feat(ci-new): add show-features command to list documented features

1 files changed, 47 insertions, 0 deletions

diff --git a/mingling_ci/src/res/features.rs b/mingling_ci/src/res/features.rs
new file mode 100644
index 0000000..8009514
--- /dev/null
+++ b/mingling_ci/src/res/features.rs
@@ -0,0 +1,47 @@
+use mingling::{Program, macros::program_setup};
+
+use crate::ThisProgram;
+
+/// Manifest that declares the documented feature list.
+///
+/// Path is relative to the repo root (the CI's working directory).
+const FEATURES_MANIFEST: &str = "./mingling/Cargo.toml";
+
+/// The docs.rs feature list of `mingling`, the single source of truth for the
+/// feature combinations used by CI checks.
+#[derive(Default, Clone)]
+pub struct ResFeatureList {
+    pub list: Vec<String>,
+}
+
+#[program_setup]
+pub fn features_setup(p: &mut Program<ThisProgram>) {
+    p.with_resource(ResFeatureList {
+        list: docs_rs_features(),
+    });
+}
+
+/// Reads `[package.metadata.docs.rs].features` from `mingling/Cargo.toml`.
+#[must_use]
+fn docs_rs_features() -> Vec<String> {
+    let Ok(content) = std::fs::read_to_string(FEATURES_MANIFEST) else {
+        return Vec::new();
+    };
+    let Ok(toml_value) = content.parse::<toml::Value>() else {
+        return Vec::new();
+    };
+    toml_value
+        .get("package")
+        .and_then(|p| p.get("metadata"))
+        .and_then(|m| m.get("docs"))
+        .and_then(|d| d.get("rs"))
+        .and_then(|rs| rs.get("features"))
+        .and_then(|f| f.as_array())
+        .map(|features| {
+            features
+                .iter()
+                .filter_map(|v| v.as_str().map(str::to_string))
+                .collect()
+        })
+        .unwrap_or_default()
+}