rust-lang/cargo · error · anyhow::Error

patch for `{}` points to the same source, but patches must p

Error message

patch for `{}` points to the same source, but patches must point to different sources
help: check `{}` patch definition for `{}` in `{}`

What it means

Error "patch for `{}` points to the same source, but patches must point to different sources help: check `{}` patch definition for `{}` in `{}`" thrown in rust-lang/cargo.

Source

Thrown at src/workspace/registry.rs:436

                let (summary, should_unlock) =
                    summary_for_patch(&orig_patch, url, &locked, summaries, source.as_ref())
                        .await?;
                Ok::<_, anyhow::Error>((orig_patch, dep, summary, should_unlock))
            });
        }

        let unlocked_summaries = crate::util::block_on_stream(pending).map(|next| {
            let (orig_patch, dep, summary, should_unlock) = next?;
            debug!(
                "patch summary is {:?} should_unlock={:?}",
                summary, should_unlock
            );
            if let Some(unlock_id) = should_unlock {
                unlock_patches.push(((*orig_patch).clone(), unlock_id));
            }

            if *summary.package_id().source_id().canonical_url() == canonical {
                return Err(anyhow::anyhow!(
                    "patch for `{}` points to the same source, but patches must point to different sources\n\
                    help: check `{}` patch definition for `{}` in `{}`",
                    dep.package_name(),
                    dep.package_name(),
                    url,
                    orig_patch.loc
                ));
            }
            Ok(summary)
        }).collect::<CargoResult<Vec<_>>>()?;

        let mut name_and_version = HashSet::default();
        for summary in unlocked_summaries.iter() {
            let name = summary.package_id().name();
            let version = summary.package_id().version();
            if !name_and_version.insert((name, version)) {
                let duplicate_locations = patch_deps
                    .iter()

View on GitHub (pinned to 0e07a15537)

Solutions

1. Point the `[patch]` entry to a different source (e.g. a git fork or local path) instead of the same source it patches.
2. Remove the patch entry if it is redundant.

When it happens

Trigger: Thrown at src/workspace/registry.rs:436 when the library encounters an invalid state.

Common situations: Occurs when a `[patch]` entry points to the same source it is meant to patch. Patches must come from a different source (different registry, git URL, or path); adjust the patch location.

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/78763b5f350075eb.json. Report an issue: GitHub.