That file is the compiler's list of reserved keywords, so some of them may not have been added to docs, or they're experimental/internal/...
I'm not 100% sure but I think the swift doc you linked is missing at least a dozen keywords so the truth probably lies in the middle
Ah makes sense, personally I wouldn't consider reserved but unused words as keywords in the sense that you don't need to know them to read the language (even though they're keywords in some other technical sense). I was curious because I just tried counting number of keywords by language and it seemed surprisingly ambiguous/subjective/up to the language to say what's a "keyword" vs some type of core module. So my attempt (https://correctarity.com/keywords) probably has mistakes...