Linq: Adds support constant evaluation of Nullable<T>.HasValue

[ccurrens]

Description

This commit adds support for evaluating Nullable<T>.HasValue when the original nullable constant's HasValue is false.

Nullable<T> is tricky to use with reflection because of it's special runtime behavior. This manually determines if HasValue was false, and in that case returns a constant expression of false.

More details are in #3272.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Closing issues

closes #3272

[ealsur]

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[ealsur]

@khdang Please take a look

[FabianMeiswinkel]

LGTM - Thanks!

[ealsur]

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[ealsur]

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[ealsur]

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[ealsur]

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[ealsur]

@ccurrens It looks like the last commit is failing on the LinqTranslationBaselineTests.TestMemberAccess I'll try rerunning everything, but the error is:

Expected: ><![CDATA[SELECTVALUErootFROMrootWHERE(root["NumericField"]=4)]]></SqlQuery></Output></Result><Resul,
Actual:   ><![CDATA[]]></SqlQuery><ErrorMessage><![CDATA[Objectreferencenotsettoaninstanceofanobject.]]></Erro,
OutputPath: BaselineTest\TestOutput\LinqTranslationBaselineTests.TestMemberAccess.xml,
BaselinePath: BaselineTest\TestBaseline\LinqTranslationBaselineTests.TestMemberAccess.xml

[ealsur]

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[ccurrens]

@ccurrens It looks like the last commit is failing on the LinqTranslationBaselineTests.TestMemberAccess I'll try rerunning everything, but the error is:

Expected: ><![CDATA[SELECTVALUErootFROMrootWHERE(root["NumericField"]=4)]]></SqlQuery></Output></Result><Resul,
Actual:   ><![CDATA[]]></SqlQuery><ErrorMessage><![CDATA[Objectreferencenotsettoaninstanceofanobject.]]></Erro,
OutputPath: BaselineTest\TestOutput\LinqTranslationBaselineTests.TestMemberAccess.xml,
BaselinePath: BaselineTest\TestBaseline\LinqTranslationBaselineTests.TestMemberAccess.xml

Thanks for the heads up. I messed up the conversion of the first pattern expression back to what it needed to be. I'll post up the fix in just a minute.

targetConstant is { Value: null } was doing a null check on targetConstant and on targetConstant.Value. I only did the latter.

[ccurrens]

The property pattern for targetConstant is { Value: null } and the new check targetConstant != null && targetConstant.Value == null produce the same assembly (under x64 ryuJit at least), but I've leave it as discrete checks instead of the pattern match. Seemed safer since I don't know about other architectures.

[ealsur]

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[ealsur]

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[ealsur]

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