{"record":{"id":"7e25ceedc767d264","repo":"cross-rs/cross","slug":"unsupported-rust-target-for-file-file-name-unknown-libc","errorCode":null,"errorMessage":"unsupported rust target for file {file_name}: unknown libc version","messagePattern":"unsupported rust target for file (.+?): unknown libc version","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"xtask/src/crosstool.rs","lineNumber":353,"sourceCode":"    }\n    if ct_gcc.starts_with('\\n') {\n        ct_gcc.remove(0);\n    }\n    contents = contents\n        .replacen(\"%CT_GCC_V%\", &ct_gcc_v, 1)\n        .replacen(\"%CT_GCC%\", &ct_gcc, 1);\n\n    // configure the libc versions\n    let (key, libc_v, mut libc, extras) = if file_name.contains(\"gnu\") {\n        configure_glibc(glibc_version)?\n    } else if file_name.contains(\"uclibc\") {\n        configure_uclibc(uclibc_version)?\n    } else if file_name.contains(\"musl\") {\n        configure_musl(musl_version)?\n    } else if file_name.contains(\"none\") {\n        configure_newlib(newlib_version)?\n    } else {\n        eyre::bail!(\"unsupported rust target for file {file_name}: unknown libc version\");\n    };\n    if libc.starts_with('\\n') {\n        libc.remove(0);\n    }\n    contents = contents\n        .replacen(&format!(\"%CT_{key}_V%\"), &libc_v, 1)\n        .replacen(&format!(\"%CT_{key}%\"), &libc, 1);\n    if let Some(extras) = extras {\n        contents = contents.replacen(&format!(\"%CT_{key}_EXTRAS%\"), &extras, 1);\n    }\n\n    // configure the `CT_LINUX` values\n    if file_name.contains(\"linux\") {\n        let linux_versions: Vec<&str> = linux_version.split('.').collect();\n        if !matches!(linux_versions.len(), 2 | 3) {\n            eyre::bail!(\"invalid linux version, got {linux_version}\");\n        }\n        let linux_major = linux_versions[0].parse::<u32>()?;","sourceCodeStart":335,"sourceCodeEnd":371,"githubUrl":"https://github.com/cross-rs/cross/blob/8c1a8aa4b661711f4b7b6ac07c2e8929ce2f7d27/xtask/src/crosstool.rs#L335-L371","documentation":"configure_target derives crosstool-ng configuration from the Rust target triple encoded in the file name. It selects the libc configuration by substring: uclibc, musl, or 'none' (newlib for bare-metal). If the file name contains none of these markers, no libc can be configured and it bails with this error.","triggerScenarios":"configure_crosstool is called with a target whose file name has no 'uclibc', 'musl', or 'none' substring — e.g. a gnu/EABI target like 'arm-unknown-linux-gnueabihf' or 'x86_64-pc-windows-msvc' passed into the crosstool pipeline.","commonSituations":"Adding a new target to the support matrix that uses glibc (gnu) — the script only covers uclibc/musl/newlib; a typo in the target triple; running the cross-compile setup for a host/Windows target.","solutions":["Pass a Rust target whose triple includes musl (e.g. x86_64-unknown-linux-musl) or uclibc or a bare-metal 'none-eabi' target","Check the target triple for typos (e.g. 'musll' instead of 'musl')","If glibc support is needed, add a configure_glibc branch checking for \"gnu\" in file_name"],"exampleFix":"// before\nlet target = \"x86_64-unknown-linux-gnu\";\n// after\nlet target = \"x86_64-unknown-linux-musl\";","handlingStrategy":"validation","validationCode":"fn has_supported_libc(target: &str) -> bool {\n    target.contains(\"uclibc\") || target.contains(\"musl\") || target.contains(\"none\")\n}\nassert!(has_supported_libc(rust_target), \"unsupported libc in target: {rust_target}\");","typeGuard":"fn is_cross_target_supported(triple: &str) -> bool {\n    [\"uclibc\", \"musl\", \"none\"].iter().any(|m| triple.contains(m))\n}","tryCatchPattern":"match configure_crosstool(&target) {\n    Ok(cfg) => cfg,\n    Err(e) if e.to_string().contains(\"unknown libc version\") => {\n        eprintln!(\"target {target} uses an unconfigured libc; use a musl/uclibc/none target\");\n        std::process::exit(1);\n    }\n    Err(e) => return Err(e),\n}","preventionTips":["Maintain the target allowlist and cross-check new targets against libc markers","Verify target triples with `rustc --print target-list` before adding them","Note glibc (gnu) targets are intentionally unsupported here — do not add them without code changes"],"tags":["crosstool","cross-compilation","target","config"],"backgroundTag":"unsupported-config-value","analyzedSha":"8c1a8aa4b661711f4b7b6ac07c2e8929ce2f7d27","analyzedAt":"2026-09-13T15:10:43.988Z","contentChangedAt":"2026-09-13T15:10:43.988Z","schemaVersion":2},"datasetVersion":"2026-09-16T09:17:16.951Z"}