foldcolumn: allow auto:X

Similar to signcolumn, allow foldcolumn to adapt itself to the number of
folds.

Regression:
vim supports a maximum fdc of 12, this limits it to 9.

1 files changed, 24 insertions, 1 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index 8181883426..df0033a203 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -618,7 +618,6 @@ void win_set_minimal_style(win_T *wp)
   wp->w_p_cuc = false;
   wp->w_p_spell = false;
   wp->w_p_list = false;
-  wp->w_p_fdc = 0;
 
   // Hide EOB region: use " " fillchar and cleared highlighting
   if (wp->w_p_fcs_chars.eob != ' ') {
@@ -642,6 +641,12 @@ void win_set_minimal_style(win_T *wp)
     wp->w_p_scl = (char_u *)xstrdup("auto");
   }
 
+  // foldcolumn: use 'auto'
+  if (wp->w_p_fdc[0] != '0') {
+    xfree(wp->w_p_fdc);
+    wp->w_p_fdc = (char_u *)xstrdup("0");
+  }
+
   // colorcolumn: cleared
   if (wp->w_p_cc != NULL && *wp->w_p_cc != NUL) {
     xfree(wp->w_p_cc);
@@ -689,6 +694,24 @@ void win_check_anchored_floats(win_T *win)
   }
 }
 
+/// Return the number of requested fold columns, based on current
+/// folds signs and on user configuration.
+int win_fdccol_count(win_T *wp)
+{
+  const char *fdc = (const char *)wp->w_p_fdc;
+
+  // auto:<NUM>
+  if (strncmp(fdc, "auto:", 5) == 0) {
+    int needed_fdccols;
+    needed_fdccols = getDeepestNesting(wp);
+    int maximum = fdc[5] - '0';
+    return MIN(maximum, needed_fdccols);
+  } else {
+    return fdc[0] - '0';
+  }
+}
+
+
 static void ui_ext_win_position(win_T *wp)
 {
   if (!wp->w_floating) {