vim-patch:8.1.0046: loading a session file fails if 'winheight' is big

Problem:    Loading a session file fails if 'winheight' is a big number.
Solution:   Set 'minwinheight' to zero at first.  Don't give an error when
            setting 'minwinheight' while 'winheight' is a big number.
            Fix using vertical splits. Fix setting 'minwinwidth'.
            (closes vim/vim#2970)
https://github.com/vim/vim/commit/1c3c10492a291270fa89b3c8df11828792f927d3

3 files changed, 45 insertions, 14 deletions

diff --git a/src/nvim/option.c b/src/nvim/option.c
index 6eeeca5068..ed9128dbbf 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -4330,19 +4330,26 @@ static char *set_num_option(int opt_idx, char_u *varp, long value,
 
   // Number options that need some action when changed
   if (pp == &p_wh) {
+    // 'winheight'
     if (!ONE_WINDOW && curwin->w_height < p_wh) {
       win_setheight((int)p_wh);
     }
   } else if (pp == &p_hh) {
+    // 'helpheight'
     if (!ONE_WINDOW && curbuf->b_help && curwin->w_height < p_hh) {
       win_setheight((int)p_hh);
     }
   } else if (pp == &p_wmh) {
+    // 'winminheight'
     win_setminheight();
   } else if (pp == &p_wiw) {
+    // 'winwidth'
     if (!ONE_WINDOW && curwin->w_width < p_wiw) {
       win_setwidth((int)p_wiw);
     }
+  } else if (pp == &p_wmw) {
+    // 'winminwidth'
+    win_setminwidth();
   } else if (pp == &p_ls) {
     last_status(false);  // (re)set last window status line.
   } else if (pp == &p_stal) {
diff --git a/src/nvim/testdir/test_mksession.vim b/src/nvim/testdir/test_mksession.vim
index 0e56ed2ff3..b7169444d1 100644
--- a/src/nvim/testdir/test_mksession.vim
+++ b/src/nvim/testdir/test_mksession.vim
@@ -106,13 +106,22 @@ endfunc
 
 func Test_mksession_winheight()
   new
-  set winheight=10 winminheight=2
+  set winheight=10
+  set winminheight=2
   mksession! Xtest_mks.out
   source Xtest_mks.out
 
   call delete('Xtest_mks.out')
 endfunc
 
+func Test_mksession_large_winheight()
+  set winheight=999
+  mksession! Xtest_mks_winheight.out
+  set winheight&
+  source Xtest_mks_winheight.out
+  call delete('Xtest_mks_winheight.out')
+endfunc
+
 " Verify that arglist is stored correctly to the session file.
 func Test_mksession_arglist()
   argdel *
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 0e8cfcedf5..6861e19ca7 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5229,27 +5229,42 @@ static void frame_setwidth(frame_T *curfrp, int width)
   }
 }
 
-/*
- * Check 'winminheight' for a valid value.
- */
+// Check 'winminheight' for a valid value and reduce it if needed.
 void win_setminheight(void)
 {
-  int room;
-  int first = TRUE;
+  bool first = true;
 
-  /* loop until there is a 'winminheight' that is possible */
+  // loop until there is a 'winminheight' that is possible
   while (p_wmh > 0) {
-    /* TODO: handle vertical splits */
-    room = -p_wh;
-    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-      room += wp->w_height - p_wmh;
+    const int room = Rows - p_ch;
+    const int needed = frame_minheight(topframe, NULL);
+    if (room >= needed) {
+      break;
+    }
+    p_wmh--;
+    if (first) {
+      EMSG(_(e_noroom));
+      first = false;
     }
-    if (room >= 0)
+  }
+}
+
+// Check 'winminwidth' for a valid value and reduce it if needed.
+void win_setminwidth(void)
+{
+  bool first = true;
+
+  // loop until there is a 'winminheight' that is possible
+  while (p_wmw > 0) {
+    const int room = Columns;
+    const int needed = frame_minwidth(topframe, NULL);
+    if (room >= needed) {
       break;
-    --p_wmh;
+    }
+    p_wmw--;
     if (first) {
       EMSG(_(e_noroom));
-      first = FALSE;
+      first = false;
     }
   }
 }