Fix generate method type parameter nullability #39079
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Fixes dotnet#39074. Further commits will follow up on this one that futher refines various senarios.
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| // Add a ? if the type parameter is annotated as nullable, and the constraints allow it. It's possible to end up with | ||
| // a T? where T is constrained to class? if we combined a type parameter with some flow state -- we'll ignore the ? here | ||
| // at this stage. We should consider moving that check earlier when we actually wrap the symbol. |
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I recognize this check isn't right -- I'm just getting things off the ground to see what else might be breaking here.
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Can you elaborate when this would be incorrect? Is it the case where flow state shows that we don't need to mark as nullable only because null will never be passed in?
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The check for "HasReferenceTypeConstraint" is probably insufficient, because you can be constrainted to reference types if you have something like "T : SomeClass". And there's probably other cases too.
jasonmalinowski
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Can you include me when this is ready for review? Thanks! |
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@CyrusNajmabadi Sure! And to give some context: @333fred, @AlekseyTs and I are working through some of the details of eliminating the symbol wrapping and moving that to the compiler directly; this came out of that so this is somewhat bugfixing and somewhat exploratory. |
Sounds awesome! You guys rock! |
| [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsGenerateMethod)] | ||
| public async Task TestInvocationWithClassConstrainedTypeArgumentAndNullableTypes() | ||
| { | ||
| await TestInRegularAndScriptAsync( |
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Can we make sure to test nullable constraint with not-null flow analysis?
class C
{
public T M<T>() where T : class?, new
{
var t = new T();
return [|M2|](t);
}
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Isn't that the TestInvocationWithNullableClassConstrainedTypeArgumentAndNullableTypes test below?
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Based on current draft it looks good. Not complete, but does solve some immediate issues without regression afaict |
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