https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119751
--- Comment #8 from Zbigniew <zbigniew2011 at gmail dot com> --- I'd like also to note there's also a need to take better care about the docs; for example: I tried a code snippet from https://gcc.gnu.org/onlinedocs/gm2/Assembly-language.html („2.17 Interface to assembly language”) — simply by including that proc definition into that „coroutine example” module. Unfortunately, both examples generate error message instead of code: coex2.mod: Assembler messages: coex2.mod:22: Error: operand type mismatch for `movq' So either something isn't right with both examples — or there's a need to describe something MORE DETAILED WAY immediately on the very same page (if it was my mistake?); that's what the docs are for, anyway.