docs(gctx): move inline comment to doc comment for Value<T>

Author: weihanglo

src/cargo/util/context/value.rs

@@ -7,6 +7,24 @@
 //! debugging). The `Value<T>` type here can be used to deserialize a `T` value
 //! from configuration, but also record where it was deserialized from when it
 //! was read.
+//!
+//! Deserializing `Value<T>` is pretty special, and serde doesn't have built-in
+//! support for this operation. To implement this we extend serde's "data model"
+//! a bit. We configure deserialization of `Value<T>` to basically only work with
+//! our one deserializer using configuration.
+//!
+//! We define that `Value<T>` deserialization asks the deserializer for a very
+//! special struct name and struct field names. In doing so the deserializer will
+//! recognize this and synthesize a magical value for the `definition` field when
+//! we deserialize it. This protocol is how we're able to have a channel of
+//! information flowing from the configuration deserializer into the
+//! deserialization implementation here.
+//!
+//! You'll want to also check out the implementation of `ValueDeserializer` in
+//! `de.rs`. Also note that the names below are intended to be invalid Rust
+//! identifiers to avoid how they might conflict with other valid structures.
+//! Finally the `definition` field is transmitted as a tuple of i32/string, which
+//! is effectively a tagged union of `Definition` itself.
 
 use crate::util::context::GlobalContext;
 use serde::de;
@@ -29,24 +47,6 @@ pub struct Value<T> {
 
 pub type OptValue<T> = Option<Value<T>>;
 
-// Deserializing `Value<T>` is pretty special, and serde doesn't have built-in
-// support for this operation. To implement this we extend serde's "data model"
-// a bit. We configure deserialization of `Value<T>` to basically only work with
-// our one deserializer using configuration.
-//
-// We define that `Value<T>` deserialization asks the deserializer for a very
-// special struct name and struct field names. In doing so the deserializer will
-// recognize this and synthesize a magical value for the `definition` field when
-// we deserialize it. This protocol is how we're able to have a channel of
-// information flowing from the configuration deserializer into the
-// deserialization implementation here.
-//
-// You'll want to also check out the implementation of `ValueDeserializer` in
-// `de.rs`. Also note that the names below are intended to be invalid Rust
-// identifiers to avoid how they might conflict with other valid structures.
-// Finally the `definition` field is transmitted as a tuple of i32/string, which
-// is effectively a tagged union of `Definition` itself.
-
 pub(crate) const VALUE_FIELD: &str = "$__cargo_private_value";
 pub(crate) const DEFINITION_FIELD: &str = "$__cargo_private_definition";
 pub(crate) const NAME: &str = "$__cargo_private_Value";