Fix replacing optional fields

This fixes an issue with the default `SerdeReplace` implementation where
it would never recurse through options but always replace the entire
option with the new value.

Closes alacritty#7518.

alacritty/src/config/debug.rs

@@ -1,7 +1,5 @@
 use log::LevelFilter;
 
-use serde::Deserialize;
-
 use alacritty_config_derive::ConfigDeserialize;
 
 /// Debugging options.
@@ -47,17 +45,17 @@ impl Default for Debug {
 }
 
 /// The renderer configuration options.
-#[derive(Deserialize, Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(ConfigDeserialize, Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum RendererPreference {
     /// OpenGL 3.3 renderer.
-    #[serde(rename = "glsl3")]
+    #[config(rename = "glsl3")]
     Glsl3,
 
     /// GLES 2 renderer, with optional extensions like dual source blending.
-    #[serde(rename = "gles2")]
+    #[config(rename = "gles2")]
     Gles2,
 
     /// Pure GLES 2 renderer.
-    #[serde(rename = "gles2_pure")]
+    #[config(rename = "gles2_pure")]
     Gles2Pure,
 }

alacritty/src/config/ui_config.rs

@@ -1,9 +1,11 @@
 use std::cell::RefCell;
 use std::collections::HashMap;
+use std::error::Error;
 use std::fmt::{self, Formatter};
 use std::path::PathBuf;
 use std::rc::Rc;
 
+use alacritty_config::SerdeReplace;
 use alacritty_terminal::term::Config as TermConfig;
 use alacritty_terminal::tty::{Options as PtyOptions, Shell};
 use log::{error, warn};
@@ -656,6 +658,14 @@ impl From<Program> for Shell {
     }
 }
 
+impl SerdeReplace for Program {
+    fn replace(&mut self, value: toml::Value) -> Result<(), Box<dyn Error>> {
+        *self = Self::deserialize(value)?;
+
+        Ok(())
+    }
+}
+
 pub(crate) struct StringVisitor;
 impl<'de> serde::de::Visitor<'de> for StringVisitor {
     type Value = String;

alacritty_config/Cargo.toml

@@ -12,3 +12,8 @@ rust-version = "1.70.0"
 log = { version = "0.4.17", features = ["serde"] }
 serde = "1.0.163"
 toml = "0.8.2"
+winit = { version = "0.29.7", features = ["serde"] }
+
+[dev-dependencies]
+alacritty_config_derive = { path = "../alacritty_config_derive" }
+serde = { version = "1.0.163", features = ["derive"] }

alacritty_config/src/lib.rs

@@ -1,14 +1,17 @@
 use std::collections::HashMap;
 use std::error::Error;
+use std::path::PathBuf;
 
 use log::LevelFilter;
+use winit::platform::wayland::Theme;
 use serde::Deserialize;
 use toml::Value;
 
 pub trait SerdeReplace {
     fn replace(&mut self, value: Value) -> Result<(), Box<dyn Error>>;
 }
 
+#[macro_export]
 macro_rules! impl_replace {
     ($($ty:ty),*$(,)*) => {
         $(
@@ -29,7 +32,9 @@ impl_replace!(
     bool,
     char,
     String,
+    PathBuf,
     LevelFilter,
+    Theme,
 );
 
 fn replace_simple<'de, D>(data: &mut D, value: Value) -> Result<(), Box<dyn Error>>
@@ -47,9 +52,12 @@ impl<'de, T: Deserialize<'de>> SerdeReplace for Vec<T> {
     }
 }
 
-impl<'de, T: Deserialize<'de>> SerdeReplace for Option<T> {
+impl<'de, T: SerdeReplace + Deserialize<'de>> SerdeReplace for Option<T> {
     fn replace(&mut self, value: Value) -> Result<(), Box<dyn Error>> {
-        replace_simple(self, value)
+        match self {
+            Some(inner) => inner.replace(value),
+            None => replace_simple(self, value),
+        }
     }
 }
 
@@ -58,3 +66,30 @@ impl<'de, T: Deserialize<'de>> SerdeReplace for HashMap<String, T> {
         replace_simple(self, value)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate as alacritty_config;
+    use alacritty_config_derive::ConfigDeserialize;
+
+    #[test]
+    fn replace_option() {
+        #[derive(ConfigDeserialize, Default, PartialEq, Eq, Debug)]
+        struct ReplaceOption {
+            a: usize,
+            b: usize,
+        }
+
+        let mut subject: Option<ReplaceOption> = None;
+
+        let value: Value = toml::from_str("a=1").unwrap();
+        SerdeReplace::replace(&mut subject, value).unwrap();
+
+        let value: Value = toml::from_str("b=2").unwrap();
+        SerdeReplace::replace(&mut subject, value).unwrap();
+
+        assert_eq!(subject, Some(ReplaceOption { a: 1, b: 2 }));
+    }
+}

alacritty_config_derive/tests/config.rs

@@ -39,6 +39,7 @@ struct Test {
     enom_error: TestEnum,
     #[config(removed = "it's gone")]
     gone: bool,
+    option_struct: Option<Test4>,
 }
 
 impl Default for Test {
@@ -53,6 +54,7 @@ impl Default for Test {
             enom_big: TestEnum::default(),
             enom_error: TestEnum::default(),
             gone: false,
+            option_struct: None,
         }
     }
 }
@@ -76,6 +78,12 @@ struct Test3 {
 #[derive(SerdeReplace, Deserialize, Default, PartialEq, Eq, Debug)]
 struct NewType(usize);
 
+#[derive(ConfigDeserialize, Default)]
+struct Test4 {
+    a: usize,
+    b: usize,
+}
+
 #[test]
 fn config_deserialize() {
     let logger = unsafe {
@@ -198,3 +206,18 @@ fn replace_flatten() {
 
     assert_eq!(test.flatten.flatty, 7);
 }
+
+#[test]
+fn replace_option_multiple() {
+    let mut test = Test::default();
+
+    let value = toml::from_str("option_struct.a=1").unwrap();
+    test.replace(value).unwrap();
+
+    let value = toml::from_str("option_struct.b=2").unwrap();
+    test.replace(value).unwrap();
+
+    let option_struct = test.option_struct.as_ref().unwrap();
+    assert_eq!(option_struct.a, 1);
+    assert_eq!(option_struct.b, 2);
+}