[Macros] Allow keywords after # in freestanding macro expansions
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Allow keywords after `#` in freestanding macro expansions There is no reason why we shouldn’t allow keywords here. I also thought about allowing keywords after `@` but things become tricky here for two reasons: - In the parser, we parse a type after the `@`, which could start with a keyword itself (e.g. `any`). If we want to keep the parser logic to parse a type after `@` (which I think we should), then it becomes unclear what `@any T` should parse as. - We allow a space between `@` and the type name. This makes it very hard for recovery to tell whether `@ struct` refers to an attribute with name `struct` or if the user forgot to write the attribute name after `@`. Since almost all keywords are lowercase and attached member macros are usually spelled with an uppercase name, there are a lot fewer chances for clashes here, so I don’t think it’s worth allowing keywords after `@`. swiftlang#66444 rdar://110472060
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See swiftlang/swift-syntax#1778
Allow keywords after
#in freestanding macro expansionsThere is no reason why we shouldn’t allow keywords here.
I also thought about allowing keywords after
@but things become tricky here for two reasons:@, which could start with a keyword itself (e.g.any). If we want to keep the parser logic to parse a type after@(which I think we should), then it becomes unclear what@any Tshould parse as.@and the type name. This makes it very hard for recovery to tell whether@ structrefers to an attribute with namestructor if the user forgot to write the attribute name after@.Since almost all keywords are lowercase and attached member macros are usually spelled with an uppercase name, there are a lot fewer chances for clashes here, so I don’t think it’s worth allowing keywords after
@.#66444
rdar://110472060