Replace serde's derive with custom proc macro

This replaces the existing `Deserialize` derive from serde with a
`ConfigDeserialize` derive. The goal of this new proc macro is to allow
a more error-friendly deserialization for the Alacritty configuration
file without having to manage a lot of boilerplate code inside the
configuration modules.

The first part of the derive macro is for struct deserialization. This
takes structs which have `Default` implemented and will only replace
fields which can be successfully deserialized. Otherwise the `log` crate
is used for printing errors. Since this deserialization takes the
default value from the struct instead of the value, it removes the
necessity for creating new types just to implement `Default` on them for
deserialization.

Additionally, the struct deserialization also checks for `Option` values
and makes sure that explicitly specifying `none` as text literal is
allowed for all options.

The other part of the derive macro is responsible for deserializing
enums. While only enums with Unit variants are supported, it will
automatically implement a deserializer for these enums which accepts any
form of capitalization.

Since this custom derive prevents us from using serde's attributes on
fields, some of the attributes have been reimplemented for
`ConfigDeserialize`. These include `#[config(flatten)]`,
`#[config(skip)]` and `#[config(alias = "alias)]`. The flatten attribute
is currently limited to at most one per struct.

Additionally the `#[config(deprecated = "optional message")]` attribute
allows easily defining uniform deprecation messages for fields on
structs.

1 files changed, 7 insertions, 9 deletions

diff --git a/alacritty/src/display.rs b/alacritty/src/display.rs
index 451874c8..1fe1d2de 100644
--- a/alacritty/src/display.rs
+++ b/alacritty/src/display.rs
@@ -20,8 +20,6 @@ use unicode_width::UnicodeWidthChar;
 #[cfg(all(feature = "wayland", not(any(target_os = "macos", windows))))]
 use wayland_client::{Display as WaylandDisplay, EventQueue};
 
-#[cfg(target_os = "macos")]
-use crossfont::set_font_smoothing;
 use crossfont::{self, Rasterize, Rasterizer};
 
 use alacritty_terminal::event::{EventListener, OnResize};
@@ -254,7 +252,7 @@ impl Display {
 
         // Set subpixel anti-aliasing.
         #[cfg(target_os = "macos")]
-        set_font_smoothing(config.ui_config.font.use_thin_strokes());
+        crossfont::set_font_smoothing(config.ui_config.font.use_thin_strokes);
 
         #[cfg(all(feature = "x11", not(any(target_os = "macos", windows))))]
         let is_x11 = event_loop.is_x11();
@@ -313,7 +311,7 @@ impl Display {
         config: &Config,
     ) -> Result<(GlyphCache, f32, f32), Error> {
         let font = config.ui_config.font.clone();
-        let rasterizer = Rasterizer::new(dpr as f32, config.ui_config.font.use_thin_strokes())?;
+        let rasterizer = Rasterizer::new(dpr as f32, config.ui_config.font.use_thin_strokes)?;
 
         // Initialize glyph cache.
         let glyph_cache = {
@@ -491,8 +489,8 @@ impl Display {
                             .map_or(false, |viewport_match| viewport_match.contains(&cell_point))
                     {
                         let colors = config.colors.search.focused_match;
-                        let match_fg = colors.foreground().color(cell.fg, cell.bg);
-                        cell.bg = colors.background().color(cell.fg, cell.bg);
+                        let match_fg = colors.foreground.color(cell.fg, cell.bg);
+                        cell.bg = colors.background.color(cell.fg, cell.bg);
                         cell.fg = match_fg;
                         cell.bg_alpha = 1.0;
                     }
@@ -558,8 +556,8 @@ impl Display {
             let y = size_info.cell_height().mul_add(start_line.0 as f32, size_info.padding_y());
 
             let color = match message.ty() {
-                MessageType::Error => config.colors.normal().red,
-                MessageType::Warning => config.colors.normal().yellow,
+                MessageType::Error => config.colors.normal.red,
+                MessageType::Warning => config.colors.normal.yellow,
             };
 
             let message_bar_rect =
@@ -680,7 +678,7 @@ impl Display {
 
         let timing = format!("{:.3} usec", self.meter.average());
         let fg = config.colors.primary.background;
-        let bg = config.colors.normal().red;
+        let bg = config.colors.normal.red;
 
         self.renderer.with_api(&config.ui_config, config.cursor, &size_info, |mut api| {
             api.render_string(glyph_cache, size_info.screen_lines() - 2, &timing[..], fg, Some(bg));