{"record":{"id":"530c86dec2e75926","repo":"rust-lang/cargo","slug":"couldn-t-find-username","errorCode":null,"errorMessage":"couldn't find username","messagePattern":"couldn't find username","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"src/sources/git/utils.rs","lineNumber":1816,"sourceCode":"                    debug!(\"github fast path is already a full commit hash {rev}\");\n                    return Ok(FastPathRev::NeedsFetch(oid));\n                }\n                rev\n            } else {\n                debug!(\"can't use github fast path with `rev = \\\"{}\\\"`\", rev);\n                return Ok(FastPathRev::Indeterminate);\n            }\n        }\n    };\n\n    // This expects GitHub urls in the form `github.com/user/repo` and nothing\n    // else\n    let mut pieces = url\n        .path_segments()\n        .ok_or_else(|| anyhow!(\"no path segments on url\"))?;\n    let username = pieces\n        .next()\n        .ok_or_else(|| anyhow!(\"couldn't find username\"))?;\n    let repository = pieces\n        .next()\n        .ok_or_else(|| anyhow!(\"couldn't find repository name\"))?;\n    if pieces.next().is_some() {\n        anyhow::bail!(\"too many segments on URL\");\n    }\n\n    // Trim off the `.git` from the repository, if present, since that's\n    // optional for GitHub and won't work when we try to use the API as well.\n    let repository = repository.strip_suffix(\".git\").unwrap_or(repository);\n\n    let url = format!(\n        \"https://api.github.com/repos/{}/{}/commits/{}\",\n        username, repository, github_branch_name,\n    );\n    debug!(\"attempting GitHub fast path for {}\", url);\n    let mut request =\n        Request::get(url).header(http::header::ACCEPT, \"application/vnd.github.3.sha\");","sourceCodeStart":1798,"sourceCodeEnd":1834,"githubUrl":"https://github.com/rust-lang/cargo/blob/495c385d0875c4ba51eb72ea0448a2d4c018b8d4/src/sources/git/utils.rs#L1798-L1834","documentation":"In the GitHub fast path, after `url.path_segments()` returns an iterator, Cargo expects the first segment to be the GitHub username/org. If `pieces.next()` returns `None` (the URL path is empty, e.g. `https://github.com/`), this error fires. It indicates a GitHub URL truncated before the `user` segment.","triggerScenarios":"A git dependency URL like `https://github.com/` or `https://github.com` (no user/repo segments) reaching the fast path. The URL parsed successfully and had path segments (so 142 did not fire) but the first segment is missing.","commonSituations":"Truncated git URL in `Cargo.toml` from a bad copy-paste; environment variable substitution (`$REPO_URL`) producing an empty user; templated config that dropped the path.","solutions":["Set the git dependency URL to the full `https://github.com/<user>/<repo>` form.","Check any env-var or CI template that generates the URL for truncation.","Lint dependency URLs in a pre-commit hook."],"exampleFix":"# before\n[dependencies]\nx = { git = \"https://github.com/\" }\n\n# after\n[dependencies]\nx = { git = \"https://github.com/rust-lang/cargo\" }","handlingStrategy":"validation","validationCode":"fn require_user_repo(u: &url::Url) -> Result<(&str, &str), anyhow::Error> {\n    let mut s = u.path_segments().ok_or_else(|| anyhow!(\"no path segments\"))?;\n    let user = s.next().ok_or_else(|| anyhow!(\"no username\"))?;\n    let repo = s.next().ok_or_else(|| anyhow!(\"no repo\"))?;\n    Ok((user, repo))\n}","typeGuard":"fn url_has_user_segment(u: &url::Url) -> bool {\n    u.path_segments().and_then(|mut s| s.next()).filter(|s| !s.is_empty()).is_some()\n}","tryCatchPattern":"let username = match pieces.next() { Some(u) if !u.is_empty() => u, _ => return Ok(FastPathRev::Indeterminate) };","preventionTips":["Validate dependency URLs resolve to a repo before committing.","Reject GitHub URLs without a `user/repo` pair in CI lint.","Use copy-to-clipboard from the GitHub repo root."],"tags":["cargo","git","url-parsing","github-fast-path","configuration"],"backgroundTag":null,"analyzedSha":"495c385d0875c4ba51eb72ea0448a2d4c018b8d4","analyzedAt":"2026-08-11T17:42:36.556Z","contentChangedAt":"2026-08-11T17:42:36.556Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}