Synchronize GitHub Releases with the in-repo changelog

Cargo.toml

@@ -34,6 +34,7 @@ postgres-native-tls = "0.3"
 native-tls = "0.2"
 serde_path_to_error = "0.1.2"
 octocrab = "0.5"
+comrak = "0.8.2"
 
 [dependencies.serde]
 version = "1"

src/changelogs/mod.rs

@@ -0,0 +1,46 @@
+mod rustc;
+
+use comrak::{nodes::AstNode, Arena, ComrakOptions, ComrakRenderOptions};
+use std::collections::HashMap;
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug, serde::Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub(crate) enum ChangelogFormat {
+    Rustc,
+}
+
+pub(crate) struct Changelog {
+    versions: HashMap<String, String>,
+}
+
+impl Changelog {
+    pub(crate) fn parse(format: ChangelogFormat, content: &str) -> anyhow::Result<Self> {
+        match format {
+            ChangelogFormat::Rustc => rustc::RustcFormat::new(&Arena::new()).parse(content),
+        }
+    }
+
+    pub(crate) fn version(&self, version: &str) -> Option<&str> {
+        self.versions.get(version).map(|s| s.as_str())
+    }
+}
+
+fn render_for_github_releases<'a>(document: &'a AstNode<'a>) -> anyhow::Result<String> {
+    let mut content = Vec::new();
+    comrak::format_commonmark(
+        document,
+        &ComrakOptions {
+            render: ComrakRenderOptions {
+                // Prevent column width line breaks from appearing in the generated release
+                // notes. GitHub Releases insert <br>s for every line break in the markdown,
+                // mangling the output.
+                width: std::usize::MAX,
+
+                ..ComrakRenderOptions::default()
+            },
+            ..ComrakOptions::default()
+        },
+        &mut content,
+    )?;
+    Ok(String::from_utf8(content)?)
+}