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Avoid casting Enumerable.Empty to IList #3836

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Merged
merged 1 commit into from
Oct 5, 2018
Merged

Avoid casting Enumerable.Empty to IList #3836

merged 1 commit into from
Oct 5, 2018

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@kacollins
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Fixes #3834.

rainersigwald
rainersigwald requested changes Oct 5, 2018
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Looks great! One nit, and I'm auditing the other uses of Enumerable.Empty<T> in our codebase to see if anything else looks fishy.

src/Build/Definition/ProjectCollection.cs
_loadedProjects.TryGetValue(fullPath, out List<Project> candidates);

return candidates ?? (IList<Project>)Enumerable.Empty<Project>();
return candidates ?? (IList<Project>)Array.Empty<Project>();
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Can you also remove the now-unnecessary cast?

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@kacollins kacollins Oct 5, 2018 •
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No, because candidates is a List<Project>. I get this error: Operator '??' cannot be applied to operands of type 'List<Project>' and 'Project[]'

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Ah, makes sense. My toy test project didn't use ??.

@rainersigwald rainersigwald changed the title Change return value for no matching projects from Enumerable to Array. Avoid casting Enumerable.Empty to IList Oct 5, 2018
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The bad assumption (that Enumerable.Empty<T> is an IList<T>) went in with #3819, and was valid until dotnet/corefx#31025 changed the concrete return type.

rainersigwald
rainersigwald approved these changes Oct 5, 2018
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Thanks!

AndyGerlicher
AndyGerlicher approved these changes Oct 5, 2018
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Looks good, thanks!

@rainersigwald rainersigwald merged commit 900ef36 into dotnet:vs15.9 Oct 5, 2018
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@rainersigwald rainersigwald rainersigwald approved these changes

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@AndyGerlicher AndyGerlicher AndyGerlicher approved these changes

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@kacollins @rainersigwald @AndyGerlicher