[theresistor]

The textual IR is not backwards compatible, but the bitcode format has been best-effort auto-upgradeable for as long as I've been involved (2006). The policy is documented here: https://llvm.org/docs/DeveloperPolicy.html#ir-backwards-comp...

[almostgotcaught]

bitcode policy i'm aware of - it's the "IR" part that caught my attention.

[mannycalavera42]

a pretty evident case of not almost got caught