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fix(ext/ffi): improve error messages in FFI module (#17786)
Fixes #16922. The error messages in the `ffi` module are somewhat cryptic when passing functions that have invalid `parameters` or `result` type strings. While the generated serializer for the `ForeignFunction` struct correctly outputs a correct and verbose message, the user sees a far less helpful `data did not match any variant` message instead. The underlying cause appears to be the fallback message in the auto-derived deserializer for untagged enums [1] generated as a result of `ForeignSymbol` being marked as `#[serde(untagged)]` [2]. Passing an unexpected value for `NativeType` causes it to error out while attempting to deserialize both enum variants -- once because it's not a match for the `ForeignStatic` variant, and once because the `ForeignFunction` deserializer rejects the invalid type for the parameters/return type. This is currently open as [serde #773](serde-rs/serde#773), and not a trivial exercise to fix generically. [1] https://github.com/serde-rs/serde/blob/v0.9.7/serde_derive/src/de.rs#L730 [2] https://github.com/denoland/deno/blob/main/ext/ffi/dlfcn.rs#L102 [3] serde-rs/serde#773 Note that the auto-generated deserializer for untagged enums uses a private API to buffer deserializer content that we don't have access to. Instead, we can make use of the `serde_value` crate to buffer the values. This can likely be removed once the official buffering API lands (see [4] and [5]). In addition, this crate pulls in `serde_json` as a cheap way to test that the deserializer works properly. [4] serde-rs/serde#741 [5] serde-rs/serde#2348
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