Merge branch 'master' into 34312-eslint-vue-plugin

* master: (78 commits)
  Use --left-right and --max-count for counting diverging commits
  API: get participants from merge_requests & issues
  Copy Mermaid graphs as GFM
  Rephrase paragraph about e2e tests in merge requests in docs
  Remove EE only sections from docs
  Update redis-rack to 2.0.4
  Refactor matchers for background migrations
  Add id to modal.vue to support data-toggle="modal"
  Allow local tests to use a modified Gitaly
  Fix specs
  Use computed prop in expand button
  Update check.md
  add deprecation and removal issue to docs
  Add status attribute to runner api entity
  Fix typos in a code comment
  Refactor RelativePositioning so that it can be used by other classes
  Backport 'Rebase' feature from EE to CE
  Just try to detect and assign once
  Fix custom name in branch creation for issue in Firefox
  Modify `LDAP::Person` to return username value based on attributes
  ...

1 files changed, 23 insertions, 8 deletions

diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index cd490aaa291..34b070dd375 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -116,8 +116,10 @@ module Gitlab
         new_content_sha || old_content_sha
       end
 
+      # Use #itself to check the value wrapped by a BatchLoader instance, rather
+      # than if the BatchLoader instance itself is falsey.
       def blob
-        new_blob || old_blob
+        new_blob&.itself || old_blob&.itself
       end
 
       attr_writer :highlighted_diff_lines
@@ -173,7 +175,7 @@ module Gitlab
       end
 
       def binary?
-        has_binary_notice? || old_blob&.binary? || new_blob&.binary?
+        has_binary_notice? || try_blobs(:binary?)
       end
 
       def text?
@@ -181,15 +183,15 @@ module Gitlab
       end
 
       def external_storage_error?
-        old_blob&.external_storage_error? || new_blob&.external_storage_error?
+        try_blobs(:external_storage_error?)
       end
 
       def stored_externally?
-        old_blob&.stored_externally? || new_blob&.stored_externally?
+        try_blobs(:stored_externally?)
       end
 
       def external_storage
-        old_blob&.external_storage || new_blob&.external_storage
+        try_blobs(:external_storage)
       end
 
       def content_changed?
@@ -204,15 +206,15 @@ module Gitlab
       end
 
       def size
-        [old_blob&.size, new_blob&.size].compact.sum
+        valid_blobs.map(&:size).sum
       end
 
       def raw_size
-        [old_blob&.raw_size, new_blob&.raw_size].compact.sum
+        valid_blobs.map(&:raw_size).sum
       end
 
       def raw_binary?
-        old_blob&.raw_binary? || new_blob&.raw_binary?
+        try_blobs(:raw_binary?)
       end
 
       def raw_text?
@@ -235,6 +237,19 @@ module Gitlab
 
       private
 
+      # The blob instances are instances of BatchLoader, which means calling
+      # &. directly on them won't work. Object#try also won't work, because Blob
+      # doesn't inherit from Object, but from BasicObject (via SimpleDelegator).
+      def try_blobs(meth)
+        old_blob&.itself&.public_send(meth) || new_blob&.itself&.public_send(meth)
+      end
+
+      # We can't use #compact for the same reason we can't use &., but calling
+      # #nil? explicitly does work because it is proxied to the blob itself.
+      def valid_blobs
+        [old_blob, new_blob].reject(&:nil?)
+      end
+
       def text_position_properties(line)
         { old_line: line.old_line, new_line: line.new_line }
       end