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 #7518.

2 files changed, 39 insertions, 2 deletions

diff --git a/alacritty_config/Cargo.toml b/alacritty_config/Cargo.toml
index 985da0e3..28875c3b 100644
--- a/alacritty_config/Cargo.toml
+++ b/alacritty_config/Cargo.toml
@@ -12,3 +12,7 @@ rust-version = "1.70.0"
 log = { version = "0.4.17", features = ["serde"] }
 serde = "1.0.163"
 toml = "0.8.2"
+
+[dev-dependencies]
+alacritty_config_derive = { path = "../alacritty_config_derive" }
+serde = { version = "1.0.163", features = ["derive"] }
diff --git a/alacritty_config/src/lib.rs b/alacritty_config/src/lib.rs
index c5a43b87..81e43bb8 100644
--- a/alacritty_config/src/lib.rs
+++ b/alacritty_config/src/lib.rs
@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 use std::error::Error;
+use std::path::PathBuf;
 
 use log::LevelFilter;
 use serde::Deserialize;
@@ -9,6 +10,7 @@ pub trait SerdeReplace {
     fn replace(&mut self, value: Value) -> Result<(), Box<dyn Error>>;
 }
 
+#[macro_export]
 macro_rules! impl_replace {
     ($($ty:ty),*$(,)*) => {
         $(
@@ -29,6 +31,7 @@ impl_replace!(
     bool,
     char,
     String,
+    PathBuf,
     LevelFilter,
 );
 
@@ -47,9 +50,12 @@ 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 +64,30 @@ 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 }));
+    }
+}