vim-patch:8.1.1795: no syntax HL after splitting windows with :bufdo

Problem:    No syntax HL after splitting windows with :bufdo. (Yasuhiro
            Matsumoto)
Solution:   Trigger Syntax autocommands in buffers that are active.
            (closes vim/vim#4761)
c7f1e40021

src/nvim/buffer_defs.h

@@ -91,6 +91,7 @@ typedef struct {
 #define BF_READERR      0x40    // got errors while reading the file
 #define BF_DUMMY        0x80    // dummy buffer, only used internally
 #define BF_PRESERVED    0x100   // ":preserve" was used
+#define BF_SYN_SET      0x200   // 'syntax' option was set
 
 // Mask to check for flags that prevent normal writing
 #define BF_WRITE_MASK   (BF_NOTEDITED + BF_NEW + BF_READERR)

src/nvim/ex_cmds2.c

@@ -2058,6 +2058,10 @@ void ex_listdo(exarg_T *eap)
     // Don't do syntax HL autocommands.  Skipping the syntax file is a
     // great speed improvement.
     save_ei = au_event_disable(",Syntax");
+
+    FOR_ALL_BUFFERS(buf) {
+      buf->b_flags &= ~BF_SYN_SET;
+    }
   }
 
   if (eap->cmdidx == CMD_windo
@@ -2252,9 +2256,32 @@ void ex_listdo(exarg_T *eap)
   }
 
   if (save_ei != NULL) {
+    buf_T *bnext;
+    aco_save_T aco;
+
     au_event_restore(save_ei);
-    apply_autocmds(EVENT_SYNTAX, curbuf->b_p_syn,
-                   curbuf->b_fname, true, curbuf);
+
+    for (buf_T *buf = firstbuf; buf != NULL; buf = bnext) {
+      bnext = buf->b_next;
+      if (buf->b_nwindows > 0 && (buf->b_flags & BF_SYN_SET)) {
+        buf->b_flags &= ~BF_SYN_SET;
+
+        // buffer was opened while Syntax autocommands were disabled,
+        // need to trigger them now.
+        if (buf == curbuf) {
+          apply_autocmds(EVENT_SYNTAX, curbuf->b_p_syn,
+                         curbuf->b_fname, true, curbuf);
+        } else {
+          aucmd_prepbuf(&aco, buf);
+          apply_autocmds(EVENT_SYNTAX, buf->b_p_syn,
+                         buf->b_fname, true, buf);
+          aucmd_restbuf(&aco);
+        }
+
+        // start over, in case autocommands messed things up.
+        bnext = firstbuf;
+      }
+    }
   }
 }
 

src/nvim/option.c

@@ -3438,6 +3438,7 @@ ambw_end:
       // recursively, to avoid endless recurrence.
       apply_autocmds(EVENT_SYNTAX, curbuf->b_p_syn, curbuf->b_fname,
                      value_changed || syn_recursive == 1, curbuf);
+      curbuf->b_flags |= BF_SYN_SET;
       syn_recursive--;
     } else if (varp == &(curbuf->b_p_ft)) {
       // 'filetype' is set, trigger the FileType autocommand

src/nvim/testdir/test_syntax.vim

@@ -475,6 +475,40 @@ func Test_bg_detection()
   hi Normal ctermbg=NONE
 endfunc
 
+func Test_syntax_hangs()
+  if !has('reltime') || !has('float') || !has('syntax')
+    return
+  endif
+
+  " This pattern takes a long time to match, it should timeout.
+  new
+  call setline(1, ['aaa', repeat('abc ', 1000), 'ccc'])
+  let start = reltime()
+  set nolazyredraw redrawtime=101
+  syn match Error /\%#=1a*.*X\@<=b*/
+  redraw
+  let elapsed = reltimefloat(reltime(start))
+  call assert_true(elapsed > 0.1)
+  call assert_true(elapsed < 1.0)
+
+  " second time syntax HL is disabled
+  let start = reltime()
+  redraw
+  let elapsed = reltimefloat(reltime(start))
+  call assert_true(elapsed < 0.1)
+
+  " after CTRL-L the timeout flag is reset
+  let start = reltime()
+  exe "normal \<C-L>"
+  redraw
+  let elapsed = reltimefloat(reltime(start))
+  call assert_true(elapsed > 0.1)
+  call assert_true(elapsed < 1.0)
+
+  set redrawtime&
+  bwipe!
+endfunc
+
 func Test_synstack_synIDtrans()
   new
   setfiletype c
@@ -550,38 +584,42 @@ func Test_syn_wrong_z_one()
   bwipe!
 endfunc
 
-func Test_syntax_hangs()
-  if !has('reltime') || !has('float') || !has('syntax')
-    return
-  endif
+func Test_syntax_after_bufdo()
+  call writefile(['/* aaa comment */'], 'Xaaa.c')
+  call writefile(['/* bbb comment */'], 'Xbbb.c')
+  call writefile(['/* ccc comment */'], 'Xccc.c')
+  call writefile(['/* ddd comment */'], 'Xddd.c')
 
-  " This pattern takes a long time to match, it should timeout.
-  new
-  call setline(1, ['aaa', repeat('abc ', 1000), 'ccc'])
-  let start = reltime()
-  set nolazyredraw redrawtime=101
-  syn match Error /\%#=1a*.*X\@<=b*/
-  redraw
-  let elapsed = reltimefloat(reltime(start))
-  call assert_true(elapsed > 0.1)
-  call assert_true(elapsed < 1.0)
+  let bnr = bufnr('%')
+  new Xaaa.c
+  badd Xbbb.c
+  badd Xccc.c
+  badd Xddd.c
+  exe "bwipe " . bnr
+  let l = []
+  bufdo call add(l, bufnr('%'))
+  call assert_equal(4, len(l))
 
-  " second time syntax HL is disabled
-  let start = reltime()
-  redraw
-  let elapsed = reltimefloat(reltime(start))
-  call assert_true(elapsed < 0.1)
+  syntax on
 
-  " after CTRL-L the timeout flag is reset
-  let start = reltime()
-  exe "normal \<C-L>"
-  redraw
-  let elapsed = reltimefloat(reltime(start))
-  call assert_true(elapsed > 0.1)
-  call assert_true(elapsed < 1.0)
+  " This used to only enable syntax HL in the last buffer.
+  bufdo tab split
+  tabrewind
+  for tab in range(1, 4)
+    norm fm
+    call assert_equal(['cComment'], map(synstack(line("."), col(".")), 'synIDattr(v:val, "name")'))
+    tabnext
+  endfor
 
-  set redrawtime&
-  bwipe!
+  bwipe! Xaaa.c
+  bwipe! Xbbb.c
+  bwipe! Xccc.c
+  bwipe! Xddd.c
+  syntax off
+  call delete('Xaaa.c')
+  call delete('Xbbb.c')
+  call delete('Xccc.c')
+  call delete('Xddd.c')
 endfunc
 
 func Test_syntax_foldlevel()