Fix inlay hints display reverting to settings value on theme change (#…

…22605)

Closes #4276

Release Notes:

- Fixed inlay hints that have been manually enabled disappearing when
theme selector is used.

crates/editor/src/inlay_hint_cache.rs

@@ -36,6 +36,7 @@ pub struct InlayHintCache {
     allowed_hint_kinds: HashSet<Option<InlayHintKind>>,
     version: usize,
     pub(super) enabled: bool,
+    enabled_in_settings: bool,
     update_tasks: HashMap<ExcerptId, TasksForRanges>,
     refresh_task: Option<Task<()>>,
     invalidate_debounce: Option<Duration>,
@@ -268,6 +269,7 @@ impl InlayHintCache {
         Self {
             allowed_hint_kinds: inlay_hint_settings.enabled_inlay_hint_kinds(),
             enabled: inlay_hint_settings.enabled,
+            enabled_in_settings: inlay_hint_settings.enabled,
             hints: HashMap::default(),
             update_tasks: HashMap::default(),
             refresh_task: None,
@@ -288,10 +290,21 @@ impl InlayHintCache {
         visible_hints: Vec<Inlay>,
         cx: &mut ViewContext<Editor>,
     ) -> ControlFlow<Option<InlaySplice>> {
+        let old_enabled = self.enabled;
+        // If the setting for inlay hints has changed, update `enabled`. This condition avoids inlay
+        // hint visibility changes when other settings change (such as theme).
+        //
+        // Another option might be to store whether the user has manually toggled inlay hint
+        // visibility, and prefer this. This could lead to confusion as it means inlay hint
+        // visibility would not change when updating the setting if they were ever toggled.
+        if new_hint_settings.enabled != self.enabled_in_settings {
+            self.enabled = new_hint_settings.enabled;
+        };
+        self.enabled_in_settings = new_hint_settings.enabled;
         self.invalidate_debounce = debounce_value(new_hint_settings.edit_debounce_ms);
         self.append_debounce = debounce_value(new_hint_settings.scroll_debounce_ms);
         let new_allowed_hint_kinds = new_hint_settings.enabled_inlay_hint_kinds();
-        match (self.enabled, new_hint_settings.enabled) {
+        match (old_enabled, self.enabled) {
             (false, false) => {
                 self.allowed_hint_kinds = new_allowed_hint_kinds;
                 ControlFlow::Break(None)
@@ -314,7 +327,6 @@ impl InlayHintCache {
                 }
             }
             (true, false) => {
-                self.enabled = new_hint_settings.enabled;
                 self.allowed_hint_kinds = new_allowed_hint_kinds;
                 if self.hints.is_empty() {
                     ControlFlow::Break(None)
@@ -327,7 +339,6 @@ impl InlayHintCache {
                 }
             }
             (false, true) => {
-                self.enabled = new_hint_settings.enabled;
                 self.allowed_hint_kinds = new_allowed_hint_kinds;
                 ControlFlow::Continue(())
             }