{"record":{"id":"bbb9287e6c7fbe13","repo":"nautechsystems/nautilus_trader","slug":"failed-to-serialize-strings-to-json","errorCode":null,"errorMessage":"Failed to serialize strings to JSON","messagePattern":"Failed to serialize strings to JSON","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"crates/core/src/ffi/parsing.rs","lineNumber":84,"sourceCode":"\n    arr.iter()\n        .map(|value| {\n            value\n                .as_str()\n                .expect(\"C string JSON array must contain only strings\")\n                .to_owned()\n        })\n        .collect()\n}\n\n/// Convert a slice of `String` into a C string pointer (JSON encoded).\n///\n/// # Panics\n///\n/// Panics if JSON serialization fails or if the generated string contains interior null bytes.\n#[must_use]\npub fn string_vec_to_bytes(strings: &[String]) -> *const c_char {\n    let json_string = serde_json::to_string(strings).expect(\"Failed to serialize strings to JSON\");\n    let c_string = CString::new(json_string).expect(\"JSON string contains interior null bytes\");\n\n    c_string.into_raw()\n}\n\n/// Convert a C bytes pointer into an owned `Option<HashMap<String, Value>>`.\n///\n/// # Safety\n///\n/// Assumes `ptr` is a valid C string pointer.\n///\n/// # Panics\n///\n/// Panics if `ptr` is not null but contains invalid UTF-8 or JSON.\n#[must_use]\npub unsafe fn optional_bytes_to_json(ptr: *const c_char) -> Option<HashMap<String, Value>> {\n    // SAFETY: A non-null pointer is valid under the caller's contract\n    unsafe { optional_json_from_cstr(ptr) }","sourceCodeStart":66,"sourceCodeEnd":102,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/core/src/ffi/parsing.rs#L66-L102","documentation":"Panic in `string_vec_to_bytes`: `serde_json::to_string(strings).expect(\"Failed to serialize strings to JSON\")` aborts if JSON serialization of the string slice fails. In practice `serde_json` cannot fail serializing a `&[String]`, so this panic indicates an internal/unexpected condition (e.g. an incompatible serde_json feature set or a corrupted state) rather than caller input. Documented under the function's # Panics section.","triggerScenarios":"Calling `string_vec_to_bytes` (directly or via `synthetic_instrument_components_to_cstr`) when `serde_json::to_string` returns an Err — an effectively unreachable path for plain string slices, kept as a fail-fast guard.","commonSituations":"Highly unusual: broken/custom serde_json builds, exotic `String` contents interacting with non-default serializer features, or future refactors changing the input type to something fallible to serialize.","solutions":["Verify serde_json is the standard, unmodified crate version per Cargo.lock (no patched forks)","Rebuild the crate; transient build/feature misconfigurations are the realistic cause","Check the input is a plain `&[String]` and no custom Serialize wrappers were introduced","If reproducible, file an issue — for `Vec<String>` this path is expected to be infallible"],"exampleFix":null,"handlingStrategy":"try-catch","validationCode":"// serialization of &[String] via serde_json is infallible; verify dependency integrity instead\n// cargo tree -i serde_json  # ensure no patched/forked serde_json","typeGuard":null,"tryCatchPattern":"let result = std::panic::catch_unwind(|| string_vec_to_bytes(strings));\nmatch result { Ok(p) => p, Err(_) => { eprintln!(\"string_vec_to_bytes panicked\"); std::ptr::null() } }","preventionTips":["Use the stock serde_json crate, no [patch] forks","Rebuild cleanly if serialization unexpectedly fails","Keep inputs as plain Vec<String>","Report reproducible panics upstream — this path is expected to be infallible"],"tags":["rust","ffi","json","panic","serialization"],"backgroundTag":"json-serialization-failed","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}