--- a/mercurial/bookmarks.py	Fri Jan 12 11:15:41 2018 +0000
+++ b/mercurial/bookmarks.py	Fri Jan 05 22:28:06 2018 +0530
@@ -830,6 +830,7 @@
     cur = repo.changectx('.').node()
     newact = None
     changes = []
+    hiddenrevs = set()
     for mark in names:
         mark = checkformat(repo, mark)
         if newact is None:
@@ -839,10 +840,17 @@
             return
         tgt = cur
         if rev:
-            tgt = scmutil.revsingle(repo, rev).node()
+            repo = scmutil.unhidehashlikerevs(repo, [rev], 'nowarn')
+            ctx = scmutil.revsingle(repo, rev)
+            if ctx.hidden():
+                hiddenrevs.add(ctx.hex()[:12])
+            tgt = ctx.node()
         for bm in marks.checkconflict(mark, force, tgt):
             changes.append((bm, None))
         changes.append((mark, tgt))
+    if hiddenrevs:
+        repo.ui.warn(_("bookmarking hidden changeset %s\n") %
+                     ', '.join(hiddenrevs))
     marks.applychanges(repo, tr, changes)
     if not inactive and cur == marks[newact] and not rev:
         activate(repo, newact)

--- a/tests/test-directaccess.t	Fri Jan 12 11:15:41 2018 +0000
+++ b/tests/test-directaccess.t	Fri Jan 05 22:28:06 2018 +0530
@@ -186,3 +186,11 @@
   abort: hidden revision '2' was rewritten as: 2443a0e66469!
   (use --hidden to access hidden revisions)
   [255]
+
+Setting a bookmark will make that changeset unhidden, so this should come in end
+
+  $ hg bookmarks -r 28ad74 book
+  bookmarking hidden changeset 28ad74487de9
+
+  $ hg bookmarks
+     book                      2:28ad74487de9

--- a/tests/test-log.t	Fri Jan 12 11:15:41 2018 +0000
+++ b/tests/test-log.t	Fri Jan 05 22:28:06 2018 +0530
@@ -1851,6 +1851,7 @@
 bookmarks prevent a changeset being hidden
 
   $ hg bookmark --hidden -r 1 X
+  bookmarking hidden changeset a765632148dc
   $ hg log --template '{rev}:{node}\n'
   1:a765632148dc55d38c35c4f247c618701886cb2f
   0:9f758d63dcde62d547ebfb08e1e7ee96535f2b05
@@ -1859,6 +1860,7 @@
 divergent bookmarks are not hidden
 
   $ hg bookmark --hidden -r 1 X@foo
+  bookmarking hidden changeset a765632148dc
   $ hg log --template '{rev}:{node}\n'
   1:a765632148dc55d38c35c4f247c618701886cb2f
   0:9f758d63dcde62d547ebfb08e1e7ee96535f2b05

--- a/tests/test-obsolete.t	Fri Jan 12 11:15:41 2018 +0000
+++ b/tests/test-obsolete.t	Fri Jan 05 22:28:06 2018 +0530
@@ -1333,6 +1333,7 @@
   $ echo "hello" > b
   $ hg commit --amend -m "message"
   $ hg book bookb -r 13bedc178fce --hidden
+  bookmarking hidden changeset 13bedc178fce
   $ hg log -r 13bedc178fce
   4:13bedc178fce (draft *obsolete*) [ bookb] add b [rewritten using amend as 5:a9b1f8652753]
   $ hg book -d bookb

--- a/tests/test-rebase-obsolete.t	Fri Jan 12 11:15:41 2018 +0000
+++ b/tests/test-rebase-obsolete.t	Fri Jan 05 22:28:06 2018 +0530
@@ -1496,6 +1496,7 @@
   $ hg log -r .  # working dir is at rev 3 (successor of 2)
   3:be1832deae9a b (no-eol)
   $ hg book -r 2 mybook --hidden  # rev 2 has a bookmark on it now
+  bookmarking hidden changeset 1e9a3c00cbe9
   $ hg up 2 && hg log -r .  # working dir is at rev 2 again
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   2:1e9a3c00cbe9 b (rewritten using rebase as 3:be1832deae9a) (no-eol)