apple
`os()` platform condition incorrectly defined in prose and language grammar
Location
https://github.com/swiftlang/swift-book/blob/d29368733ef0b2852c711a772b383cbfbb9b4740/TSPL.docc/ReferenceManual/Statements.md?plain=1#L1007 https://github.com/swiftlang/swift-book/blob/d29368733ef0b2852c711a772b383cbfbb9b4740/TSPL.docc/ReferenceManual/SummaryOfTheGrammar.md?plain=1#L701
Description
The lists of valid OS names used with os() are incomplete, as the language supports a variety of other OS names such as WASI and FreeBSD.
Correction
We should either leave the list open-ended, or try to comprehensively list everything the compiler supports.
It's also worth noting that if a developer passes some unsupported OS name, it's not a compiler error—the compiler will accept it, emit a warning, and just ignore the code as if it said false instead of os(whatever). So perhaps the grammar should reflect that, if possible.
TSPL documents only the platforms that have official support. If some are missing, yes we should add them.
For additional discussion, please see https://github.com/swiftlang/swift-book/pull/225 and https://github.com/swiftlang/swift-book/issues/245.
The grammar of the language allows for additional values even if they're not actually supported.
It would be sufficient to adjust the formal grammar to allow for any identifier token, with a comment to the effect of "these are the supported values; other values will compile but produce diagnostics".