'fillchars': fix defaults logic; handle ambiwidth=double #7986

Update tests.

5 files changed, 48 insertions, 41 deletions

diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 3254ddfbd7..1856384ffa 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -937,7 +937,7 @@ extern char_u *compiled_sys;
  * directory is not a local directory, globaldir is NULL. */
 EXTERN char_u   *globaldir INIT(= NULL);
 
-/* Characters from 'listchars' option */
+// 'listchars' characters. Defaults are overridden in set_chars_option().
 EXTERN int lcs_eol INIT(= '$');
 EXTERN int lcs_ext INIT(= NUL);
 EXTERN int lcs_prec INIT(= NUL);
@@ -948,7 +948,7 @@ EXTERN int lcs_tab2 INIT(= NUL);
 EXTERN int lcs_trail INIT(= NUL);
 EXTERN int lcs_conceal INIT(= ' ');
 
-/* Characters from 'fillchars' option */
+// 'fillchars' characters. Defaults are overridden in set_chars_option().
 EXTERN int fill_stl INIT(= ' ');
 EXTERN int fill_stlnc INIT(= ' ');
 EXTERN int fill_vert INIT(= 9474);  // │
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 2341371f65..eff436eb4d 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -3381,37 +3381,38 @@ skip:
   return NULL;    /* no error */
 }
 
-/*
- * Handle setting 'listchars' or 'fillchars'.
- * Returns error message, NULL if it's OK.
- */
+
+/// Handle setting 'listchars' or 'fillchars'.
+/// Assume monocell characters
+///
+/// @param varp either &p_lcs ('listchars') or &p_fcs ('fillchar')
+/// @return error message, NULL if it's OK.
 static char_u *set_chars_option(char_u **varp)
 {
   int round, i, len, entries;
   char_u      *p, *s;
   int c1, c2 = 0;
   struct charstab {
-    int     *cp;
-    char    *name;
+    int     *cp;    ///< char value
+    char    *name;  ///< char id
+    int     def;    ///< default value
   };
-  static struct charstab filltab[] =
-  {
-    {&fill_stl,     "stl"},
-    {&fill_stlnc,   "stlnc"},
-    {&fill_vert,    "vert"},
-    {&fill_fold,    "fold"},
-    {&fill_diff,    "diff"},
+  static struct charstab filltab[] = {
+    { &fill_stl,     "stl"  , ' '  },
+    { &fill_stlnc,   "stlnc", ' '  },
+    { &fill_vert,    "vert" , 9474 },  // │
+    { &fill_fold,    "fold" , 183  },  // ·
+    { &fill_diff,    "diff" , '-'  },
   };
-  static struct charstab lcstab[] =
-  {
-    {&lcs_eol,      "eol"},
-    {&lcs_ext,      "extends"},
-    {&lcs_nbsp,     "nbsp"},
-    {&lcs_prec,     "precedes"},
-    {&lcs_space,    "space"},
-    {&lcs_tab2,     "tab"},
-    {&lcs_trail,    "trail"},
-    {&lcs_conceal,  "conceal"},
+  static struct charstab lcstab[] = {
+    { &lcs_eol,      "eol",      NUL },
+    { &lcs_ext,      "extends",  NUL },
+    { &lcs_nbsp,     "nbsp",     NUL },
+    { &lcs_prec,     "precedes", NUL },
+    { &lcs_space,    "space",    NUL },
+    { &lcs_tab2,     "tab",      NUL },
+    { &lcs_trail,    "trail",    NUL },
+    { &lcs_conceal,  "conceal",  NUL },
   };
   struct charstab *tab;
 
@@ -3421,20 +3422,29 @@ static char_u *set_chars_option(char_u **varp)
   } else {
     tab = filltab;
     entries = ARRAY_SIZE(filltab);
+    if (*p_ambw == 'd') {
+      // XXX: If ambiwidth=double then "|" and "·" take 2 columns, which is
+      // forbidden (TUI limitation?). Set old defaults.
+      filltab[2].def = '|';
+      filltab[3].def = '-';
+    } else {
+      filltab[2].def = 9474;  // │
+      filltab[3].def = 183;   // ·
+    }
   }
 
-  /* first round: check for valid value, second round: assign values */
-  for (round = 0; round <= 1; ++round) {
+  // first round: check for valid value, second round: assign values
+  for (round = 0; round <= 1; round++) {
     if (round > 0) {
-      /* After checking that the value is valid: set defaults: space for
-       * 'fillchars', NUL for 'listchars' */
-      for (i = 0; i < entries; ++i)
-        if (tab[i].cp != NULL)
-          *(tab[i].cp) = (varp == &p_lcs ? NUL : ' ');
-      if (varp == &p_lcs)
+      // After checking that the value is valid: set defaults
+      for (i = 0; i < entries; i++) {
+        if (tab[i].cp != NULL) {
+          *(tab[i].cp) = tab[i].def;
+        }
+      }
+      if (varp == &p_lcs) {
         lcs_tab1 = NUL;
-      else
-        fill_diff = '-';
+      }
     }
     p = *varp;
     while (*p) {
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index e0df8eae07..34ff810410 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -812,7 +812,7 @@ return {
       vi_def=true,
       redraw={'all_windows'},
       varname='p_fcs',
-      defaults={if_true={vi="vert:│,fold:·"}}
+      defaults={if_true={vi=''}}
     },
     {
       full_name='fixendofline', abbreviation='fixeol',
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 0b79f8584f..b4cdbbd824 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -7088,11 +7088,7 @@ static int fillchar_status(int *attr, win_T *wp)
 static int fillchar_vsep(win_T *wp, int *attr)
 {
   *attr = win_hl_attr(wp, HLF_C);
-  if (*attr == 0 && fill_vert == ' ') {
-    return 9474;  // default: "│"
-  } else {
-    return fill_vert;
-  }
+  return fill_vert;
 }
 
 /*
diff --git a/src/nvim/testdir/setup.vim b/src/nvim/testdir/setup.vim
index 87cf1f6163..7d6dd0c7ce 100644
--- a/src/nvim/testdir/setup.vim
+++ b/src/nvim/testdir/setup.vim
@@ -6,6 +6,7 @@ set directory^=.
 set backspace=
 set nohidden smarttab noautoindent noautoread complete-=i noruler noshowcmd
 set listchars=eol:$
+set fillchars=vert:\|,fold:-
 " Prevent Nvim log from writing to stderr.
 let $NVIM_LOG_FILE = exists($NVIM_LOG_FILE) ? $NVIM_LOG_FILE : 'Xnvim.log'