vim-patch:9.0.0342: ":wincmd =" equalizes in two directions

Problem:    ":wincmd =" equalizes in two directions.
Solution:   Make ":vertical wincmd =" equalize vertically only and
            ":horizontal wincmd =" equalize horizontally only.
21c3a80a7f

runtime/doc/windows.txt

@@ -235,9 +235,16 @@ and 'winminwidth' are relevant.
 						*:vert* *:vertical*
 :vert[ical] {cmd}
 		Execute {cmd}.  If it contains a command that splits a window,
-		it will be split vertically.
+		it will be split vertically.  For `vertical wincmd =` windows
+		will be equialized only vertically.
 		Doesn't work for |:execute| and |:normal|.
 
+						*:hor* *:horizontal*
+:hor[izontal] {cmd}
+		Execute {cmd}.  Currently only makes a difference for
+		`horizontal wincmd =`, which will equal windows only
+		horizontally.
+
 :lefta[bove] {cmd}				*:lefta* *:leftabove*
 :abo[veleft] {cmd}				*:abo* *:aboveleft*
 		Execute {cmd}.  If it contains a command that splits a window,
@@ -530,6 +537,10 @@ CTRL-W =	Make all windows (almost) equally high and wide, but use
 		'winheight' and 'winwidth' for the current window.
 		Windows with 'winfixheight' set keep their height and windows
 		with 'winfixwidth' set keep their width.
+		To equalize only vertically (make window equally high) use
+		`vertical wincmd =`
+		To equalize only horizontally (make window equally wide) use
+		`horizontal wincmd =`
 
 :res[ize] -N					*:res* *:resize* *CTRL-W_-*
 CTRL-W -	Decrease current window height by N (default 1).

src/nvim/ex_cmds.lua

@@ -1140,6 +1140,12 @@ module.cmds = {
     addr_type='ADDR_NONE',
     func='ex_history',
   },
+  {
+    command='horizontal',
+    flags=bit.bor(NEEDARG, EXTRA, NOTRLCOM),
+    addr_type='ADDR_NONE',
+    func='ex_wrongmodifier',
+  },
   {
     command='insert',
     flags=bit.bor(BANG, RANGE, TRLBAR, CMDWIN, LOCK_OK, MODIFY),

src/nvim/ex_docmd.c

@@ -2438,8 +2438,12 @@ int parse_command_modifiers(exarg_T *eap, char **errormsg, cmdmod_T *cmod, bool
       continue;
     }
 
-    // ":hide" and ":hide | cmd" are not modifiers
     case 'h':
+      if (checkforcmd(&eap->cmd, "horizontal", 3)) {
+        cmod->cmod_split |= WSP_HOR;
+        continue;
+      }
+      // ":hide" and ":hide | cmd" are not modifiers
       if (p != eap->cmd || !checkforcmd(&p, "hide", 3)
           || *p == NUL || ends_excmd(*p)) {
         break;

src/nvim/testdir/test_window_cmd.vim

@@ -343,6 +343,46 @@ func Test_window_height()
   bw Xa Xb Xc
 endfunc
 
+func Test_wincmd_equal()
+  edit Xone
+  below split Xtwo
+  rightbelow vsplit Xthree
+  call assert_equal('Xone', bufname(winbufnr(1)))
+  call assert_equal('Xtwo', bufname(winbufnr(2)))
+  call assert_equal('Xthree', bufname(winbufnr(3)))
+
+  " Xone and Xtwo should be about the same height
+  let [wh1, wh2] = [winheight(1), winheight(2)]
+  call assert_inrange(wh1 - 1, wh1 + 1, wh2)
+  " Xtwo and Xthree should be about the same width
+  let [ww2, ww3] = [winwidth(2), winwidth(3)]
+  call assert_inrange(ww2 - 1, ww2 + 1, ww3)
+
+  1wincmd w
+  10wincmd _
+  2wincmd w
+  20wincmd |
+  call assert_equal(10, winheight(1))
+  call assert_equal(20, winwidth(2))
+
+  " equalizing horizontally doesn't change the heights
+  hor wincmd =
+  call assert_equal(10, winheight(1))
+  let [ww2, ww3] = [winwidth(2), winwidth(3)]
+  call assert_inrange(ww2 - 1, ww2 + 1, ww3)
+
+  2wincmd w
+  20wincmd |
+  call assert_equal(20, winwidth(2))
+  " equalizing vertically doesn't change the widths
+  vert wincmd =
+  call assert_equal(20, winwidth(2))
+  let [wh1, wh2] = [winheight(1), winheight(2)]
+  call assert_inrange(wh1 - 1, wh1 + 1, wh2)
+
+  bwipe Xone Xtwo Xthree
+endfunc
+
 func Test_window_width()
   e Xa
   vsplit Xb

src/nvim/window.c

@@ -417,10 +417,12 @@ newwindow:
               | ((nchar == 'H' || nchar == 'K') ? WSP_TOP : WSP_BOT));
     break;
 
-  // make all windows the same height
-  case '=':
-    win_equal(NULL, false, 'b');
+  // make all windows the same width and/or height
+  case '=': {
+    int mod = cmdmod.cmod_split & (WSP_VERT | WSP_HOR);
+    win_equal(NULL, false, mod == WSP_VERT ? 'v' : mod == WSP_HOR ? 'h' : 'b');
     break;
+  }
 
   // increase current window height
   case '+':

src/nvim/window.h

@@ -17,14 +17,15 @@
 #define FNAME_UNESC     32      // remove backslashes used for escaping
 
 // arguments for win_split()
-#define WSP_ROOM        1       // require enough room
-#define WSP_VERT        2       // split vertically
-#define WSP_TOP         4       // window at top-left of shell
-#define WSP_BOT         8       // window at bottom-right of shell
-#define WSP_HELP        16      // creating the help window
-#define WSP_BELOW       32      // put new window below/right
-#define WSP_ABOVE       64      // put new window above/left
-#define WSP_NEWLOC      128     // don't copy location list
+#define WSP_ROOM        0x01    // require enough room
+#define WSP_VERT        0x02    // split/equalize vertically
+#define WSP_HOR         0x04    // equalize horizontally
+#define WSP_TOP         0x08    // window at top-left of shell
+#define WSP_BOT         0x10    // window at bottom-right of shell
+#define WSP_HELP        0x20    // creating the help window
+#define WSP_BELOW       0x40    // put new window below/right
+#define WSP_ABOVE       0x80    // put new window above/left
+#define WSP_NEWLOC      0x100   // don't copy location list
 
 // Minimum screen size
 #define MIN_COLUMNS     12      // minimal columns for screen