patch 8.1.1676: "maxwidth" of popup window does not always work properly

Problem:    "maxwidth" of popup window does not always work properly.
Solution:   Adjust the computation. (Naruhiko Nishino, closes #4653)

src/popupwin.c

@@ -799,6 +799,8 @@ popup_height(win_T *wp)
     int
 popup_width(win_T *wp)
 {
+    // w_leftcol is how many columns of the core are left of the screen
+    // w_popup_rightoff is how many columns of the core are right of the screen
     return wp->w_width + wp->w_leftcol
 	+ wp->w_popup_padding[3] + wp->w_popup_border[3]
 	+ wp->w_popup_padding[1] + wp->w_popup_border[1]
@@ -924,7 +926,11 @@ popup_adjust_position(win_T *wp)
 	    wp->w_width = maxwidth;
 	}
 	if (wp->w_width < len)
+	{
 	    wp->w_width = len;
+	    if (wp->w_maxwidth > 0 && wp->w_width > wp->w_maxwidth)
+		wp->w_width = wp->w_maxwidth;
+	}
 	// do not use the width of lines we're not going to show
 	if (wp->w_maxheight > 0
 		       && lnum - wp->w_topline + 1 + wrapped > wp->w_maxheight)

src/testdir/dumps/Test_popupwin_menu_maxwidth_1.dump

@@ -0,0 +1,13 @@
+>╔+0#0000001#ffd7ff255|═@2|╗| +0#0000000#ffffff0@9|╔+0#0000001#ffd7ff255|═@11|╗| +0#0000000#ffffff0@2|╔+0#0000001#ffd7ff255|═@12|╗| +0#0000000#ffffff0@27
+|║+0#0000001#ffd7ff255| @2|║| +0#0000000#ffffff0@9|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0@2|║+0#0000001#ffd7ff255| @12|║| +0#0000000#ffffff0@27
+|║+0#0000001#ffd7ff255| |x+0&#e0e0e08| +0&#ffd7ff255|║| +0#0000000#ffffff0@9|║+0#0000001#ffd7ff255| |1+0&#e0e0e08|2|3|4|5|6|7|8|9||| +0&#ffd7ff255|║| +0#0000000#ffffff0@2|║+0#0000001#ffd7ff255| |1+0&#e0e0e08|2|3|4|5|6|7|8|9||| +0&#ffd7ff255| +0#0000000#0000001|║+0#0000001#ffd7ff255| +0#0000000#ffffff0@27
+|║+0#0000001#ffd7ff255| @2|║| +0#0000000#ffffff0@9|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0@2|║+0#0000001#ffd7ff255| |1|2|3|4|5|6|7|8|9||| | +0#0000000#0000001|║+0#0000001#ffd7ff255| +0#0000000#ffffff0@27
+|╚+0#0000001#ffd7ff255|═@2|╝| +0#0000000#ffffff0@9|╚+0#0000001#ffd7ff255|═@11|╝| +0#0000000#ffffff0@2|║+0#0000001#ffd7ff255| |1|2|3|4|5|6|7|8|9||| | +0#0000000#a8a8a8255|║+0#0000001#ffd7ff255| +0#0000000#ffffff0@27
+|6| @30|║+0#0000001#ffd7ff255| @12|║| +0#0000000#ffffff0@27
+|╔+0#0000001#ffd7ff255|═@11|╗| +0#0000000#ffffff0|╔+0#0000001#ffd7ff255|═@11|╗| +0#0000000#ffffff0@2|╚+0#0000001#ffd7ff255|═@12|╝| +0#0000000#ffffff0@27
+|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0@45
+|║+0#0000001#ffd7ff255| |1+0&#e0e0e08|2|3|4|5|6|7|8|9||| +0&#ffd7ff255|║| +0#0000000#ffffff0|║+0#0000001#ffd7ff255| |1+0&#e0e0e08|2|3|4|5|6|7|8|9||| +0&#ffd7ff255|║| +0#0000000#ffffff0@45
+|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0|║+0#0000001#ffd7ff255| @11|║| +0#0000000#ffffff0@45
+|╚+0#0000001#ffd7ff255|═@11|╝| +0#4040ff13#ffffff0|╚+0#0000001#ffd7ff255|═@11|╝| +0#4040ff13#ffffff0@45
+|~| @73
+| +0#0000000&@56|1|,|1| @10|A|l@1| 

src/testdir/test_popupwin.vim

@@ -1819,3 +1819,46 @@ func Test_popupwin_buf_close()
   call assert_equal([], bufinfo.popups)
   exe 'bwipe! ' .. buf
 endfunc
+
+func Test_popup_menu_with_maxwidth()
+  if !CanRunVimInTerminal()
+    throw 'Skipped: cannot make screendumps'
+  endif
+
+  let lines =<< trim END
+	call setline(1, range(1, 10))
+	hi ScrollThumb ctermbg=blue
+	hi ScrollBar ctermbg=red
+	func PopupMenu(lines, line, col, scrollbar = 0)
+		return popup_menu(a:lines, {
+			\ 'maxwidth': 10,
+			\ 'maxheight': 3,
+			\ 'pos' : 'topleft',
+			\ 'col' : a:col,
+			\ 'line' : a:line,
+			\ 'scrollbar' : a:scrollbar,
+			\ })
+	endfunc
+	call PopupMenu(['x'], 1, 1)
+	call PopupMenu(['123456789|'], 1, 16)
+	call PopupMenu(['123456789|' .. ' '], 7, 1)
+	call PopupMenu([repeat('123456789|', 100)], 7, 16)
+	call PopupMenu(repeat(['123456789|' .. ' '], 5), 1, 33, 1)
+  END
+  call writefile(lines, 'XtestPopupMenuMaxWidth')
+  let buf = RunVimInTerminal('-S XtestPopupMenuMaxWidth', {'rows': 13})
+  call VerifyScreenDump(buf, 'Test_popupwin_menu_maxwidth_1', {})
+
+  " close the menu popupwin.
+  call term_sendkeys(buf, " ")
+  call term_sendkeys(buf, " ")
+  call term_sendkeys(buf, " ")
+  call term_sendkeys(buf, " ")
+  call term_sendkeys(buf, " ")
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XtestPopupMenuMaxWidth')
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1676,
 /**/
     1675,
 /**/