Macro called in pattern-without-range expand to a _single_ pattern #494
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Signed-off-by: Sasha Pourcelot <[email protected]>
scrabsha
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May 5, 2024
Part of #29. Things that are missing: - Qualified paths in patterns (we don't support them at all) - Macro calls. Support for `#[expandable::pat]` has also been added. I found a cool side-quest while working on this: ferrocene/specification#494. --------- Signed-off-by: Sasha Pourcelot <[email protected]>
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Thanks! @Veykril could you take a look at this? |
Veykril
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May 16, 2024
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Nice catch, thanks! |
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The current specification says that a macro called in pattern context can expand to zero or more patterns.
I believe this is incorrect, as e.g.
0 1 _is effectively 0 or more patterns, but is not a valid expansion (playground link). Similarly, expanding to 0 patterns is invalid (playground link).As I understand it, the intent was to state that e.g.
0 | 1 | _is a valid expansion for a pattern called in pattern context. As such, I changed the wording so that macro calls in pattern context must expand to a pattern, which matches0 | 1 | _and makes "expanding to zero patterns" invalid.