feat(complete): Support require_equals in completion engine

clap_complete/src/engine/complete.rs

@@ -88,7 +88,10 @@ pub fn complete(
                 });
 
                 if let Some(opt) = opt {
-                    if opt.get_num_args().expect("built").takes_values() && value.is_none() {
+                    if opt.get_num_args().expect("built").takes_values()
+                        && value.is_none()
+                        && !opt.is_require_equals_set()
+                    {
                         next_state = ParseState::Opt((opt, 1));
                     };
                 } else if pos_allows_hyphen(current_cmd, pos_index) {
@@ -478,9 +481,16 @@ fn longs_and_visible_aliases(p: &clap::Command) -> Vec<CompletionCandidate> {
     p.get_arguments()
         .filter_map(|a| {
             a.get_long_and_visible_aliases().map(|longs| {
-                longs
-                    .into_iter()
-                    .map(|s| populate_arg_candidate(CompletionCandidate::new(format!("--{s}")), a))
+                longs.into_iter().map(|s| {
+                    let suffix = if a.is_require_equals_set()
+                        && a.get_num_args().expect("built").takes_values()
+                    {
+                        "="
+                    } else {
+                        ""
+                    };
+                    populate_arg_candidate(CompletionCandidate::new(format!("--{s}{suffix}")), a)
+                })
             })
         })
         .flatten()
@@ -495,7 +505,15 @@ fn hidden_longs_aliases(p: &clap::Command) -> Vec<CompletionCandidate> {
         .filter_map(|a| {
             a.get_aliases().map(|longs| {
                 longs.into_iter().map(|s| {
-                    populate_arg_candidate(CompletionCandidate::new(format!("--{s}")), a).hide(true)
+                    let suffix = if a.is_require_equals_set()
+                        && a.get_num_args().expect("built").takes_values()
+                    {
+                        "="
+                    } else {
+                        ""
+                    };
+                    populate_arg_candidate(CompletionCandidate::new(format!("--{s}{suffix}")), a)
+                        .hide(true)
                 })
             })
         })

clap_complete/tests/testsuite/engine.rs

@@ -1443,6 +1443,58 @@ pos-c
     );
 }
 
+#[test]
+fn suggest_require_equals() {
+    let mut cmd = Command::new("exhaustive")
+        .arg(
+            clap::Arg::new("format")
+                .long("format")
+                .require_equals(true)
+                .value_parser(["json", "yaml", "toml"]),
+        )
+        .arg(
+            clap::Arg::new("name")
+                .long("name")
+                .short('n'),
+        );
+
+    // When completing after an empty input, --format should appear with = appended
+    assert_data_eq!(
+        complete!(cmd, " [TAB]"),
+        snapbox::str![[r#"
+--format=
+--name
+--help	Print help
+"#]]
+    );
+
+    // Should complete values after --format=
+    assert_data_eq!(
+        complete!(cmd, "--format=[TAB]"),
+        snapbox::str![[r#"
+--format=json
+--format=yaml
+--format=toml
+"#]]
+    );
+
+    // Should complete values after --format=j
+    assert_data_eq!(
+        complete!(cmd, "--format=j[TAB]"),
+        snapbox::str!["--format=json"]
+    );
+
+    // When typing --format (space), should NOT suggest values since require_equals forbids it
+    assert_data_eq!(
+        complete!(cmd, "--format [TAB]"),
+        snapbox::str![[r#"
+--format=
+--name
+--help	Print help
+"#]]
+    );
+}
+
 fn complete(cmd: &mut Command, args: impl AsRef<str>, current_dir: Option<&Path>) -> String {
     let input = args.as_ref();
     let mut args = vec![std::ffi::OsString::from(cmd.get_name())];