patch 9.2.0412: channel: term_start() out_cb/err_cb no longer deliver raw chunks

Problem:  channel: term_start() out_cb/err_cb no longer deliver raw
          chunks (regression from patch 9.2.0224, breaks callers like
          vim-fugitive that parse multi-line output)
          (D. Ben Knoble, after v9.2.0224)
Solution: Remove the PTY-specific per-line splitting in
          may_invoke_callback() so RAW callbacks again receive the
          raw chunk as returned by read(), preserving embedded NL.
          If per-line handling is desired, the callback must split
          "msg" on NL and strip the trailing CR itself; document
          this behavior in term_start().  Replace
          Test_term_start_cb_per_line() with
          Test_term_start_cb_raw_chunk() to verify the raw-chunk
          contract.

fixes:  #20041
closes: #20045

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-Authored-By: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/channel.txt

@@ -1,4 +1,4 @@
-*channel.txt*	For Vim version 9.2.  Last change: 2026 Apr 15
+*channel.txt*	For Vim version 9.2.  Last change: 2026 Apr 28
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar

runtime/doc/terminal.txt

@@ -965,6 +965,20 @@ term_start({cmd} [, {options}])			*term_start()*
 		input and one output handle, with no separate handle for
 		stderr.
 
+		Note: term_start() always uses RAW mode for its callbacks.
+		"out_cb" and "err_cb" receive the raw chunk of data as read
+		from the OS.  A single callback invocation may contain
+		multiple lines separated by NL, and (for stdout via a pty)
+		each line may have a trailing CR from the line discipline
+		(ONLCR).  If per-line handling is desired, the callback must
+		split "msg" on NL and strip the trailing CR itself.
+		Example: >
+			func Handle(ch, msg)
+			  for line in split(a:msg, "\n")
+			    echom substitute(line, '\r$', '', '')
+			  endfor
+			endfunc
+<
 		There are extra options:
 		   "term_name"	     name to use for the buffer name, instead
 				     of the command name.

src/channel.c

@@ -3510,46 +3510,7 @@ may_invoke_callback(channel_T *channel, ch_part_T part)
 		// invoke the channel callback
 		ch_log(channel, "Invoking channel callback %s",
 						    (char *)callback->cb_name);
-#ifdef FEAT_TERMINAL
-		// For a terminal job in RAW mode (term_start()), split msg on
-		// NL and invoke the callback once per line with trailing CR
-		// stripped.  This ensures out_cb/err_cb receive one line at a
-		// time regardless of how much data arrives in a single read.
-		if (ch_mode == CH_MODE_RAW && msg != NULL
-			&& channel->ch_job != NULL
-			&& channel->ch_job->jv_tty_out != NULL)
-		{
-		    char_u *cp = msg;
-		    char_u *nl;
-
-		    while ((nl = vim_strchr(cp, NL)) != NULL)
-		    {
-			long_u len = (long_u)(nl - cp);
-
-			if (len > 0 && cp[len - 1] == CAR)
-			    --len;
-			argv[1].vval.v_string = vim_strnsave(cp, len);
-			if (argv[1].vval.v_string != NULL)
-			    invoke_callback(channel, callback, argv);
-			vim_free(argv[1].vval.v_string);
-			cp = nl + 1;
-		    }
-		    if (*cp != NUL)
-		    {
-			long_u len = STRLEN(cp);
-
-			if (len > 0 && cp[len - 1] == CAR)
-			    --len;
-			argv[1].vval.v_string = vim_strnsave(cp, len);
-			if (argv[1].vval.v_string != NULL)
-			    invoke_callback(channel, callback, argv);
-			vim_free(argv[1].vval.v_string);
-		    }
-		    argv[1].vval.v_string = msg;
-		}
-		else
-#endif
-		    invoke_callback(channel, callback, argv);
+		invoke_callback(channel, callback, argv);
 	    }
 	}
     }

src/testdir/test_channel.vim

@@ -2933,13 +2933,15 @@ func Test_error_callback_terminal()
   unlet! g:out g:error
 endfunc
 
-" Verify that term_start() with out_cb/err_cb delivers one line per callback
-" call (no embedded newlines, no trailing CR), matching the user's expectation.
-func Test_term_start_cb_per_line()
+" Verify that term_start() with out_cb/err_cb delivers data in RAW mode,
+" preserving embedded newlines in the raw chunk received from read().  If
+" per-line handling is desired, it is the callback's responsibility to split
+" on NL and strip the trailing CR.
+func Test_term_start_cb_raw_chunk()
   CheckUnix
   CheckFeature terminal
   let g:Ch_msgs = []
-  let script_file = 'Xterm_cb_per_line.sh'
+  let script_file = 'Xterm_cb_raw_chunk.sh'
   call writefile(["#!/bin/sh",
         \         "printf 'err:1\\nerr:2\\n' >&2",
         \         "printf 'out:3\\n'"], script_file, 'D')
@@ -2947,10 +2949,16 @@ func Test_term_start_cb_per_line()
   let ptybuf = term_start('./' .. script_file, {
         \ 'out_cb': {ch, msg -> add(g:Ch_msgs, msg)},
         \ 'err_cb': {ch, msg -> add(g:Ch_msgs, msg)}})
-  call WaitForAssert({-> assert_equal(3, len(g:Ch_msgs))}, 5000)
-  " Each line must arrive as a separate callback call with no embedded CR/NL.
-  call assert_equal(['err:1', 'err:2', 'out:3'], g:Ch_msgs)
+  " Wait until both the raw stderr chunk and a stdout chunk have arrived.
+  call WaitForAssert({-> assert_true(
+        \ index(g:Ch_msgs, "err:1\nerr:2\n") >= 0
+        \ && match(g:Ch_msgs, 'out:3') >= 0)}, 5000)
+  " stderr (via pipe) arrives as a single raw chunk with embedded NL,
+  " not split per line.  stdout (via PTY) is delivered, but its exact
+  " CR/LF shape depends on the PTY line discipline, so we only check that
+  " 'out:3' appears somewhere in the received chunks.
   call job_stop(term_getjob(ptybuf))
+  exe 'bwipe! ' .. ptybuf
   unlet g:Ch_msgs
 endfunc
 

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    412,
 /**/
     411,
 /**/