Add support for using alias = any_type.
#50167
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Tagging @agocke @333fred . Here's my approach for dotnet/csharplang#4284. It allows us to fit this capability into our existing syntax model. It's also an extremely tiny change for the compiler. The cost is mostly just in testing, and likely reducing some IDE assumptions about what teh RHS is for a using-alias. |
| @@ -215,6 +215,8 @@ internal enum MessageID | |||
| IDS_Return = MessageBase + 12790, | |||
| IDS_FeatureVarianceSafetyForStaticInterfaceMembers = MessageBase + 12791, | |||
| IDS_FeatureConstantInterpolatedStrings = MessageBase + 12792, | |||
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| IDS_FeatureUsingTypeAlias = MessageBase + 12800, | |||
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not sure hte number to pick here. i could make this 12793 if that's appropriate.
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This number is fine. It may need to be adjusted when merging to main, but likely there won't be a conflict.
| if (name.IsMissing && this.PeekToken(1).Kind == SyntaxKind.SemicolonToken) | ||
| type = alias == null ? this.ParseQualifiedName() : this.ParseType(); | ||
| if (type is not NameSyntax) | ||
| type = CheckFeatureAvailability(type, MessageID.IDS_FeatureUsingTypeAlias); |
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note: we could ParseType universally, but then give a specific error if it's not a named type for normal using directives. However, the upside of this appraoch is that someone can always assume if they have a normal using directive or using static directive that there is a name.
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CyrusNajmabadi
changed the title
using alias = type to the language.using alias = type to the language.
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@jaredpar do you know what the next steps woudl be here? |
Mostly at this point its' waiting a bit. From a design stand point there are still some issues to tackle on this feature. From a resource stand point we are over booked at the moment. In addition to the feature we've committed to delivering in C# 10 we've recently picked up some C# IDE work that is causing us to potentially shift other work into post C# 10. This feature is looking more likely for C# 11 at this point. Once we get out from under some of our existing commitments we can come back to this and look to getting it reviewed and put into a feature branch. |
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@cston anything else you'd like? |
src/Compilers/CSharp/Test/Syntax/Parsing/UsingDirectiveParsingTests.cs
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src/Compilers/CSharp/Test/Syntax/Parsing/TopLevelStatementsParsingTests.cs
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src/Compilers/CSharp/Test/Syntax/Parsing/UsingDirectiveParsingTests.cs
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@cston all feedback responded to. |
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:) |
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Thanks! 🧙 😄 |
Relates to championed proposal dotnet/csharplang#4284
Relates to spec https://github.com/dotnet/csharplang/blob/main/proposals/using-alias-types.md
Relates to test plan #56323