perf: Switch to &'static str by default

Originally, clap carried a lifetime parameter.  When moving away from
that, we took the approach that dynamically generated strings are always
supported and `&'static str` was just an optimization.

The problem is the code size increase from this is dramatic.  So we're
taking the opposite approach and making dynamic formatting opt-in under
the `string` feature flag.  When deciding on an implementation, I
favored the faster one rather than the one with smaller code size since
small code size can be gotten through other means.

Before: 567.2 KiB, 15.975 µs
After: 541.1 KiB, 9.7855 µs
With `string`: 576.6 KiB, 13.016 µs

Cargo.toml

@@ -60,7 +60,7 @@ default = [
   "suggestions",
 ]
 debug = ["clap_derive/debug", "dep:backtrace"] # Enables debug messages
-unstable-doc = ["derive", "cargo", "wrap_help", "env", "unicode", "perf", "unstable-replace", "unstable-grouped"] # for docs.rs
+unstable-doc = ["derive", "cargo", "wrap_help", "env", "unicode", "string", "unstable-replace", "unstable-grouped"] # for docs.rs
 
 # Used in default
 std = [] # support for no_std in a backwards-compatible way
@@ -74,7 +74,7 @@ cargo = ["dep:once_cell"] # Disable if you're not using Cargo, enables Cargo-env
 wrap_help = ["dep:terminal_size"]
 env = [] # Use environment variables during arg parsing
 unicode = ["dep:unicode-width", "dep:unicase"]  # Support for unicode characters in arguments and help messages
-perf = [] # Optimize for runtime performance
+string = []  # Allow runtime generated strings
 
 # In-work features
 unstable-replace = []

Makefile

@@ -15,8 +15,8 @@ MSRV?=1.60.0
 _FEATURES = minimal default wasm full debug release
 _FEATURES_minimal = --no-default-features --features "std"
 _FEATURES_default =
-_FEATURES_wasm = --features "deprecated derive cargo env unicode perf unstable-replace unstable-grouped"
-_FEATURES_full = --features "deprecated derive cargo env unicode perf unstable-replace unstable-grouped wrap_help"
+_FEATURES_wasm = --features "deprecated derive cargo env unicode string unstable-replace unstable-grouped"
+_FEATURES_full = --features "deprecated derive cargo env unicode string unstable-replace unstable-grouped wrap_help"
 _FEATURES_next = ${_FEATURES_full} --features unstable-v5
 _FEATURES_debug = ${_FEATURES_full} --features debug --features clap_complete/debug
 _FEATURES_release = ${_FEATURES_full} --release

clap_complete/src/generator/mod.rs

@@ -170,7 +170,7 @@ pub fn generate_to<G, S, T>(
 ) -> Result<PathBuf, Error>
 where
     G: Generator,
-    S: Into<clap::builder::Str>,
+    S: Into<String>,
     T: Into<OsString>,
 {
     cmd.set_bin_name(bin_name);
@@ -223,7 +223,7 @@ where
 pub fn generate<G, S>(gen: G, cmd: &mut clap::Command, bin_name: S, buf: &mut dyn Write)
 where
     G: Generator,
-    S: Into<clap::builder::Str>,
+    S: Into<String>,
 {
     cmd.set_bin_name(bin_name);
     _generate::<G, S>(gen, cmd, buf)
@@ -232,7 +232,7 @@ where
 fn _generate<G, S>(gen: G, cmd: &mut clap::Command, buf: &mut dyn Write)
 where
     G: Generator,
-    S: Into<clap::builder::Str>,
+    S: Into<String>,
 {
     cmd.build();
 

src/_features.rs

@@ -16,7 +16,7 @@
 //! * **env**: Turns on the usage of environment variables during parsing.
 //! * **unicode**: Turns on support for unicode characters (including emoji) in arguments and help messages.
 //! * **wrap_help**: Turns on the help text wrapping feature, based on the terminal size.
-//! * **perf**: Optimized for runtime performance.
+//! * **string**: Allow runtime generated strings
 //!
 //! #### Experimental features
 //!

src/builder/command.rs

@@ -70,8 +70,8 @@ pub struct Command {
     name: Str,
     long_flag: Option<Str>,
     short_flag: Option<char>,
-    display_name: Option<Str>,
-    bin_name: Option<Str>,
+    display_name: Option<String>,
+    bin_name: Option<String>,
     author: Option<Str>,
     version: Option<Str>,
     long_version: Option<Str>,
@@ -695,7 +695,7 @@ impl Command {
                 if let Some(f) = p.file_name() {
                     if let Some(s) = f.to_str() {
                         if self.bin_name.is_none() {
-                            self.bin_name = Some(Str::from(s.to_owned()));
+                            self.bin_name = Some(s.to_owned());
                         }
                     }
                 }
@@ -1376,7 +1376,7 @@ impl Command {
     /// # ;
     /// ```
     #[must_use]
-    pub fn bin_name(mut self, name: impl IntoResettable<Str>) -> Self {
+    pub fn bin_name(mut self, name: impl IntoResettable<String>) -> Self {
         self.bin_name = name.into_resettable().into_option();
         self
     }
@@ -1392,7 +1392,7 @@ impl Command {
     /// # ;
     /// ```
     #[must_use]
-    pub fn display_name(mut self, name: impl IntoResettable<Str>) -> Self {
+    pub fn display_name(mut self, name: impl IntoResettable<String>) -> Self {
         self.display_name = name.into_resettable().into_option();
         self
     }
@@ -3156,7 +3156,7 @@ impl Command {
     }
 
     /// Set binary name. Uses `&mut self` instead of `self`.
-    pub fn set_bin_name(&mut self, name: impl Into<Str>) {
+    pub fn set_bin_name(&mut self, name: impl Into<String>) {
         self.bin_name = Some(name.into());
     }
 
@@ -3889,7 +3889,7 @@ impl Command {
             "Command::_build_subcommand Setting bin_name of {} to {:?}",
             sc.name, bin_name
         );
-        sc.bin_name = Some(Str::from(bin_name));
+        sc.bin_name = Some(bin_name);
 
         if sc.display_name.is_none() {
             let self_display_name = if is_multicall_set {
@@ -3911,7 +3911,7 @@ impl Command {
                 "Command::_build_subcommand Setting display_name of {} to {:?}",
                 sc.name, display_name
             );
-            sc.display_name = Some(Str::from(display_name));
+            sc.display_name = Some(display_name);
         }
 
         // Ensure all args are built and ready to parse
@@ -3990,7 +3990,7 @@ impl Command {
                         "Command::_build_bin_names:iter: Setting bin_name of {} to {:?}",
                         sc.name, bin_name
                     );
-                    sc.bin_name = Some(Str::from(bin_name));
+                    sc.bin_name = Some(bin_name);
                 } else {
                     debug!(
                         "Command::_build_bin_names::iter: Using existing bin_name of {} ({:?})",
@@ -4018,7 +4018,7 @@ impl Command {
                         "Command::_build_bin_names:iter: Setting display_name of {} to {:?}",
                         sc.name, display_name
                     );
-                    sc.display_name = Some(Str::from(display_name));
+                    sc.display_name = Some(display_name);
                 } else {
                     debug!(
                         "Command::_build_bin_names::iter: Using existing display_name of {} ({:?})",

src/builder/os_str.rs

@@ -7,12 +7,14 @@ pub struct OsStr {
 }
 
 impl OsStr {
+    #[cfg(feature = "string")]
     pub(crate) fn from_string(name: std::ffi::OsString) -> Self {
         Self {
             name: Inner::from_string(name),
         }
     }
 
+    #[cfg(feature = "string")]
     pub(crate) fn from_ref(name: &std::ffi::OsStr) -> Self {
         Self {
             name: Inner::from_ref(name),
@@ -42,7 +44,7 @@ impl From<&'_ OsStr> for OsStr {
     }
 }
 
-#[cfg(feature = "perf")]
+#[cfg(feature = "string")]
 impl From<Str> for OsStr {
     fn from(id: Str) -> Self {
         match id.into_inner() {
@@ -52,10 +54,10 @@ impl From<Str> for OsStr {
     }
 }
 
-#[cfg(not(feature = "perf"))]
+#[cfg(not(feature = "string"))]
 impl From<Str> for OsStr {
     fn from(id: Str) -> Self {
-        Self::from_ref(std::ffi::OsStr::new(id.as_str()))
+        Self::from_static_ref(std::ffi::OsStr::new(id.into_inner().0))
     }
 }
 
@@ -69,31 +71,34 @@ impl From<&'_ Str> for OsStr {
     }
 }
 
-#[cfg(not(feature = "perf"))]
 impl From<&'_ Str> for OsStr {
     fn from(id: &'_ Str) -> Self {
-        Self::from_ref(std::ffi::OsStr::new(id.as_str()))
+        id.clone().into()
     }
 }
 
+#[cfg(feature = "string")]
 impl From<std::ffi::OsString> for OsStr {
     fn from(name: std::ffi::OsString) -> Self {
         Self::from_string(name)
     }
 }
 
+#[cfg(feature = "string")]
 impl From<&'_ std::ffi::OsString> for OsStr {
     fn from(name: &'_ std::ffi::OsString) -> Self {
         Self::from_ref(name.as_os_str())
     }
 }
 
+#[cfg(feature = "string")]
 impl From<std::string::String> for OsStr {
     fn from(name: std::string::String) -> Self {
         Self::from_string(name.into())
     }
 }
 
+#[cfg(feature = "string")]
 impl From<&'_ std::string::String> for OsStr {
     fn from(name: &'_ std::string::String) -> Self {
         Self::from_ref(name.as_str().as_ref())
@@ -238,7 +243,7 @@ impl PartialEq<OsStr> for std::ffi::OsString {
     }
 }
 
-#[cfg(feature = "perf")]
+#[cfg(feature = "string")]
 pub(crate) mod inner {
     #[derive(Clone)]
     pub(crate) enum Inner {
@@ -272,26 +277,18 @@ pub(crate) mod inner {
     }
 }
 
-#[cfg(not(feature = "perf"))]
+#[cfg(not(feature = "string"))]
 pub(crate) mod inner {
     #[derive(Clone)]
-    pub(crate) struct Inner(Box<std::ffi::OsStr>);
+    pub(crate) struct Inner(&'static std::ffi::OsStr);
 
     impl Inner {
-        pub(crate) fn from_string(name: std::ffi::OsString) -> Self {
-            Self(name.into_boxed_os_str())
-        }
-
-        pub(crate) fn from_ref(name: &std::ffi::OsStr) -> Self {
-            Self(Box::from(name))
-        }
-
         pub(crate) fn from_static_ref(name: &'static std::ffi::OsStr) -> Self {
-            Self::from_ref(name)
+            Self(name)
         }
 
         pub(crate) fn as_os_str(&self) -> &std::ffi::OsStr {
-            &self.0
+            self.0
         }
 
         pub(crate) fn into_os_string(self) -> std::ffi::OsString {

src/builder/resettable.rs

@@ -162,6 +162,12 @@ impl<I: Into<ValueParser>> IntoResettable<ValueParser> for I {
     }
 }
 
+impl<I: Into<String>> IntoResettable<String> for I {
+    fn into_resettable(self) -> Resettable<String> {
+        Resettable::Value(self.into())
+    }
+}
+
 impl<I: Into<StyledStr>> IntoResettable<StyledStr> for I {
     fn into_resettable(self) -> Resettable<StyledStr> {
         Resettable::Value(self.into())

src/builder/str.rs

@@ -5,12 +5,14 @@ pub struct Str {
 }
 
 impl Str {
+    #[cfg(feature = "string")]
     pub(crate) fn from_string(name: std::string::String) -> Self {
         Self {
             name: Inner::from_string(name),
         }
     }
 
+    #[cfg(feature = "string")]
     pub(crate) fn from_ref(name: &str) -> Self {
         Self {
             name: Inner::from_ref(name),
@@ -23,7 +25,6 @@ impl Str {
         }
     }
 
-    #[cfg(feature = "perf")]
     pub(crate) fn into_inner(self) -> Inner {
         self.name
     }
@@ -40,12 +41,14 @@ impl From<&'_ Str> for Str {
     }
 }
 
+#[cfg(feature = "string")]
 impl From<std::string::String> for Str {
     fn from(name: std::string::String) -> Self {
         Self::from_string(name)
     }
 }
 
+#[cfg(feature = "string")]
 impl From<&'_ std::string::String> for Str {
     fn from(name: &'_ std::string::String) -> Self {
         Self::from_ref(name.as_str())
@@ -211,7 +214,7 @@ impl PartialEq<Str> for std::string::String {
     }
 }
 
-#[cfg(feature = "perf")]
+#[cfg(feature = "string")]
 pub(crate) mod inner {
     #[derive(Clone)]
     pub(crate) enum Inner {
@@ -245,26 +248,18 @@ pub(crate) mod inner {
     }
 }
 
-#[cfg(not(feature = "perf"))]
+#[cfg(not(feature = "string"))]
 pub(crate) mod inner {
     #[derive(Clone)]
-    pub(crate) struct Inner(Box<str>);
+    pub(crate) struct Inner(pub(crate) &'static str);
 
     impl Inner {
-        pub(crate) fn from_string(name: std::string::String) -> Self {
-            Self(name.into_boxed_str())
-        }
-
-        pub(crate) fn from_ref(name: &str) -> Self {
-            Self(Box::from(name))
-        }
-
         pub(crate) fn from_static_ref(name: &'static str) -> Self {
-            Self::from_ref(name)
+            Self(name)
         }
 
         pub(crate) fn as_str(&self) -> &str {
-            &self.0
+            self.0
         }
 
         pub(crate) fn into_string(self) -> String {

src/util/id.rs

@@ -45,12 +45,14 @@ impl From<&'_ Str> for Id {
     }
 }
 
+#[cfg(feature = "string")]
 impl From<std::string::String> for Id {
     fn from(name: std::string::String) -> Self {
         Self(name.into())
     }
 }
 
+#[cfg(feature = "string")]
 impl From<&'_ std::string::String> for Id {
     fn from(name: &'_ std::string::String) -> Self {
         Self(name.into())

tests/examples.rs

@@ -18,6 +18,8 @@ fn example_tests() {
         "suggestions",
         #[cfg(feature = "unicode")]
         "unicode",
+        #[cfg(feature = "string")]
+        "string",
         #[cfg(feature = "wrap_help")]
         "wrap_help",
         #[cfg(feature = "unstable-replace")]

tests/ui.rs

@@ -18,6 +18,8 @@ fn ui_tests() {
         "suggestions",
         #[cfg(feature = "unicode")]
         "unicode",
+        #[cfg(feature = "string")]
+        "string",
         #[cfg(feature = "wrap_help")]
         "wrap_help",
         #[cfg(feature = "unstable-replace")]