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diff: accept clustered short options such as -qst and -ut #304

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b53b92a
diff: parse clusters of supported short options
SichenLiang Oct 13, 2026
d50d5ad
diff: simplify the parsing of short option clusters
sylvestre Oct 24, 2026
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158 changes: 129 additions & 29 deletions src/params.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -79,37 +79,40 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
}
continue;
}
if param == "-s" || param == "--report-identical-files" {
// A word of short options taking no argument, such as `-qst`. Other
// words are left whole for legacy numeric options and their diagnostics.
if let Some(short) = param
.to_str()
.and_then(|arg| arg.strip_prefix('-'))
.filter(|short| !short.is_empty() && short.bytes().all(|b| SHORT_OPTIONS.contains(&b)))
{
for option in short.bytes() {
apply_short_option(option, &mut params, &mut format)?;
}
continue;
}
if param == "--report-identical-files" {
params.report_identical_files = true;
continue;
}
if param == "-q" || param == "--brief" {
if param == "--brief" {
params.brief = true;
continue;
}
if param == "-t" || param == "--expand-tabs" {
if param == "--expand-tabs" {
params.expand_tabs = true;
continue;
}
if param == "--normal" {
if format.is_some() && format != Some(Format::Normal) {
return Err("Conflicting output style options".to_string());
}
format = Some(Format::Normal);
set_format(&mut format, Format::Normal)?;
continue;
}
if param == "-e" || param == "--ed" {
if format.is_some() && format != Some(Format::Ed) {
return Err("Conflicting output style options".to_string());
}
format = Some(Format::Ed);
if param == "--ed" {
set_format(&mut format, Format::Ed)?;
continue;
}
if param == "-y" || param == "--side-by-side" {
if format.is_some() && format != Some(Format::SideBySide) {
return Err("Conflicting output style option".to_string());
}
format = Some(Format::SideBySide);
if param == "--side-by-side" {
set_format(&mut format, Format::SideBySide)?;
continue;
}
if width_re.is_match(param.to_string_lossy().as_ref()) {
Expand Down Expand Up @@ -156,14 +159,13 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu

continue;
}
match match_context_diff_params(&param, next_param, format) {
match match_context_diff_params(&param, next_param, &mut format) {
Ok(DiffStyleMatch {
is_match,
context_count,
next_param_consumed,
}) => {
if is_match {
format = Some(Format::Context);
if context_count.is_some() {
context = context_count;
}
Expand All @@ -175,14 +177,13 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
}
Err(error) => return Err(error),
}
match match_unified_diff_params(&param, next_param, format) {
match match_unified_diff_params(&param, next_param, &mut format) {
Ok(DiffStyleMatch {
is_match,
context_count,
next_param_consumed,
}) => {
if is_match {
format = Some(Format::Unified);
if context_count.is_some() {
context = context_count;
}
Expand Down Expand Up @@ -249,6 +250,42 @@ pub fn parse_params<I: Iterator<Item = OsString>>(mut opts: Peekable<I>) -> Resu
Ok(params)
}

fn set_format(format: &mut Option<Format>, requested: Format) -> Result<(), String> {
if format.is_some() && *format != Some(requested) {
// Preserve the singular side-by-side diagnostic for compatibility.
let message = if requested == Format::SideBySide {
"Conflicting output style option"
} else {
"Conflicting output style options"
};
return Err(message.to_string());
}
*format = Some(requested);
Ok(())
}

/// The short options that take no argument, and can be grouped.
const SHORT_OPTIONS: &[u8] = b"ceqstuy";

fn apply_short_option(
option: u8,
params: &mut Params,
format: &mut Option<Format>,
) -> Result<(), String> {
match option {
b'c' => set_format(format, Format::Context)?,
b'e' => set_format(format, Format::Ed)?,
b'q' => params.brief = true,
b's' => params.report_identical_files = true,
b't' => params.expand_tabs = true,
b'u' => set_format(format, Format::Unified)?,
b'y' => set_format(format, Format::SideBySide)?,
// Callers only pass bytes of SHORT_OPTIONS.
_ => unreachable!("not a short option: {}", char::from(option)),
}
Ok(())
}

struct DiffStyleMatch {
is_match: bool,
context_count: Option<usize>,
Expand All @@ -258,17 +295,15 @@ struct DiffStyleMatch {
fn match_context_diff_params(
param: &OsString,
next_param: Option<&OsString>,
format: Option<Format>,
format: &mut Option<Format>,
) -> Result<DiffStyleMatch, String> {
const CONTEXT_RE: &str = r"^(-[cC](?<num1>\d*)|--context(=(?<num2>\d*))?|-(?<num3>\d+)c)$";
let regex = Regex::new(CONTEXT_RE).unwrap();
let is_match = regex.is_match(param.to_string_lossy().as_ref());
let mut context_count = None;
let mut next_param_consumed = false;
if is_match {
if format.is_some() && format != Some(Format::Context) {
return Err("Conflicting output style options".to_string());
}
set_format(format, Format::Context)?;
let captures = regex.captures(param.to_str().unwrap()).unwrap();
let num = captures
.name("num1")
Expand Down Expand Up @@ -302,17 +337,15 @@ fn match_context_diff_params(
fn match_unified_diff_params(
param: &OsString,
next_param: Option<&OsString>,
format: Option<Format>,
format: &mut Option<Format>,
) -> Result<DiffStyleMatch, String> {
const UNIFIED_RE: &str = r"^(-[uU](?<num1>\d*)|--unified(=(?<num2>\d*))?|-(?<num3>\d+)u)$";
let regex = Regex::new(UNIFIED_RE).unwrap();
let is_match = regex.is_match(param.to_string_lossy().as_ref());
let mut context_count = None;
let mut next_param_consumed = false;
if is_match {
if format.is_some() && format != Some(Format::Unified) {
return Err("Conflicting output style options".to_string());
}
set_format(format, Format::Unified)?;
let captures = regex.captures(param.to_str().unwrap()).unwrap();
let num = captures
.name("num1")
Expand Down Expand Up @@ -719,6 +752,64 @@ mod tests {
}
}
#[test]
fn short_option_clusters() {
for (cluster, format, brief, report_identical_files, expand_tabs) in [
("-cc", Format::Context, false, false, false),
("-ee", Format::Ed, false, false, false),
("-qq", Format::Normal, true, false, false),
("-ss", Format::Normal, false, true, false),
("-tt", Format::Normal, false, false, true),
("-uu", Format::Unified, false, false, false),
("-yy", Format::SideBySide, false, false, false),
("-cqt", Format::Context, true, false, true),
("-eqs", Format::Ed, true, true, false),
("-qst", Format::Normal, true, true, true),
("-uqt", Format::Unified, true, false, true),
("-yqs", Format::SideBySide, true, true, false),
] {
assert_eq!(
Ok(Params {
executable: os("diff"),
from: os("foo"),
to: os("bar"),
format,
brief,
report_identical_files,
expand_tabs,
..Default::default()
}),
parse_params(
[os("diff"), os(cluster), os("foo"), os("bar")]
.iter()
.cloned()
.peekable()
),
"{cluster}"
);
}
}
#[test]
fn partly_recognized_short_option_clusters() {
for options in [
vec!["-qg"],
vec!["-u", "-cX"],
vec!["-u", "-qcX"],
vec!["-c", "-uX"],
] {
let unknown = options.last().unwrap().to_string();
let args = ["diff"]
.into_iter()
.chain(options)
.chain(["foo", "bar"])
.map(os)
.collect::<Vec<_>>();
assert_eq!(
Err(format!("unrecognized option '{unknown}'")),
parse_params(args.into_iter().peekable())
);
}
}
#[test]
fn tabsize() {
assert_eq!(
Ok(Params {
Expand Down Expand Up @@ -965,5 +1056,14 @@ mod tests {
)
.is_err());
}
assert_eq!(
Err("Conflicting output style options".to_string()),
parse_params(
[os("diff"), os("-c"), os("-ut"), os("foo"), os("bar")]
.iter()
.cloned()
.peekable()
)
);
}
}
57 changes: 57 additions & 0 deletions tests/by-util/test_diff.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,63 @@ fn differences_brief() -> Result<(), Box<dyn std::error::Error>> {
Ok(())
}

#[test]
fn short_option_clusters() -> Result<(), Box<dyn std::error::Error>> {
let mut left = NamedTempFile::new()?;
left.write_all(b"one\ttwo\n")?;
let mut right = NamedTempFile::new()?;
right.write_all(b"one two\n")?;
let mut same = NamedTempFile::new()?;
same.write_all(b"one\ttwo\n")?;

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff")
.arg("-qs")
.arg(left.path())
.arg(right.path());
cmd.assert().code(predicate::eq(1)).stdout(format!(
"Files {} and {} differ\n",
left.path().to_string_lossy(),
right.path().to_string_lossy()
));

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff").arg("-sq").arg(left.path()).arg(same.path());
cmd.assert().code(predicate::eq(0)).stdout(format!(
"Files {} and {} are identical\n",
left.path().to_string_lossy(),
same.path().to_string_lossy()
));

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff")
.arg("-te")
.arg(right.path())
.arg(left.path());
cmd.assert()
.code(predicate::eq(1))
.stdout("1c\none two\n.\n");

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff")
.arg("-ue")
.arg(left.path())
.arg(right.path());
cmd.assert()
.code(predicate::eq(2))
.stderr(predicate::str::contains("Conflicting output style options"));

let mut cmd = cargo_bin_cmd!("diffutils");
cmd.arg("diff")
.arg("-qz")
.arg(left.path())
.arg(right.path());
cmd.assert()
.code(predicate::eq(2))
.stderr(predicate::str::contains("unrecognized option '-qz'"));
Ok(())
}

#[test]
fn missing_newline() -> Result<(), Box<dyn std::error::Error>> {
let mut file1 = NamedTempFile::new()?;
Expand Down