The detection of special cases of interpreter functions and interfaces
is more precise. It allows at least to complete parsing of
code where type is derived from a type assertion expression.
Fixes#770.
* fix: copy the type in recursion
In more advanced recursive cases, setting the rtype to interface may interfear with typeing. To stop this from happening, instead of setting t.val.rtype to interface in the hope it will be set correctly later, a copy if the type is made, and the rtype of the copy is set to interface{}.
* fix: detect intermediate recursive structs
In the case of a nested recussion, each symbol can have
a different perspective on the recursion. In this case,
it is impossible to move from one struct to the next.
To keep the perspectives the same, any intermediate struct
that contains a recursion should also be set to interface{}.
so that all perspectives are the same.
* fix: handle arb recursion
* chore: refactor dref to be consistent
* fix: invalid recursive struct issue
* fix: handle checkptr issue
* fix: move unsafe into function to stop ptr check
* fix: handle deref in assign
* fix: make interpreter methods discoverable by runtime
When generating an interface wrapper, lookup existing wrappers by method
to get the one with the biggest set of methods implemented by interpreter.
A string method is also added to wrappers, in order to provide a string
representation of the interpreter value rather than the wrapper itself
(at least for %s and %v verbs).
This allows the runtime to pickup an interpreter method automatically
even if the conversion to the interface is not specified in the script. As
in Go spec, it is enough for the type to implement the required methods.
A current limitation is that only single wrappers can be instantiated,
not allowing to compose interfaces.
This limitation can be removed when the Go reflect issue
https://github.com/golang/go/issues/15924 is fixed.
Fixes#435.
* test: add a simpler test
* fix: finish support of type assertions which was incomplete
TypeAssert was optimistically returning ok without verifying that
value could be converted to the required interface (in case of
type assert of an interface type), or not checking the type in
all conditions. There is now a working implements method for itype.
Fixes#640.
* style: appease lint
* fix: remove useless code block
* doc: improve comments
* avoid test conflict
