defer, %defer, and ?defer #110
Description
-
defer expr, evaluates expr when control flow leaves scope -
%defer expr, evaluates expr when control flow leaves scope by returning an error from the function -
?defer expr, evaluates expr when control flow leaves scope by returning null from the function - defer valid at statement level only in parser
- error when there is a defer with 0 block exit paths
- make the returns respect defer
- error when there is a
%returnin a function with void return type - optimization where the node remembers if it was error wrapped from a payload, if that is returned, then we know it is not an error. when
%returnreturns it is for sure an error. otherwise we have to do a runtime check to find out if it's an error and then do the defer expression - better defer implementation - instead of duplicating the code at every exit path, make a basic block that exit paths point to.
- error for control flow inside an expression exiting the defer expression scope? for example you probably shouldn't be able to
returnin a defer.