gate cargo_metadata on rustc feature too

Author: klensy

Cargo.toml

@@ -16,7 +16,7 @@ rustc_version = "0.4"
 colored = "2"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
-cargo_metadata = "0.18"
+cargo_metadata = { version = "0.18", optional = true }
 crossbeam-channel = "0.5.6"
 bstr = "1.0.1"
 rustfix = "0.8.1"
@@ -53,4 +53,4 @@ test = false
 
 [features]
 default = ["rustc"]
-rustc = ["dep:cargo-platform"]
+rustc = ["dep:cargo-platform", "dep:cargo_metadata"]

src/diagnostics.rs

@@ -1,5 +1,6 @@
 //! Data structures for handling diagnostic output from tests.
 
+#[cfg(feature = "rustc")]
 use cargo_metadata::diagnostic::DiagnosticLevel;
 
 #[derive(Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq)]
@@ -19,6 +20,7 @@ pub enum Level {
     FailureNote = 0,
 }
 
+#[cfg(feature = "rustc")]
 impl From<DiagnosticLevel> for Level {
     fn from(value: DiagnosticLevel) -> Self {
         match value {