When a field should be skipped during deserialization, it will not use its own Default implementation
when the container structure has `#[serde(default)]` set.
The serde_test Serializer and Deserializer panic in is_human_readable unless the
readableness has been set explicitly through one of the hidden functions. This
is to force types that have distinct readable/compact representations to be
tested explicitly in one or the other, rather than with a plain assert_tokens
which arbitrarily picks one.
We need to follow up by designing a better API in serde_test to expose this
publicly. For now serde_test cannot be used to test types that rely on
is_human_readable. (The hidden functions are meant for our test suite only.)
During serialization, internally tagged enums invoke the Serializer's
serialize_struct. In JSON this turns into a map which uses visit_map
when deserialized. But some formats employ visit_seq when
deserializing a struct. One example is rmp-serde. Such formats were
previously unable to deserialize an internally tagged enum. This
change fixes it by adding visit_seq for internally tagged enums.
Since we know exactly how many bytes we should serialize as we can hint
to the serializer that it is not required which further reduces the
serialized size when compared to just serializing as bytes.
This implements the KISS suggested in https://github.com/serde-rs/serde/issues/790.
It is possible that one of the other approaches may be better but this
seemed like the simplest one to reignite som discussion.
Personally I find the original suggestion of adding two traits perhaps slightly
cleaner in theory but I think it ends up more complicated in the end
since the added traits also need to be duplicated to to the `Seed`
traits.
Closes#790
As discussed in #1013, serialize_with functions attached to variants receive an
argument for each inner value contained within the variant. Internally such a
function is wired up to the serializer as if the variant were a newtype variant.
