feat(stackable-versioned): Generate From implementations for automatic versions upgrades

crates/stackable-versioned-macros/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "stackable-versioned-macros"
+version = "0.1.0"
+authors.workspace = true
+license.workspace = true
+edition.workspace = true
+repository.workspace = true
+
+[lib]
+proc-macro = true
+
+[dependencies]
+k8s-version = { path = "../k8s-version", features = ["darling"] }
+
+darling.workspace = true
+proc-macro2.workspace = true
+syn.workspace = true
+quote.workspace = true
+
+[dev-dependencies]
+rstest.workspace = true

crates/stackable-versioned/src/attrs/container.rs → crates/stackable-versioned-macros/src/attrs/container.rs

@@ -59,6 +59,10 @@ impl ContainerAttributes {
             }
         }
 
+        // TODO (@Techassi): Add validation for skip(from) for last version,
+        // which will skip nothing, because nothing is generated in the first
+        // place.
+
         // Ensure every version is unique and isn't declared multiple times. This
         // is inspired by the itertools all_unique function.
         let mut unique = HashSet::new();
@@ -83,10 +87,12 @@ impl ContainerAttributes {
 ///
 /// - `name` of the version, like `v1alpha1`.
 /// - `deprecated` flag to mark that version as deprecated.
+/// - `skip` option to skip generating various pieces of code.
 #[derive(Clone, Debug, FromMeta)]
 pub(crate) struct VersionAttributes {
     pub(crate) deprecated: Flag,
     pub(crate) name: Version,
+    pub(crate) skip: Option<SkipOptions>,
 }
 
 /// This struct contains supported container options.
@@ -95,7 +101,19 @@ pub(crate) struct VersionAttributes {
 ///
 /// - `allow_unsorted`, which allows declaring versions in unsorted order,
 ///   instead of enforcing ascending order.
+/// - `skip` option to skip generating various pieces of code.
 #[derive(Clone, Debug, Default, FromMeta)]
 pub(crate) struct ContainerOptions {
     pub(crate) allow_unsorted: Flag,
+    pub(crate) skip: Option<SkipOptions>,
+}
+
+/// This struct contains supported skip options.
+///
+/// Supported options are:
+///
+/// - `from` flag, which skips generating [`From`] implementations when provided.
+#[derive(Clone, Debug, Default, FromMeta)]
+pub(crate) struct SkipOptions {
+    pub(crate) from: Flag,
 }

crates/stackable-versioned/src/attrs/field.rs → crates/stackable-versioned-macros/src/attrs/field.rs

@@ -1,6 +1,7 @@
 use darling::{util::SpannedValue, Error, FromField, FromMeta};
 use k8s_version::Version;
-use syn::{Field, Ident};
+use proc_macro2::Span;
+use syn::{Field, Ident, Path};
 
 use crate::{attrs::container::ContainerAttributes, consts::DEPRECATED_PREFIX};
 
@@ -40,6 +41,16 @@ pub(crate) struct FieldAttributes {
 #[derive(Clone, Debug, FromMeta)]
 pub(crate) struct AddedAttributes {
     pub(crate) since: SpannedValue<Version>,
+
+    #[darling(rename = "default", default = "default_default_fn")]
+    pub(crate) default_fn: SpannedValue<Path>,
+}
+
+fn default_default_fn() -> SpannedValue<Path> {
+    SpannedValue::new(
+        syn::parse_str("std::default::Default::default").unwrap(),
+        Span::call_site(),
+    )
 }
 
 #[derive(Clone, Debug, FromMeta)]
@@ -139,6 +150,7 @@ impl FieldAttributes {
 
         // First, validate that the added version is less than the deprecated
         // version.
+        // NOTE (@Techassi): Is this already covered by the code below?
         if let (Some(added_version), Some(deprecated_version)) = (added_version, deprecated_version)
         {
             if added_version >= deprecated_version {