test(CHANGELOG): add --warn-only to cargo xtask changelog

Author: ErichDonGubler

xtask/src/changelog.rs

@@ -3,6 +3,7 @@ use xshell::Shell;
 
 pub(crate) fn check_changelog(shell: Shell, mut args: Arguments) -> anyhow::Result<()> {
     const CHANGELOG_PATH_RELATIVE: &str = "./CHANGELOG.md";
+    let warn_only = args.contains("--warn-only");
 
     let from_branch = args
         .free_from_str()
@@ -69,7 +70,12 @@ pub(crate) fn check_changelog(shell: Shell, mut args: Arguments) -> anyhow::Resu
             "one or more checks against `{}` failed; see above for details",
             CHANGELOG_PATH_RELATIVE,
         );
-        Err(anyhow::Error::msg(msg))
+        if warn_only {
+            log::warn!("{msg}");
+            Ok(())
+        } else {
+            Err(anyhow::Error::msg(msg))
+        }
     } else {
         Ok(())
     }

xtask/src/main.rs

@@ -52,6 +52,8 @@ Commands:
 
         `<to_commit>` is the tip of the `git diff` that will be used for checking (1).
 
+    --warn-only             Only reports issues as warnings, rather than reporting errors and forcing a non-zero exit code.
+
   miri
     Run all miri-compatible tests under miri. Requires a nightly toolchain
     with the x86_64-unknown-linux-gnu target and miri component installed.