{"record":{"id":"cba7c8c42116fb7d","repo":"cross-rs/cross","slug":"could-not-determine-what-toolchain-to-use-for-image","errorCode":null,"errorMessage":"could not determine what toolchain to use for image, defaulting to `{}`","messagePattern":"could not determine what toolchain to use for image, defaulting to `(.+?)`","errorType":"console","errorClass":null,"httpStatus":null,"severity":"warning","filePath":"src/docker/image.rs","lineNumber":78,"sourceCode":"                    // pick the platform with the same architecture\n                    same_arch.first().expect(\"should contain one element\")\n                } else if let Some(platform) = same_arch\n                    .iter()\n                    .find(|platform| &platform.os == engine.os.as_ref().unwrap_or(&Os::Linux))\n                {\n                    *platform\n                } else if let Some(platform) =\n                    same_arch.iter().find(|platform| platform.os == Os::Linux)\n                {\n                    // container engine should be fine with linux\n                    platform\n                } else {\n                    let platform = self\n                        .toolchain\n                        .first()\n                        .expect(\"should be at least one platform\");\n                    // FIXME: Don't throw away\n                    msg_info.warn(\n                        format_args!(\"could not determine what toolchain to use for image, defaulting to `{}`\", platform.target),\n                    ).ok();\n                    platform\n                }\n            };\n            Ok(Image {\n                platform: platform.clone(),\n                name,\n            })\n        }\n    }\n}\n\nimpl<T: AsRef<str>> From<T> for PossibleImage {\n    fn from(s: T) -> Self {\n        PossibleImage {\n            reference: s.as_ref().to_owned().into(),\n            toolchain: vec![],","sourceCodeStart":60,"sourceCodeEnd":96,"githubUrl":"https://github.com/cross-rs/cross/blob/8c1a8aa4b661711f4b7b6ac07c2e8929ce2f7d27/src/docker/image.rs#L60-L96","documentation":"When converting an image specification to a definite image, cross tries to determine which platform/toolchain entry to use. If it cannot disambiguate, it falls back to the first platform's target and warns that it is defaulting, discarding the other candidates (the FIXME: Don't throw away comment).","triggerScenarios":"Calling to_definite_with on an Image whose toolchain/platform list has multiple entries or lacks the metadata needed to pick a target for the current host, so cross defaults to `self.toolchain.first()`.","commonSituations":"Custom or multi-target images defined in Cross.toml where the image name/toolchain hint does not uniquely map to a platform; images built with unusual tags cross cannot parse.","solutions":["Check that the image/toolchain definition in Cross.toml names a single, explicit target so no defaulting is needed.","Set an explicit `target.<triple>.image` entry for the targets you build instead of relying on inference.","Verify the image tag follows the conventions cross expects (e.g. includes the target triple) so toolchain detection succeeds."],"exampleFix":"# before (Cross.toml)\n[build]\nimage = \"myimage:latest\"\n\n# after\n[target.aarch64-unknown-linux-gnu]\nimage = \"myimage:aarch64-unknown-linux-gnu\"","handlingStrategy":"validation","validationCode":"// Ensure each target has an explicit image before building\nfor target in targets {\n    assert!(config.target.get(target).and_then(|t| t.image.as_ref()).is_some(),\n        \"no explicit image for {}\", target);\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Always define target.<triple>.image explicitly for custom images","Include the target triple in image tags so cross can infer the toolchain","Avoid multi-entry toolchain lists in image definitions"],"tags":["docker","image","toolchain","fallback"],"backgroundTag":"invalid-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"}