Color staged and unstaged hunks differently by opacity (#25108)

Release Notes:

- Make staged diff hunks appear as more opaque than unstaged hunks

---------

Co-authored-by: Nate Butler <iamnbutler@gmail.com>

crates/multi_buffer/src/multi_buffer.rs

@@ -9,6 +9,7 @@ pub use position::{TypedOffset, TypedPoint, TypedRow};
 use anyhow::{anyhow, Result};
 use buffer_diff::{
     BufferDiff, BufferDiffEvent, BufferDiffSnapshot, DiffHunkSecondaryStatus, DiffHunkStatus,
+    DiffHunkStatusKind,
 };
 use clock::ReplicaId;
 use collections::{BTreeMap, Bound, HashMap, HashSet};
@@ -135,12 +136,16 @@ pub struct MultiBufferDiffHunk {
 
 impl MultiBufferDiffHunk {
     pub fn status(&self) -> DiffHunkStatus {
-        if self.buffer_range.start == self.buffer_range.end {
-            DiffHunkStatus::Removed(self.secondary_status)
+        let kind = if self.buffer_range.start == self.buffer_range.end {
+            DiffHunkStatusKind::Deleted
         } else if self.diff_base_byte_range.is_empty() {
-            DiffHunkStatus::Added(self.secondary_status)
+            DiffHunkStatusKind::Added
         } else {
-            DiffHunkStatus::Modified(self.secondary_status)
+            DiffHunkStatusKind::Modified
+        };
+        DiffHunkStatus {
+            kind,
+            secondary: self.secondary_status,
         }
     }
 }
@@ -6210,7 +6215,7 @@ where
                     excerpt,
                     has_trailing_newline: *has_trailing_newline,
                     is_main_buffer: false,
-                    diff_hunk_status: Some(DiffHunkStatus::Removed(
+                    diff_hunk_status: Some(DiffHunkStatus::deleted(
                         hunk_info.hunk_secondary_status,
                     )),
                     buffer_range: buffer_start..buffer_end,
@@ -6256,7 +6261,7 @@ where
                     has_trailing_newline,
                     is_main_buffer: true,
                     diff_hunk_status: inserted_hunk_info
-                        .map(|info| DiffHunkStatus::Added(info.hunk_secondary_status)),
+                        .map(|info| DiffHunkStatus::added(info.hunk_secondary_status)),
                     buffer_range: buffer_start..buffer_end,
                     range: start..end,
                 })

crates/multi_buffer/src/multi_buffer_tests.rs

@@ -1,5 +1,5 @@
 use super::*;
-use buffer_diff::DiffHunkStatus;
+use buffer_diff::{DiffHunkStatus, DiffHunkStatusKind};
 use gpui::{App, TestAppContext};
 use indoc::indoc;
 use language::{Buffer, Rope};
@@ -1325,13 +1325,13 @@ fn test_basic_diff_hunks(cx: &mut TestAppContext) {
             .map(|info| (info.buffer_row, info.diff_status))
             .collect::<Vec<_>>(),
         vec![
-            (Some(0), Some(DiffHunkStatus::added())),
+            (Some(0), Some(DiffHunkStatus::added_none())),
             (Some(1), None),
-            (Some(1), Some(DiffHunkStatus::removed())),
-            (Some(2), Some(DiffHunkStatus::added())),
+            (Some(1), Some(DiffHunkStatus::deleted_none())),
+            (Some(2), Some(DiffHunkStatus::added_none())),
             (Some(3), None),
-            (Some(3), Some(DiffHunkStatus::removed())),
-            (Some(4), Some(DiffHunkStatus::removed())),
+            (Some(3), Some(DiffHunkStatus::deleted_none())),
+            (Some(4), Some(DiffHunkStatus::deleted_none())),
             (Some(4), None),
             (Some(5), None)
         ]
@@ -2279,7 +2279,7 @@ impl ReferenceMultibuffer {
                             buffer_start: Some(
                                 base_buffer.offset_to_point(hunk.diff_base_byte_range.start),
                             ),
-                            status: Some(DiffHunkStatus::Removed(hunk.secondary_status)),
+                            status: Some(DiffHunkStatus::deleted(hunk.secondary_status)),
                         });
                     }
 
@@ -2294,7 +2294,7 @@ impl ReferenceMultibuffer {
                         buffer_id: Some(buffer.remote_id()),
                         range: len..text.len(),
                         buffer_start: Some(buffer.offset_to_point(offset)),
-                        status: Some(DiffHunkStatus::Added(hunk.secondary_status)),
+                        status: Some(DiffHunkStatus::added(hunk.secondary_status)),
                     });
                     offset = hunk_range.end;
                 }
@@ -2664,13 +2664,13 @@ async fn test_random_multibuffer(cx: &mut TestAppContext, mut rng: StdRng) {
             snapshot.widest_line_number(),
             expected_row_infos
                 .into_iter()
-                .filter_map(
-                    |info| if matches!(info.diff_status, Some(DiffHunkStatus::Removed(_))) {
+                .filter_map(|info| {
+                    if info.diff_status.is_some_and(|status| status.is_deleted()) {
                         None
                     } else {
                         info.buffer_row
                     }
-                )
+                })
                 .max()
                 .unwrap()
                 + 1
@@ -3021,10 +3021,10 @@ fn format_diff(
         .enumerate()
         .zip(row_infos)
         .map(|((ix, line), info)| {
-            let marker = match info.diff_status {
-                Some(DiffHunkStatus::Added(_)) => "+ ",
-                Some(DiffHunkStatus::Removed(_)) => "- ",
-                Some(DiffHunkStatus::Modified(_)) => unreachable!(),
+            let marker = match info.diff_status.map(|status| status.kind) {
+                Some(DiffHunkStatusKind::Added) => "+ ",
+                Some(DiffHunkStatusKind::Deleted) => "- ",
+                Some(DiffHunkStatusKind::Modified) => unreachable!(),
                 None => {
                     if has_diff && !line.is_empty() {
                         "  "