From a483cc97d56a770c4ccf91dfccf790a8c2d0c9fa Mon Sep 17 00:00:00 2001
From: Kim Altintop <kim@eagain.io>
Date: Wed, 29 Mar 2023 13:20:08 +0200
Subject: core: version each metadata type separately

It turns out to be preferable to be able to break one type without
affecting the other.

So instead of the global SpecVersion, use a separate FmtVersion for each
type. For compatibility, keep supporting spec_version fields (until next
major bump of the respective types' version).

Signed-off-by: Kim Altintop <kim@eagain.io>
---
 src/metadata/mirrors.rs | 72 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 5 deletions(-)

(limited to 'src/metadata/mirrors.rs')

diff --git a/src/metadata/mirrors.rs b/src/metadata/mirrors.rs
index 9124dd3..eb437c9 100644
--- a/src/metadata/mirrors.rs
+++ b/src/metadata/mirrors.rs
@@ -4,6 +4,7 @@
 use std::{
     borrow::Cow,
     collections::BTreeSet,
+    ops::Deref,
 };
 
 use url::Url;
@@ -12,13 +13,31 @@ use super::{
     Custom,
     DateTime,
     Metadata,
-    SpecVersion,
 };
 use crate::{
     json::canonical,
     str::Varchar,
 };
 
+pub const FMT_VERSION: FmtVersion = FmtVersion(super::FmtVersion::new(0, 2, 0));
+
+#[derive(Clone, Eq, Ord, PartialEq, PartialOrd, serde::Serialize, serde::Deserialize)]
+pub struct FmtVersion(super::FmtVersion);
+
+impl Deref for FmtVersion {
+    type Target = super::FmtVersion;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Default for FmtVersion {
+    fn default() -> Self {
+        FMT_VERSION
+    }
+}
+
 #[derive(Clone, serde::Serialize, serde::Deserialize)]
 pub struct Mirror {
     pub url: Url,
@@ -42,9 +61,10 @@ pub enum Kind {
     Unknown(Varchar<String, 16>),
 }
 
-#[derive(Clone, Default, serde::Serialize, serde::Deserialize)]
+#[derive(Clone, Default, serde::Deserialize)]
 pub struct Mirrors {
-    pub spec_version: SpecVersion,
+    #[serde(alias = "spec_version")]
+    pub fmt_version: FmtVersion,
     pub mirrors: Vec<Mirror>,
     pub expires: Option<DateTime>,
 }
@@ -67,9 +87,30 @@ impl<'a> From<&'a Mirrors> for Cow<'a, Mirrors> {
     }
 }
 
-#[derive(Clone, Default, serde::Serialize, serde::Deserialize)]
+impl serde::Serialize for Mirrors {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        use serde::ser::SerializeStruct;
+
+        let mut s = serializer.serialize_struct("Mirrors", 3)?;
+        let version_field = if self.fmt_version < FMT_VERSION {
+            "spec_version"
+        } else {
+            "fmt_version"
+        };
+        s.serialize_field(version_field, &self.fmt_version)?;
+        s.serialize_field("mirrors", &self.mirrors)?;
+        s.serialize_field("expires", &self.expires)?;
+        s.end()
+    }
+}
+
+#[derive(Clone, Default, serde::Deserialize)]
 pub struct Alternates {
-    pub spec_version: SpecVersion,
+    #[serde(alias = "spec_version")]
+    pub fmt_version: FmtVersion,
     pub alternates: BTreeSet<Url>,
     #[serde(default)]
     pub custom: Custom,
@@ -93,3 +134,24 @@ impl<'a> From<&'a Alternates> for Cow<'a, Alternates> {
         Self::Borrowed(a)
     }
 }
+
+impl serde::Serialize for Alternates {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        use serde::ser::SerializeStruct;
+
+        let mut s = serializer.serialize_struct("Alternates", 4)?;
+        let version_field = if self.fmt_version < FMT_VERSION {
+            "spec_version"
+        } else {
+            "fmt_version"
+        };
+        s.serialize_field(version_field, &self.fmt_version)?;
+        s.serialize_field("alternates", &self.alternates)?;
+        s.serialize_field("custom", &self.custom)?;
+        s.serialize_field("expires", &self.expires)?;
+        s.end()
+    }
+}
-- 
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