fixing the failing test

[carlossanlop]

CI failures are unrelated: #91757 #93250