patch 8.2.0302: setting 'term' may cause error in TermChanged autocommand

Problem:    Setting 'term' may cause error in TermChanged autocommand.
Solution:   Use aucmd_prepbuf() to switch to the buffer where the autocommand
            is to be executed. (closes #5682)

Author: brammool

src/term.c

@@ -2071,21 +2071,24 @@ set_termname(char_u *term)
 	check_map_keycodes();	// check mappings for terminal codes used
 
 	{
-	    bufref_T	old_curbuf;
+	    buf_T	*buf;
+	    aco_save_T	aco;
 
 	    /*
 	     * Execute the TermChanged autocommands for each buffer that is
 	     * loaded.
 	     */
-	    set_bufref(&old_curbuf, curbuf);
-	    FOR_ALL_BUFFERS(curbuf)
+	    FOR_ALL_BUFFERS(buf)
 	    {
 		if (curbuf->b_ml.ml_mfp != NULL)
+		{
+		    aucmd_prepbuf(&aco, buf);
 		    apply_autocmds(EVENT_TERMCHANGED, NULL, NULL, FALSE,
 								      curbuf);
+		    // restore curwin/curbuf and a few other things
+		    aucmd_restbuf(&aco);
+		}
 	    }
-	    if (bufref_valid(&old_curbuf))
-		curbuf = old_curbuf.br_buf;
 	}
     }
 

src/testdir/test_autocmd.vim

@@ -2382,4 +2382,24 @@ func Test_FileChangedRO_winclose()
   augroup! FileChangedROTest
 endfunc
 
+func LogACmd()
+  call add(g:logged, line('$'))
+endfunc
+
+func Test_TermChanged()
+  enew!
+  tabnew
+  call setline(1, ['a', 'b', 'c', 'd'])
+  $
+  au TermChanged * call LogACmd()
+  let g:logged = []
+  let term_save = &term
+  set term=xterm
+  call assert_equal([1, 4], g:logged)
+
+  au! TermChanged
+  let &term = term_save
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    302,
 /**/
     301,
 /**/