patch 8.1.2174: screen not recognized as supporting "sgr" mouse codes

Problem:    Screen not recognized as supporting "sgr" mouse codes.
Solution:   Recognize screen 4.7. (Jordan Christiansen, closes #5042)

src/term.c

@@ -4649,8 +4649,8 @@ check_termcode(
 		    if (tp[0] == CSI)
 			switch_to_8bit();
 
-		    // rxvt sends its version number: "20703" is 2.7.3.
 		    // Screen sends 40500.
+		    // rxvt sends its version number: "20703" is 2.7.3.
 		    // Ignore it for when the user has set 'term' to xterm,
 		    // even though it's an rxvt.
 		    if (version > 20000)
@@ -4661,6 +4661,7 @@ check_termcode(
 			int need_flush = FALSE;
 			int is_iterm2 = FALSE;
 			int is_mintty = FALSE;
+			int is_screen = FALSE;
 
 			// mintty 2.9.5 sends 77;20905;0c.
 			// (77 is ASCII 'M' for mintty.)
@@ -4706,14 +4707,21 @@ check_termcode(
 				is_not_xterm = TRUE;
 			}
 
+			// screen sends 83;40500;0 83 is 'S' in ASCII.
+			if (arg[0] == 83)
+			    is_screen = TRUE;
+
 			// Only set 'ttymouse' automatically if it was not set
 			// by the user already.
 			if (!option_was_set((char_u *)"ttym"))
 			{
 			    // Xterm version 277 supports SGR.  Also support
-			    // Terminal.app, iTerm2 and mintty.
-			    if (version >= 277 || is_iterm2 || is_mac_terminal
-				    || is_mintty)
+			    // Terminal.app, iTerm2, mintty, and screen 4.7+.
+			    if ((!is_screen && version >= 277)
+				    || is_iterm2
+				    || is_mac_terminal
+				    || is_mintty
+				    || (is_screen && arg[1] >= 40700))
 				set_option_value((char_u *)"ttym", 0L,
 							  (char_u *)"sgr", 0);
 			    // if xterm version >= 95 use mouse dragging

src/testdir/test_termcodes.vim

@@ -882,10 +882,35 @@ func Test_xx01_term_style_response()
   set t_RV=
 endfunc
 
+" This checks the iTerm2 version response.
+" This must be after other tests, because it has side effects to xterm
+" properties.
+func Test_xx02_iTerm2_response()
+  " Termresponse is only parsed when t_RV is not empty.
+  set t_RV=x
+
+  " Old versions of iTerm2 used a different style term response.
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>0;95;c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('xterm', &ttymouse)
+
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>0;95;0c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('sgr', &ttymouse)
+
+  set t_RV=
+endfunc
+
 " This checks the libvterm version response.
 " This must be after other tests, because it has side effects to xterm
 " properties.
-func Test_xx02_libvterm_response()
+func Test_xx03_libvterm_response()
   " Termresponse is only parsed when t_RV is not empty.
   set t_RV=x
 
@@ -899,10 +924,73 @@ func Test_xx02_libvterm_response()
   set t_RV=
 endfunc
 
+" This checks the Mac Terminal.app version response.
+" This must be after other tests, because it has side effects to xterm
+" properties.
+func Test_xx04_Mac_Terminal_response()
+  " Termresponse is only parsed when t_RV is not empty.
+  set t_RV=x
+
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>1;95;0c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('sgr', &ttymouse)
+
+  " Reset is_not_xterm and is_mac_terminal.
+  set t_RV=
+  set term=xterm
+  set t_RV=x
+endfunc
+
+" This checks the mintty version response.
+" This must be after other tests, because it has side effects to xterm
+" properties.
+func Test_xx05_mintty_response()
+  " Termresponse is only parsed when t_RV is not empty.
+  set t_RV=x
+
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>77;20905;0c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('sgr', &ttymouse)
+
+  set t_RV=
+endfunc
+
+" This checks the screen version response.
+" This must be after other tests, because it has side effects to xterm
+" properties.
+func Test_xx06_screen_response()
+  " Termresponse is only parsed when t_RV is not empty.
+  set t_RV=x
+
+  " Old versions of screen don't support SGR mouse mode.
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>83;40500;0c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('xterm', &ttymouse)
+
+  " screen supports SGR mouse mode starting in version 4.7.
+  set ttymouse=xterm
+  call test_option_not_set('ttymouse')
+  let seq = "\<Esc>[>83;40700;0c"
+  call feedkeys(seq, 'Lx!')
+  call assert_equal(seq, v:termresponse)
+  call assert_equal('sgr', &ttymouse)
+
+  set t_RV=
+endfunc
+
 " This checks the xterm version response.
 " This must be after other tests, because it has side effects to xterm
 " properties.
-func Test_xx03_xterm_response()
+func Test_xx07_xterm_response()
   " Termresponse is only parsed when t_RV is not empty.
   set t_RV=x
 
@@ -944,8 +1032,6 @@ func Test_xx03_xterm_response()
   set t_RV=
 endfunc
 
-" TODO: check other terminals response
-
 func Test_get_termcode()
   try
     let k1 = &t_k1

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2174,
 /**/
     2173,
 /**/