fix(help): Integrate 'Possible Values:' into 'Arg::help'

This makes the formatting off as highlighted in #6056

Author: epage

clap_builder/src/output/help_template.rs

@@ -638,13 +638,10 @@ impl HelpTemplate<'_, '_> {
         let mut help_is_empty = help.is_empty();
         help.replace_newline_var();
 
-        if !spec_vals.is_empty() {
+        let next_line_specs = self.use_long && arg.is_some();
+        if !spec_vals.is_empty() && !next_line_specs {
             if !help_is_empty {
-                let sep = if self.use_long && arg.is_some() {
-                    "\n\n"
-                } else {
-                    " "
-                };
+                let sep = " ";
                 help.push_str(sep);
             }
             help.push_str(spec_vals);
@@ -711,6 +708,19 @@ impl HelpTemplate<'_, '_> {
                 }
             }
         }
+
+        if !spec_vals.is_empty() && next_line_specs {
+            let mut help = StyledStr::new();
+            if !help_is_empty {
+                let sep = "\n\n";
+                help.push_str(sep);
+            }
+            help.push_str(spec_vals);
+
+            help.wrap(avail_chars);
+            help.indent("", &trailing_indent);
+            self.writer.push_styled(&help);
+        }
     }
 
     /// Will use next line help on writing args.

tests/ui/help_cmd_stdout.toml

@@ -31,12 +31,12 @@ Options:
 
   -c, --config <MODE>
           Speed configuration
-          
-          [default: fast]
 
           Possible values:
           - fast
           - slow: slower than fast
+          
+          [default: fast]
 
   -f <FRUITS>
           List of fruits

tests/ui/help_flag_stdout.toml

@@ -31,12 +31,12 @@ Options:
 
   -c, --config <MODE>
           Speed configuration
-          
-          [default: fast]
 
           Possible values:
           - fast
           - slow: slower than fast
+          
+          [default: fast]
 
   -f <FRUITS>
           List of fruits