Change trivia attribution rule to make comments trailing trivia unless separated by a newline #985
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…s separated by a newline This changes the trivia attribution rule in the new parser to consider all trivia up to the next newline as trailing trivia. Previously, comments were always considered trailing trivia. This was discussed last year in https://forums.swift.org/t/changing-comment-trivia-attribution-from-trailing-trivia-to-leading-trivia/50773. My idea is that right now is probably one of the best times to change this because switching from the old to the new parser is an active source change for all clients. Resolves rdar://68234477 Resolves rdar://95639215 Fixes swiftlang#438
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CodaFi
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We met to discuss the implications of this change and settled on accepting it. The forum thread contains a number of oddities that these rules still don't quite handle as well as one would hope, but the balance between "smarter" trivia attribution and an efficient trivia lexing scheme struck by this solution is better than the status quo in enough places that it's worth it.
This is also a behavior change that swiftlint and swift-format may have to adapt to.
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As of swiftlang/swift-syntax#985, the parser treats all trivia following a token up to the next line break as trailing trivia, including comments. This is a change from the former logic, which treated such comments as leading trivia of the following token. A great deal of the logic in swift-format was written in terms of that behavior, and attempts to rewrite it to use the new behavior instead have been difficult to get right in all cases. In the interest of expediency, I'm merging this workaround that shifts the trivia around to restore the old tree that we expected. This shouldn't be considered a long-term fix; we should eventually fix the misbehavior with the new layout and drop the extra mutation.
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This has changes to how comments are associated to nodes. See swiftlang/swift-syntax#985
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This has changes to how comments are associated to nodes. See swiftlang/swift-syntax#985
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This changes the trivia attribution rule in the new parser to consider all trivia up to the next newline as trailing trivia. Previously, comments were always considered trailing trivia.
This was discussed last year in https://forums.swift.org/t/changing-comment-trivia-attribution-from-trailing-trivia-to-leading-trivia/50773.
My idea is that right now is probably one of the best times to change this because switching from the old to the new parser is an active source change for all clients.
Resolves rdar://68234477
Resolves rdar://95639215
Fixes #438
CC @allevato @jpsim