fix(complete): Emit value terminators on zsh

Emit the user-defined value terminator into the zsh completion pattern
to avoid doubled rest-arguments definitions:

    $ my-app <TAB>
    _arguments:comparguments:325: doubled rest argument definition:
    *::second -- second set of of multi-length arguments:

https://github.com/clap-rs/clap/issues/3266#issuecomment-1007901407
noted that including the value terminator is one step towards a
robust solution for handling multiple multi-valued arguments.

This change does not yet handle automatically detecting when a value
terminator is needed, but it does add tests to ensure that
user-specified value terminators are used on zsh.

Related-to: #3022
Signed-off-by: David Aguilar <davvid@gmail.com>

clap_complete/src/shells/zsh.rs

@@ -626,8 +626,15 @@ fn write_positionals_of(p: &Command) -> String {
         debug!("write_positionals_of:iter: arg={}", arg.get_id());
 
         let num_args = arg.get_num_args().expect("built");
+        let cardinality_value;
         let cardinality = if num_args.max_values() > 1 {
-            "*:"
+            match arg.get_value_terminator() {
+                Some(terminator) => {
+                    cardinality_value = format!("*{}:", escape_value(terminator));
+                    cardinality_value.as_str()
+                }
+                None => "*:",
+            }
         } else if !arg.is_required_set() {
             ":"
         } else {

clap_complete/tests/bash.rs

@@ -84,6 +84,18 @@ fn value_hint() {
     );
 }
 
+#[test]
+fn value_terminator() {
+    let name = "my-app";
+    let cmd = common::value_terminator_command(name);
+    common::assert_matches_path(
+        "tests/snapshots/value_terminator.bash",
+        clap_complete::shells::Bash,
+        cmd,
+        name,
+    );
+}
+
 #[cfg(feature = "unstable-dynamic")]
 #[test]
 fn register_minimal() {

clap_complete/tests/common.rs

@@ -252,6 +252,15 @@ pub fn value_hint_command(name: &'static str) -> clap::Command {
         )
 }
 
+pub fn value_terminator_command(name: &'static str) -> clap::Command {
+    clap::Command::new(name).arg(
+        clap::Arg::new("arguments")
+            .help("multi-valued argument with a value terminator")
+            .num_args(1..)
+            .value_terminator(";"),
+    )
+}
+
 pub fn assert_matches_path(
     expected_path: impl AsRef<std::path::Path>,
     gen: impl clap_complete::Generator,

clap_complete/tests/elvish.rs

@@ -83,3 +83,15 @@ fn value_hint() {
         name,
     );
 }
+
+#[test]
+fn value_terminator() {
+    let name = "my-app";
+    let cmd = common::value_terminator_command(name);
+    common::assert_matches_path(
+        "tests/snapshots/value_terminator.elvish",
+        clap_complete::shells::Elvish,
+        cmd,
+        name,
+    );
+}

clap_complete/tests/fish.rs

@@ -83,3 +83,15 @@ fn value_hint() {
         name,
     );
 }
+
+#[test]
+fn value_terminator() {
+    let name = "my-app";
+    let cmd = common::value_terminator_command(name);
+    common::assert_matches_path(
+        "tests/snapshots/value_terminator.fish",
+        clap_complete::shells::Fish,
+        cmd,
+        name,
+    );
+}

clap_complete/tests/powershell.rs

@@ -83,3 +83,15 @@ fn value_hint() {
         name,
     );
 }
+
+#[test]
+fn value_terminator() {
+    let name = "my-app";
+    let cmd = common::value_terminator_command(name);
+    common::assert_matches_path(
+        "tests/snapshots/value_terminator.ps1",
+        clap_complete::shells::PowerShell,
+        cmd,
+        name,
+    );
+}

clap_complete/tests/snapshots/value_terminator.bash

@@ -0,0 +1,38 @@
+_my-app() {
+    local i cur prev opts cmds
+    COMPREPLY=()
+    cur="${COMP_WORDS[COMP_CWORD]}"
+    prev="${COMP_WORDS[COMP_CWORD-1]}"
+    cmd=""
+    opts=""
+
+    for i in ${COMP_WORDS[@]}
+    do
+        case "${cmd},${i}" in
+            ",$1")
+                cmd="my__app"
+                ;;
+            *)
+                ;;
+        esac
+    done
+
+    case "${cmd}" in
+        my__app)
+            opts="-h --help [arguments]..."
+            if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
+                COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
+                return 0
+            fi
+            case "${prev}" in
+                *)
+                    COMPREPLY=()
+                    ;;
+            esac
+            COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
+            return 0
+            ;;
+    esac
+}
+
+complete -F _my-app -o bashdefault -o default my-app

clap_complete/tests/snapshots/value_terminator.elvish

@@ -0,0 +1,26 @@
+
+use builtin;
+use str;
+
+set edit:completion:arg-completer[my-app] = {|@words|
+    fn spaces {|n|
+        builtin:repeat $n ' ' | str:join ''
+    }
+    fn cand {|text desc|
+        edit:complex-candidate $text &display=$text' '(spaces (- 14 (wcswidth $text)))$desc
+    }
+    var command = 'my-app'
+    for word $words[1..-1] {
+        if (str:has-prefix $word '-') {
+            break
+        }
+        set command = $command';'$word
+    }
+    var completions = [
+        &'my-app'= {
+            cand -h 'Print help'
+            cand --help 'Print help'
+        }
+    ]
+    $completions[$command]
+}

clap_complete/tests/snapshots/value_terminator.fish

@@ -0,0 +1 @@
+complete -c my-app -s h -l help -d 'Print help'

clap_complete/tests/snapshots/value_terminator.ps1

@@ -0,0 +1,32 @@
+
+using namespace System.Management.Automation
+using namespace System.Management.Automation.Language
+
+Register-ArgumentCompleter -Native -CommandName 'my-app' -ScriptBlock {
+    param($wordToComplete, $commandAst, $cursorPosition)
+
+    $commandElements = $commandAst.CommandElements
+    $command = @(
+        'my-app'
+        for ($i = 1; $i -lt $commandElements.Count; $i++) {
+            $element = $commandElements[$i]
+            if ($element -isnot [StringConstantExpressionAst] -or
+                $element.StringConstantType -ne [StringConstantType]::BareWord -or
+                $element.Value.StartsWith('-') -or
+                $element.Value -eq $wordToComplete) {
+                break
+        }
+        $element.Value
+    }) -join ';'
+
+    $completions = @(switch ($command) {
+        'my-app' {
+            [CompletionResult]::new('-h', 'h', [CompletionResultType]::ParameterName, 'Print help')
+            [CompletionResult]::new('--help', 'help', [CompletionResultType]::ParameterName, 'Print help')
+            break
+        }
+    })
+
+    $completions.Where{ $_.CompletionText -like "$wordToComplete*" } |
+        Sort-Object -Property ListItemText
+}

clap_complete/tests/snapshots/value_terminator.zsh

@@ -0,0 +1,30 @@
+#compdef my-app
+
+autoload -U is-at-least
+
+_my-app() {
+    typeset -A opt_args
+    typeset -a _arguments_options
+    local ret=1
+
+    if is-at-least 5.2; then
+        _arguments_options=(-s -S -C)
+    else
+        _arguments_options=(-s -C)
+    fi
+
+    local context curcontext="$curcontext" state line
+    _arguments "${_arguments_options[@]}" \
+'-h[Print help]' \
+'--help[Print help]' \
+'*;::arguments -- multi-valued argument with a value terminator:' \
+&& ret=0
+}
+
+(( $+functions[_my-app_commands] )) ||
+_my-app_commands() {
+    local commands; commands=()
+    _describe -t commands 'my-app commands' commands "$@"
+}
+
+_my-app "$@"

clap_complete/tests/zsh.rs

@@ -83,3 +83,15 @@ fn value_hint() {
         name,
     );
 }
+
+#[test]
+fn value_terminator() {
+    let name = "my-app";
+    let cmd = common::value_terminator_command(name);
+    common::assert_matches_path(
+        "tests/snapshots/value_terminator.zsh",
+        clap_complete::shells::Zsh,
+        cmd,
+        name,
+    );
+}