Upgrade to magic_migrate proc macro interface

Cargo.toml

@@ -2,6 +2,9 @@
 resolver = "2"
 members = ["buildpacks/ruby", "commons"]
 
+[workspace.dependencies]
+cache_diff = { version = "1.1", features = ["bullet_stream"] }
+
 [workspace.package]
 edition = "2021"
 rust-version = "1.82"

buildpacks/ruby/Cargo.toml

@@ -30,7 +30,7 @@ ureq = { version = "2", default-features = false, features = ["tls"] }
 url = "2"
 magic_migrate = "1.0"
 toml = "0.8"
-cache_diff = { version = "1.0.0", features = ["bullet_stream"] }
+cache_diff.workspace = true
 
 [dev-dependencies]
 libcnb-test = "=0.26.1"

buildpacks/ruby/src/layers/bundle_download_layer.rs

@@ -16,7 +16,7 @@ use libcnb::data::layer_name;
 use libcnb::layer::{EmptyLayerCause, LayerState};
 use libcnb::layer_env::{LayerEnv, ModificationBehavior, Scope};
 use libcnb::Env;
-use magic_migrate::{try_migrate_deserializer_chain, TryMigrate};
+use magic_migrate::TryMigrate;
 use serde::{Deserialize, Serialize};
 use std::io::Stdout;
 use std::path::Path;
@@ -70,24 +70,15 @@ pub(crate) fn handle(
 }
 
 pub(crate) type Metadata = MetadataV1;
-try_migrate_deserializer_chain!(
-    deserializer: toml::Deserializer::new,
-    error: MetadataError,
-    chain: [MetadataV1],
-);
 
-#[derive(Deserialize, Serialize, Debug, Clone, CacheDiff)]
+#[derive(Deserialize, Serialize, Debug, Clone, CacheDiff, TryMigrate)]
+#[try_migrate(from = None)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV1 {
     #[cache_diff(rename = "Bundler version")]
     pub(crate) version: ResolvedBundlerVersion,
 }
 
-#[derive(Debug, thiserror::Error)]
-pub(crate) enum MetadataError {
-    // Update if migrating between a metadata version can error
-}
-
 fn download_bundler(
     bullet: Print<SubBullet<Stdout>>,
     env: &Env,

buildpacks/ruby/src/layers/bundle_install_layer.rs

@@ -30,7 +30,7 @@ use libcnb::{
     layer_env::{LayerEnv, ModificationBehavior, Scope},
     Env,
 };
-use magic_migrate::{try_migrate_deserializer_chain, TryMigrate};
+use magic_migrate::TryMigrate;
 use serde::{Deserialize, Serialize};
 use std::io::Stdout;
 use std::{path::Path, process::Command};
@@ -121,22 +121,19 @@ pub(crate) fn handle(
 }
 
 pub(crate) type Metadata = MetadataV3;
-try_migrate_deserializer_chain!(
-    chain: [MetadataV1, MetadataV2, MetadataV3],
-    error: MetadataMigrateError,
-    deserializer: toml::Deserializer::new,
-);
 
-#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq)]
+#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, TryMigrate)]
 #[serde(deny_unknown_fields)]
+#[try_migrate(from = None)]
 pub(crate) struct MetadataV1 {
     pub(crate) stack: String,
     pub(crate) ruby_version: ResolvedRubyVersion,
     pub(crate) force_bundle_install_key: String,
     pub(crate) digest: MetadataDigest, // Must be last for serde to be happy https://github.com/toml-rs/toml-rs/issues/142
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq)]
+#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, TryMigrate)]
+#[try_migrate(from = MetadataV1)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV2 {
     pub(crate) distro_name: String,
@@ -147,7 +144,8 @@ pub(crate) struct MetadataV2 {
     pub(crate) digest: MetadataDigest, // Must be last for serde to be happy https://github.com/toml-rs/toml-rs/issues/142
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, CacheDiff)]
+#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, CacheDiff, TryMigrate)]
+#[try_migrate(from = MetadataV2)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV3 {
     #[cache_diff(rename = "OS Distribution")]

buildpacks/ruby/src/layers/ruby_install_layer.rs

@@ -25,7 +25,7 @@ use flate2::read::GzDecoder;
 use libcnb::data::layer_name;
 use libcnb::layer::{EmptyLayerCause, LayerState};
 use libcnb::layer_env::LayerEnv;
-use magic_migrate::{try_migrate_deserializer_chain, TryMigrate};
+use magic_migrate::TryMigrate;
 use serde::{Deserialize, Serialize};
 use std::io::{self, Stdout};
 use std::path::Path;
@@ -85,14 +85,16 @@ fn install_ruby(metadata: &Metadata, layer_path: &Path) -> Result<(), RubyBuildp
     Ok(())
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone)]
+#[derive(Deserialize, Serialize, Debug, Clone, TryMigrate)]
+#[try_migrate(from = None)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV1 {
     pub(crate) stack: String,
     pub(crate) version: ResolvedRubyVersion,
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq)]
+#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, TryMigrate)]
+#[try_migrate(from = MetadataV1)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV2 {
     pub(crate) distro_name: String,
@@ -101,7 +103,8 @@ pub(crate) struct MetadataV2 {
     pub(crate) ruby_version: ResolvedRubyVersion,
 }
 
-#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, CacheDiff)]
+#[derive(Deserialize, Serialize, Debug, Clone, Eq, PartialEq, CacheDiff, TryMigrate)]
+#[try_migrate(from = MetadataV2)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct MetadataV3 {
     #[cache_diff(rename = "OS Distribution")]
@@ -123,11 +126,6 @@ impl MetadataV3 {
 }
 
 pub(crate) type Metadata = MetadataV3;
-try_migrate_deserializer_chain!(
-    chain: [MetadataV1, MetadataV2, MetadataV3],
-    error: MetadataMigrateError,
-    deserializer: toml::Deserializer::new,
-);
 
 #[derive(thiserror::Error, Debug)]
 pub(crate) enum MetadataMigrateError {

commons/Cargo.toml

@@ -25,7 +25,7 @@ walkdir = "2"
 filetime = "0.2"
 magic_migrate = "1.0.1"
 toml = "0.8"
-cache_diff = "1.0"
+cache_diff.workspace = true
 
 [dev-dependencies]
 filetime = "0.2"

commons/src/layer/diff_migrate.rs

@@ -93,7 +93,7 @@ use bullet_stream as _;
 ///   When a `CacheDiff::diff` is empty, the layer is kept and the old data is returned. Otherwise,
 ///   the layer is deleted and the changes are returned.
 ///
-/// **TUTORIAL:** In the [`diff_migrate`] module docs
+/// **TUTORIAL:** In the [`crate::layer::diff_migrate`] module docs
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct DiffMigrateLayer {
     /// Whether the layer is intended for build.
@@ -138,7 +138,7 @@ impl DiffMigrateLayer {
     /// When given a prior [`LayerRename::from`] that exists, but the [`LayerRename::to`]
     /// does not, then the contents of the prior layer will be copied before being deleted.
     ///
-    /// After that this function callse [`cached_layer`] on the new layer.
+    /// After that this function calls [`crate::layer::diff_migrate::DiffMigrateLayer::cached_layer`] on the new layer.
     ///
     /// # Panics
     ///
@@ -320,10 +320,11 @@ mod tests {
     use libcnb::data::layer_name;
     use libcnb::generic::{GenericMetadata, GenericPlatform};
     use libcnb::layer::{EmptyLayerCause, InvalidMetadataAction, LayerState, RestoredLayerAction};
-    use magic_migrate::{migrate_toml_chain, try_migrate_deserializer_chain, Migrate, TryMigrate};
+    use magic_migrate::TryMigrate;
     use std::convert::Infallible;
     /// Struct for asserting the behavior of `CacheBuddy`
-    #[derive(Debug, serde::Serialize, serde::Deserialize, Clone)]
+    #[derive(Debug, serde::Serialize, serde::Deserialize, Clone, TryMigrate)]
+    #[try_migrate(from = None)]
     #[serde(deny_unknown_fields)]
     struct TestMetadata {
         value: String,
@@ -337,7 +338,6 @@ mod tests {
             }
         }
     }
-    migrate_toml_chain! {TestMetadata}
 
     struct FakeBuildpack;
     impl libcnb::Buildpack for FakeBuildpack {
@@ -555,13 +555,15 @@ mod tests {
     }
 
     /// Struct for asserting the behavior of `invalid_metadata_action`
-    #[derive(serde::Deserialize, serde::Serialize, Debug, Clone)]
+    #[derive(serde::Deserialize, serde::Serialize, Debug, Clone, TryMigrate)]
+    #[try_migrate(from = None)]
     #[serde(deny_unknown_fields)]
     struct PersonV1 {
         name: String,
     }
     /// Struct for asserting the behavior of `invalid_metadata_action`
-    #[derive(serde::Deserialize, serde::Serialize, Debug, Clone)]
+    #[derive(serde::Deserialize, serde::Serialize, Debug, Clone, TryMigrate)]
+    #[try_migrate(from = PersonV1)]
     #[serde(deny_unknown_fields)]
     struct PersonV2 {
         name: String,
@@ -583,25 +585,11 @@ mod tests {
             }
         }
     }
-    #[derive(Debug, Eq, PartialEq)]
+    #[derive(Debug, Eq, PartialEq, thiserror::Error)]
+    #[error("Not Richard")]
     struct NotRichard {
         name: String,
     }
-    impl From<NotRichard> for PersonMigrationError {
-        fn from(value: NotRichard) -> Self {
-            PersonMigrationError::NotRichard(value)
-        }
-    }
-    #[derive(Debug, Eq, PartialEq, thiserror::Error)]
-    enum PersonMigrationError {
-        #[error("Not Richard")]
-        NotRichard(NotRichard),
-    }
-    try_migrate_deserializer_chain!(
-        deserializer: toml::Deserializer::new,
-        error: PersonMigrationError,
-        chain: [PersonV1, PersonV2],
-    );
 
     #[test]
     fn test_invalid_metadata_action() {