Display whether branch has been merged when deleting protected branch

app/assets/javascripts/branches/branches_delete_modal.js

@@ -7,6 +7,7 @@ class DeleteModal {
     this.$branchName = $('.js-branch-name', this.$modal);
     this.$confirmInput = $('.js-delete-branch-input', this.$modal);
     this.$deleteBtn = $('.js-delete-branch', this.$modal);
+    this.$notMerged = $('.js-not-merged', this.$modal);
     this.bindEvents();
   }
 
@@ -16,8 +17,10 @@ class DeleteModal {
   }
 
   setModalData(e) {
-    this.branchName = e.currentTarget.dataset.branchName || '';
-    this.deletePath = e.currentTarget.dataset.deletePath || '';
+    const branchData = e.currentTarget.dataset;
+    this.branchName = branchData.branchName || '';
+    this.deletePath = branchData.deletePath || '';
+    this.isMerged = !!branchData.isMerged;
     this.updateModal();
   }
 
@@ -30,6 +33,7 @@ class DeleteModal {
     this.$confirmInput.val('');
     this.$deleteBtn.attr('href', this.deletePath);
     this.$deleteBtn.attr('disabled', true);
+    this.$notMerged.toggleClass('hidden', this.isMerged);
   }
 }
 

app/views/projects/branches/_branch.html.haml

@@ -43,7 +43,8 @@
               data: { toggle: "modal",
                 target: "#modal-delete-branch",
                 delete_path: project_branch_path(@project, branch.name),
-                branch_name: branch.name } }
+                branch_name: branch.name,
+                is_merged: ("true" if @repository.merged_to_root_ref?(branch.name)) } }
               = icon("trash-o")
           - else
             %button{ class: "btn btn-remove remove-row js-ajax-loading-spinner has-tooltip disabled",

app/views/projects/branches/_delete_protected_modal.html.haml

@@ -6,13 +6,18 @@
         %h3.page-title
           Delete protected branch
           = surround "'", "'?" do
-            %span.js-branch-name>[branch name]
+            %span.js-branch-name.ref-name>[branch name]
 
       .modal-body
         %p
           You’re about to permanently delete the protected branch
           = succeed '.' do
-            %strong.js-branch-name [branch name]
+            %strong.js-branch-name.ref-name [branch name]
+        %p.js-not-merged
+          - default_branch = capture do
+            %span.ref-name= @repository.root_ref
+          = s_("Branches|This branch hasn’t been merged into %{default_branch}.").html_safe % { default_branch: default_branch }
+          = s_("Branches|To avoid data loss, consider merging this branch before deleting it.")
         %p
           Once you confirm and press
           = succeed ',' do

changelogs/unreleased/winh-protected-branch-modal-merged.yml

@@ -0,0 +1,5 @@
+---
+title: Display whether branch has been merged when deleting protected branch
+merge_request: 14220
+author:
+type: changed