cfg_select: Support unbraced expressions #145233
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When operating on expressions, `cfg_select!` can now handle expressions without braces. (It still requires braces for other things, such as items.) Expand the test coverage and documentation accordingly.
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| /// Parses a `TokenTree` consisting either of `{ /* ... */ }` (and strip the braces) or an | ||
| /// expression followed by a comma (and strip the comma). |
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Question: do you know why cfg_select! required braces previously? Did this have any grammar ambiguity problems?
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When it was not a built-in macro, I think it was needed to handle expressions. Once it became a built-in macro, I think it was just simplicity of implementation.
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When operating on expressions,
cfg_select!can now handle expressionswithout braces. (It still requires braces for other things, such as
items.)
Expand the test coverage and documentation accordingly.
I'm not sure whether deciding to extend
cfg_select!in this way is T-lang or T-libs-api. I've labeled for both, with the request that both teams don't block on each other. :)