vim-patch:8.2.3900: it is not easy to use a script-local function for an option

Problem:    It is not easy to use a script-local function for an option.
Solution:   recognize s: and <SID> at the start of the expression. (Yegappan
            Lakshmanan, closes vim/vim#9401)

https://github.com/vim/vim/commit/8bb65f230d3025037f34021a72616038da0601ee

Omit duplicate docs in fold.txt: removed in a later runtime update.
Cherry-pick test_diffmode.vim changes from patch 8.2.1432.

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/src/nvim/testdir/test_normal.vim b/src/nvim/testdir/test_normal.vim
index 9c5cc51f79..7e8b8c5eef 100644
--- a/src/nvim/testdir/test_normal.vim
+++ b/src/nvim/testdir/test_normal.vim
@@ -255,6 +255,45 @@ func Test_normal_formatexpr_returns_nonzero()
   close!
 endfunc
 
+" Test for using a script-local function for 'formatexpr'
+func Test_formatexpr_scriptlocal_func()
+  func! s:Format()
+    let g:FormatArgs = [v:lnum, v:count]
+  endfunc
+  set formatexpr=s:Format()
+  call assert_equal(expand('<SID>') .. 'Format()', &formatexpr)
+  new | only
+  call setline(1, range(1, 40))
+  let g:FormatArgs = []
+  normal! 2GVjgq
+  call assert_equal([2, 2], g:FormatArgs)
+  bw!
+  set formatexpr=<SID>Format()
+  call assert_equal(expand('<SID>') .. 'Format()', &formatexpr)
+  new | only
+  call setline(1, range(1, 40))
+  let g:FormatArgs = []
+  normal! 4GVjgq
+  call assert_equal([4, 2], g:FormatArgs)
+  bw!
+  let &formatexpr = 's:Format()'
+  new | only
+  call setline(1, range(1, 40))
+  let g:FormatArgs = []
+  normal! 6GVjgq
+  call assert_equal([6, 2], g:FormatArgs)
+  bw!
+  let &formatexpr = '<SID>Format()'
+  new | only
+  call setline(1, range(1, 40))
+  let g:FormatArgs = []
+  normal! 8GVjgq
+  call assert_equal([8, 2], g:FormatArgs)
+  setlocal formatexpr=
+  delfunc s:Format
+  bw!
+endfunc
+
 " basic test for formatprg
 func Test_normal06_formatprg()
   " only test on non windows platform