tidy: add build-metrics-gated feature status serialization

Co-authored-by: Jane Losare-Lusby <jlusby42@gmail.com>

src/tools/tidy/Cargo.toml

@@ -12,11 +12,15 @@ miropt-test-tools = { path = "../miropt-test-tools" }
 walkdir = "2"
 ignore = "0.4.18"
 semver = "1.0"
+serde = { version = "1.0.125", features = ["derive"], optional = true }
 termcolor = "1.1.3"
 rustc-hash = "2.0.0"
 fluent-syntax = "0.11.1"
 similar = "2.5.0"
 
+[features]
+build-metrics = ["dep:serde"]
+
 [[bin]]
 name = "rust-tidy"
 path = "src/main.rs"

src/tools/tidy/src/features.rs

@@ -27,6 +27,7 @@ const FEATURE_GROUP_START_PREFIX: &str = "// feature-group-start";
 const FEATURE_GROUP_END_PREFIX: &str = "// feature-group-end";
 
 #[derive(Debug, PartialEq, Clone)]
+#[cfg_attr(feature = "build-metrics", derive(serde::Serialize))]
 pub enum Status {
     Accepted,
     Removed,
@@ -45,6 +46,7 @@ impl fmt::Display for Status {
 }
 
 #[derive(Debug, Clone)]
+#[cfg_attr(feature = "build-metrics", derive(serde::Serialize))]
 pub struct Feature {
     pub level: Status,
     pub since: Option<Version>,

src/tools/tidy/src/features/version.rs

@@ -8,6 +8,7 @@ mod tests;
 pub const VERSION_PLACEHOLDER: &str = "CURRENT_RUSTC_VERSION";
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+#[cfg_attr(feature = "build-metrics", derive(serde::Serialize))]
 pub enum Version {
     Explicit { parts: [u32; 3] },
     CurrentPlaceholder,