[PATCH] D95561: [Clang] Introduce Swift async calling convention.

[John McCall via Phabricator via llvm-commits]

rjmccall added inline comments.


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Comment at: clang/include/clang/Basic/AttrDocs.td:4409
+  calls to other ``swiftasynccall`` functions must be in tail position
+  (in all language modes). In particular:
+  - For C, this implies that ``return async_f();`` (``async_f`` is another
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I don't think the "must be in tail position" here is true.  Allow me to suggest an alternative way of saying this:

> Within a `swiftasynccall` function, a call to a `swiftasynccall` function that is the immediate operand of a `return` statement is guaranteed to be performed as a tail call.  This syntax is allowed even in C as an extension (a call to a `void`-returning function cannot be a `return` operand in standard C).  If something in the calling function would semantically be performed after a guaranteed tail call, such as the non-trivial destruction of a local variable or temporary, then the program is ill-formed.


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https://reviews.llvm.org/D95561