refactor(parser): Track subcommands with Box<str>

The overall hope is to allow a `&'static str`-only version of clap, so
we need to move off of `Str` where dynamic strings are required.  We
need it here for subcommands due to external subcommands.

This had minimal impact on code size (567.2 to 567.5 KiB)

clap_derive/src/derives/subcommand.rs

@@ -491,7 +491,7 @@ fn gen_from_arg_matches(variants: &[(&Variant, Item)]) -> TokenStream {
         };
 
         quote! {
-            if #subcommand_name_var == #sub_name && !#sub_arg_matches_var.contains_id("") {
+            if #subcommand_name_var.as_ref() == #sub_name && !#sub_arg_matches_var.contains_id("") {
                 return ::std::result::Result::Ok(Self :: #variant_name #constructor_block)
             }
         }
@@ -522,7 +522,7 @@ fn gen_from_arg_matches(variants: &[(&Variant, Item)]) -> TokenStream {
     let wildcard = match ext_subcmd {
         Some((span, var_name, str_ty)) => quote_spanned! { span=>
                 ::std::result::Result::Ok(Self::#var_name(
-                    ::std::iter::once(#str_ty::from(#subcommand_name_var))
+                    ::std::iter::once(#str_ty::from(#subcommand_name_var.as_ref()))
                     .chain(
                         #sub_arg_matches_var
                             .remove_many::<#str_ty>("")

src/builder/command.rs

@@ -3167,6 +3167,7 @@ impl Command {
     }
 
     #[inline]
+    #[cfg(debug_assertions)]
     pub(crate) fn get_name_str(&self) -> &Str {
         &self.name
     }

src/parser/matches/arg_matches.rs

@@ -6,6 +6,7 @@ use std::iter::{Cloned, Flatten, Map};
 use std::slice::Iter;
 
 // Internal
+#[cfg(debug_assertions)]
 use crate::builder::Str;
 use crate::parser::AnyValue;
 use crate::parser::AnyValueId;
@@ -839,7 +840,7 @@ impl ArgMatches {
     /// }
     /// ```
     /// [subcommand]: crate::Command::subcommand
-    pub fn remove_subcommand(&mut self) -> Option<(Str, ArgMatches)> {
+    pub fn remove_subcommand(&mut self) -> Option<(Box<str>, ArgMatches)> {
         self.subcommand.take().map(|sc| (sc.name, sc.matches))
     }
 
@@ -1138,7 +1139,7 @@ impl ArgMatches {
         }
 
         if let Some(ref sc) = self.subcommand {
-            if sc.name == name {
+            if sc.name.as_ref() == name {
                 return Some(sc);
             }
         }
@@ -1149,7 +1150,7 @@ impl ArgMatches {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub(crate) struct SubCommand {
-    pub(crate) name: Str,
+    pub(crate) name: Box<str>,
     pub(crate) matches: ArgMatches,
 }
 

src/parser/parser.rs

@@ -9,7 +9,6 @@ use clap_lex::RawOsStr;
 use clap_lex::RawOsString;
 
 // Internal
-use crate::builder::Str;
 use crate::builder::{Arg, Command};
 use crate::error::Error as ClapError;
 use crate::error::Result as ClapResult;
@@ -418,7 +417,7 @@ impl<'cmd> Parser<'cmd> {
             {
                 // Get external subcommand name
                 let sc_name = match arg_os.to_value() {
-                    Ok(s) => Str::from(s.to_owned()),
+                    Ok(s) => Box::from(s),
                     Err(_) => {
                         let _ = self.resolve_pending(matcher);
                         return Err(ClapError::invalid_utf8(
@@ -702,7 +701,7 @@ impl<'cmd> Parser<'cmd> {
                 }
             }
             matcher.subcommand(SubCommand {
-                name: sc.get_name_str().clone(),
+                name: Box::from(sc.get_name()),
                 matches: sc_matcher.into_inner(),
             });
         }