Explicitly convert assignable nil interface values #49
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The reflect package has a bug (golang/go#22143). Let R and T both be interface types and R be assignable to T. Let F be a function that takes T as its argument. Go language lets you directly call F with a nil T or a nil R (since R is assignable to T) without any special handling. Currently, reflect allows you to call F with a nil T, but panics when F with a nil R. To avoid this panic, we explicitly check for the condition where a value: * is an interface type * is nil * is not exactly same as type T and re-create the value as a nil interface of type T.
Fun observation, the GopherJS implementation of |
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The reflect package has a bug (golang/go#22143).
Let R and T both be interface types and R be assignable to T.
Let F be a function that takes T as its argument.
The Go language lets you directly call F with a nil T or a nil R
(since R is assignable to T) without any special handling.
Currently, reflect allows you to call F with a nil T,
but panics when calling F with a nil R. To avoid this panic,
we explicitly check for the condition where a value:
* is an interface type
* is nil
* is not exactly same as type T
and re-create the value as a nil interface of type T.