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fix(parse): don't split unknown --key=value into two positional args #628

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fix(parse): don't split unknown --key=value into two positional args #628

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41 changes: 38 additions & 3 deletions lib/src/parse.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -454,11 +454,11 @@ fn parse_partial_with_env(
if enable_flags && w.starts_with("--") {
grouped_flag = false;
let (word, val) = w.split_once('=').unwrap_or_else(|| (&w, ""));
if !val.is_empty() {
input.push_front(val.to_string());
}
if let Some(f) = out.available_flags.get(word) {
if f.arg.is_some() {
if !val.is_empty() {
input.push_front(val.to_string());
}
out.flag_awaiting_value.push(Arc::clone(f));
Comment on lines 458 to 462
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@gemini-code-assist gemini-code-assist Bot May 10, 2026

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medium

The current implementation moves the push_front logic inside the f.arg.is_some() block. While this correctly fixes the issue for unknown flags, it introduces a change in behavior for known flags that do not take arguments (e.g., boolean flags).

Previously, a value provided via = to a boolean flag (e.g., --verbose=true) would be pushed back and treated as a subsequent positional argument. With this change, that value is silently swallowed.

To maintain consistency with the short-flag parsing logic (lines 488-494), which pushes the remainder regardless of whether the flag takes an argument, consider moving the push_front call outside the f.arg.is_some() check but still within the if let Some(f) block. This ensures that unknown flags are still treated as single positional arguments while preserving existing behavior for known flags.

                if !val.is_empty() {
                    input.push_front(val.to_string());
                }
                if f.arg.is_some() {
                    out.flag_awaiting_value.push(Arc::clone(f));

} else if f.count {
let arr = out
Expand Down Expand Up @@ -1312,6 +1312,41 @@ mod tests {
}
}

#[test]
fn test_arg_var_true_unknown_long_eq_flag_not_split() {
// Regression: `--unknown=value` against a spec with only a variadic
// positional must be captured as a single arg, not split into
// `--unknown=value` plus a trailing `value`.
let cmd = SpecCommand::builder()
.name("test")
.arg(
SpecArg::builder()
.name("args")
.var(true)
.required(false)
.build(),
)
.build();
let spec = Spec {
name: "test".to_string(),
bin: "test".to_string(),
cmd,
..Default::default()
};

let input = vec!["test".to_string(), "--depth=3".to_string()];
let parsed = parse(&spec, &input).unwrap();

assert_eq!(parsed.args.len(), 1);
let value = parsed.args.values().next().unwrap();
match value {
ParseValue::MultiString(v) => {
assert_eq!(v, &vec!["--depth=3".to_string()]);
}
_ => panic!("Expected MultiString, got {:?}", value),
}
}

#[test]
fn test_arg_var_false_with_default_remains_string() {
// When arg has var=false (default), the default should still be String
Expand Down