Don't default publishDecorations to true on the server

If the client doesn't specify this explicitly, that very likely means it doesn't
know about it and so we shouldn't send decorations. In particular, the recent
change to this default caused decorations to be sent to emacs, resulting in a
lot of warning spam.

crates/ra_lsp_server/src/init.rs

@@ -1,32 +1,37 @@
 use serde::{Deserialize, Deserializer};
 
 /// Client provided initialization options
-#[derive(Deserialize, Clone, Copy, Debug)]
-#[serde(rename_all = "camelCase")]
+#[derive(Deserialize, Clone, Copy, Debug, PartialEq, Eq)]
+#[serde(rename_all = "camelCase", default)]
 pub struct InitializationOptions {
     /// Whether the client supports our custom highlighting publishing decorations.
     /// This is different to the highlightingOn setting, which is whether the user
     /// wants our custom highlighting to be used.
     ///
-    /// Defaults to `true`
-    #[serde(default = "bool_true", deserialize_with = "nullable_bool_true")]
+    /// Defaults to `false`
+    #[serde(deserialize_with = "nullable_bool_false")]
     pub publish_decorations: bool,
 
     /// Whether or not the workspace loaded notification should be sent
     ///
     /// Defaults to `true`
-    #[serde(default = "bool_true", deserialize_with = "nullable_bool_true")]
+    #[serde(deserialize_with = "nullable_bool_true")]
     pub show_workspace_loaded: bool,
 }
 
 impl Default for InitializationOptions {
     fn default() -> InitializationOptions {
-        InitializationOptions { publish_decorations: true, show_workspace_loaded: true }
+        InitializationOptions { publish_decorations: false, show_workspace_loaded: true }
     }
 }
 
-fn bool_true() -> bool {
-    true
+/// Deserializes a null value to a bool false by default
+fn nullable_bool_false<'de, D>(deserializer: D) -> Result<bool, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let opt = Option::deserialize(deserializer)?;
+    Ok(opt.unwrap_or(false))
 }
 
 /// Deserializes a null value to a bool true by default
@@ -37,3 +42,20 @@ where
     let opt = Option::deserialize(deserializer)?;
     Ok(opt.unwrap_or(true))
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn deserialize_init_options_defaults() {
+        // check that null == default for both fields
+        let default = InitializationOptions::default();
+        assert_eq!(default, serde_json::from_str(r#"{}"#).unwrap());
+        assert_eq!(
+            default,
+            serde_json::from_str(r#"{"publishDecorations":null, "showWorkspaceLoaded":null}"#)
+                .unwrap()
+        );
+    }
+}