perf: inline public getters/setters, and use non-generic inner functions

To reduce compile-times and avoid some overhead to binary size, this will modify some of our
generic functions to use non-generic inner functions where possible. The inner functions are
marked carefully with `#[inline(never)]` to prevent being inlined by LLVM at their callsites

While looking for generic functions to optimize, I have also taken the opportunity to annotate
public non-generic getters and setters with `#[inline]` to ensure that LLVM will inline them
across crate boundaries. By default, only generic functions are automatically inlined, and
only when enabling fat LTO are constant functions reliably inlined across crate boundaries.

src/app/cosmic.rs

@@ -6,16 +6,16 @@ use std::collections::HashMap;
 use std::sync::Arc;
 
 use super::{Action, Application, ApplicationExt, Subscription};
-use crate::theme::{Theme, ThemeType, THEME};
-use crate::{keyboard_nav, Core, Element};
+use crate::theme::{THEME, Theme, ThemeType};
+use crate::{Core, Element, keyboard_nav};
 #[cfg(feature = "wayland")]
 use cctk::sctk::reexports::csd_frame::{WindowManagerCapabilities, WindowState};
 use cosmic_theme::ThemeMode;
-#[cfg(feature = "wayland")]
-use iced::event::wayland;
 #[cfg(not(any(feature = "multi-window", feature = "wayland")))]
 use iced::Application as IcedApplication;
-use iced::{window, Task};
+#[cfg(feature = "wayland")]
+use iced::event::wayland;
+use iced::{Task, window};
 use iced_futures::event::listen_with;
 use palette::color_difference::EuclideanDistance;
 
@@ -243,6 +243,7 @@ where
     }
 
     #[allow(clippy::too_many_lines)]
+    #[cold]
     pub fn subscription(&self) -> Subscription<crate::Action<T::Message>> {
         let window_events = listen_with(|event, _, id| {
             match event {
@@ -410,6 +411,7 @@ where
 
 impl<T: Application> Cosmic<T> {
     #[allow(clippy::unused_self)]
+    #[cold]
     pub fn close(&mut self) -> iced::Task<crate::Action<T::Message>> {
         if let Some(id) = self.app.core().main_window_id() {
             iced::window::close(id)
@@ -490,10 +492,10 @@ impl<T: Application> Cosmic<T> {
 
             Action::KeyboardNav(message) => match message {
                 keyboard_nav::Action::FocusNext => {
-                    return iced::widget::focus_next().map(crate::Action::Cosmic)
+                    return iced::widget::focus_next().map(crate::Action::Cosmic);
                 }
                 keyboard_nav::Action::FocusPrevious => {
-                    return iced::widget::focus_previous().map(crate::Action::Cosmic)
+                    return iced::widget::focus_previous().map(crate::Action::Cosmic);
                 }
                 keyboard_nav::Action::Escape => return self.app.on_escape(),
                 keyboard_nav::Action::Search => return self.app.on_search(),

src/app/mod.rs

@@ -17,10 +17,10 @@ pub mod settings;
 
 pub type Task<M> = iced::Task<crate::Action<M>>;
 
+pub use crate::Core;
 use crate::prelude::*;
 use crate::theme::THEME;
 use crate::widget::{container, horizontal_space, id_container, menu, nav_bar, popover};
-pub use crate::Core;
 use apply::Apply;
 use context_drawer::ContextDrawer;
 use iced::window;
@@ -28,6 +28,7 @@ use iced::{Length, Subscription};
 pub use settings::Settings;
 use std::borrow::Cow;
 
+#[cold]
 pub(crate) fn iced_settings<App: Application>(
     settings: Settings,
     flags: App::Flags,
@@ -681,11 +682,10 @@ impl<App: Application> ApplicationExt for App {
         };
 
         // Ensures visually aligned radii for content and window corners
-        let window_corner_radius =
-            crate::theme::active()
-                .cosmic()
-                .radius_s()
-                .map(|x| if x < 4.0 { x } else { x + 4.0 });
+        let window_corner_radius = crate::theme::active()
+            .cosmic()
+            .radius_s()
+            .map(|x| if x < 4.0 { x } else { x + 4.0 });
 
         let view_column = crate::widget::column::with_capacity(2)
             .push_maybe(if core.window.show_headerbar {
@@ -811,6 +811,7 @@ const EMBEDDED_FONTS: &[&[u8]] = &[
     include_bytes!("../../res/noto/NotoSansMono-Bold.ttf"),
 ];
 
+#[cold]
 fn preload_fonts() {
     let mut font_system = iced::advanced::graphics::text::font_system()
         .write()