merge_tools: preserve executable bit on resolve

CHANGELOG.md

@@ -88,6 +88,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 * On Windows, workspace paths (printed by `jj root`) no longer use UNC-style
   `\\?\` paths unless necessary.
 
+* `jj resolve` no longer removes the executable bit on resolved files when using
+  an external merge tool.
+
 ## [0.24.0] - 2024-12-04
 
 ### Release highlights

cli/src/merge_tools/external.rs

@@ -296,7 +296,12 @@ pub fn run_mergetool_external(
     let new_tree_value = match new_file_ids.into_resolved() {
         Ok(new_file_id) => Merge::normal(TreeValue::File {
             id: new_file_id.unwrap(),
-            executable: false,
+            executable: conflict
+                .to_executable_merge()
+                .as_ref()
+                .and_then(Merge::resolve_trivial)
+                .copied()
+                .unwrap_or_default(),
         }),
         Err(new_file_ids) => conflict.with_new_file_ids(&new_file_ids),
     };

cli/tests/test_resolve_command.rs

@@ -1012,21 +1012,20 @@ fn test_resolve_conflicts_with_executable() {
     );
     let editor_script = test_env.set_up_fake_editor();
 
-    // TODO: resolving the conflict in "file1" should produce an executable, but it
-    // currently doesn't
+    // Test resolving the conflict in "file1", which should produce an executable
     std::fs::write(&editor_script, b"write\nresolution1\n").unwrap();
     let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["resolve", "file1"]);
     insta::assert_snapshot!(stdout, @r#""#);
     insta::assert_snapshot!(stderr, @r#"
     Resolving conflicts in: file1
-    Working copy now at: znkkpsqq 1a12c872 conflict | (conflict) conflict
+    Working copy now at: znkkpsqq eb159d56 conflict | (conflict) conflict
     Parent commit      : mzvwutvl 08932848 a | a
     Parent commit      : yqosqzyt b69b3de6 b | b
     Added 0 files, modified 1 files, removed 0 files
     There are unresolved conflicts at these paths:
     file2    2-sided conflict including an executable
     New conflicts appeared in these commits:
-      znkkpsqq 1a12c872 conflict | (conflict) conflict
+      znkkpsqq eb159d56 conflict | (conflict) conflict
     To resolve the conflicts, start by updating to it:
       jj new znkkpsqq
     Then use `jj resolve`, or edit the conflict markers in the file directly.
@@ -1036,9 +1035,7 @@ fn test_resolve_conflicts_with_executable() {
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff", "--git"]), 
     @r##"
     diff --git a/file1 b/file1
-    old mode 100755
-    new mode 100644
-    index 0000000000..95cc18629d
+    index 0000000000..95cc18629d 100755
     --- a/file1
     +++ b/file1
     @@ -1,7 +1,1 @@
@@ -1056,22 +1053,21 @@ fn test_resolve_conflicts_with_executable() {
         @"file2    2-sided conflict including an executable"
     );
 
-    // TODO: resolving the conflict in "file2" should produce an executable, but it
-    // currently doesn't
+    // Test resolving the conflict in "file2", which should produce an executable
     test_env.jj_cmd_ok(&repo_path, &["undo"]);
     std::fs::write(&editor_script, b"write\nresolution2\n").unwrap();
     let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["resolve", "file2"]);
     insta::assert_snapshot!(stdout, @r#""#);
     insta::assert_snapshot!(stderr, @r#"
     Resolving conflicts in: file2
-    Working copy now at: znkkpsqq 5b6d14ea conflict | (conflict) conflict
+    Working copy now at: znkkpsqq 4dccbb3c conflict | (conflict) conflict
     Parent commit      : mzvwutvl 08932848 a | a
     Parent commit      : yqosqzyt b69b3de6 b | b
     Added 0 files, modified 1 files, removed 0 files
     There are unresolved conflicts at these paths:
     file1    2-sided conflict including an executable
     New conflicts appeared in these commits:
-      znkkpsqq 5b6d14ea conflict | (conflict) conflict
+      znkkpsqq 4dccbb3c conflict | (conflict) conflict
     To resolve the conflicts, start by updating to it:
       jj new znkkpsqq
     Then use `jj resolve`, or edit the conflict markers in the file directly.
@@ -1081,9 +1077,7 @@ fn test_resolve_conflicts_with_executable() {
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["diff", "--git"]), 
     @r##"
     diff --git a/file2 b/file2
-    old mode 100755
-    new mode 100644
-    index 0000000000..775f078581
+    index 0000000000..775f078581 100755
     --- a/file2
     +++ b/file2
     @@ -1,7 +1,1 @@