19 files changed, 322 insertions, 220 deletions

diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 0ee8134ec4..e355f82f4d 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -8,6 +8,7 @@
 #include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/extmark.h"
 #include "nvim/lua/executor.h"
 #include "nvim/memline.h"
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index b2d866ae0e..ebf4f65c91 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -22,6 +22,7 @@
 #include "nvim/charset.h"
 #include "nvim/context.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/edit.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index a850e5c1a0..dfcdfd8203 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -2428,9 +2428,8 @@ char *aucmd_exec_default_desc(AucmdExecutable acc)
   default:
     return NULL;
   }
-
-  abort();
 }
+
 char *aucmd_exec_to_string(AutoCmd *ac, AucmdExecutable acc)
 {
   switch (acc.type) {
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 97aac67627..3383dd2a76 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -928,10 +928,12 @@ void getvcol(win_T *wp, pos_T *pos, colnr_T *start, colnr_T *cursor, colnr_T *en
     // continue until the NUL
     posptr = NULL;
   } else {
-    // Special check for an empty line, which can happen on exit, when
-    // ml_get_buf() always returns an empty string.
-    if (*ptr == NUL) {
-      pos->col = 0;
+    // In a few cases the position can be beyond the end of the line.
+    for (colnr_T i = 0; i < pos->col; i++) {
+      if (ptr[i] == NUL) {
+        pos->col = i;
+        break;
+      }
     }
     posptr = ptr + pos->col;
     posptr -= utf_head_off(line, posptr);
diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index b533f4c46f..94bf1feeee 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -523,59 +523,6 @@ void decor_add_ephemeral(int start_row, int start_col, int end_row, int end_col,
 }
 
 
-DecorProvider *get_decor_provider(NS ns_id, bool force)
-{
-  size_t i;
-  size_t len = kv_size(decor_providers);
-  for (i = 0; i < len; i++) {
-    DecorProvider *item = &kv_A(decor_providers, i);
-    if (item->ns_id == ns_id) {
-      return item;
-    } else if (item->ns_id > ns_id) {
-      break;
-    }
-  }
-
-  if (!force) {
-    return NULL;
-  }
-
-  // Adding a new provider, so allocate room in the vector
-  (void)kv_a(decor_providers, len);
-  if (i < len) {
-    // New ns_id needs to be inserted between existing providers to maintain
-    // ordering, so shift other providers with larger ns_id
-    memmove(&kv_A(decor_providers, i + 1),
-            &kv_A(decor_providers, i),
-            (len - i) * sizeof(kv_a(decor_providers, i)));
-  }
-  DecorProvider *item = &kv_a(decor_providers, i);
-  *item = DECORATION_PROVIDER_INIT(ns_id);
-
-  return item;
-}
-
-void decor_provider_clear(DecorProvider *p)
-{
-  if (p == NULL) {
-    return;
-  }
-  NLUA_CLEAR_REF(p->redraw_start);
-  NLUA_CLEAR_REF(p->redraw_buf);
-  NLUA_CLEAR_REF(p->redraw_win);
-  NLUA_CLEAR_REF(p->redraw_line);
-  NLUA_CLEAR_REF(p->redraw_end);
-  p->active = false;
-}
-
-void decor_free_all_mem(void)
-{
-  for (size_t i = 0; i < kv_size(decor_providers); i++) {
-    decor_provider_clear(&kv_A(decor_providers, i));
-  }
-  kv_destroy(decor_providers);
-}
-
 
 int decor_virt_lines(win_T *wp, linenr_T lnum, VirtLines *lines)
 {
diff --git a/src/nvim/decoration.h b/src/nvim/decoration.h
index c186a1b1fd..8df53caa0a 100644
--- a/src/nvim/decoration.h
+++ b/src/nvim/decoration.h
@@ -82,26 +82,7 @@ typedef struct {
   int eol_col;
 } DecorState;
 
-typedef struct {
-  NS ns_id;
-  bool active;
-  LuaRef redraw_start;
-  LuaRef redraw_buf;
-  LuaRef redraw_win;
-  LuaRef redraw_line;
-  LuaRef redraw_end;
-  LuaRef hl_def;
-  int hl_valid;
-} DecorProvider;
-
-EXTERN kvec_t(DecorProvider) decor_providers INIT(= KV_INITIAL_VALUE);
 EXTERN DecorState decor_state INIT(= { 0 });
-EXTERN bool provider_active INIT(= false);
-
-#define DECORATION_PROVIDER_INIT(ns_id) (DecorProvider) \
-  { ns_id, false, LUA_NOREF, LUA_NOREF, \
-    LUA_NOREF, LUA_NOREF, LUA_NOREF, \
-    LUA_NOREF, -1 }
 
 static inline bool decor_has_sign(Decoration *decor)
 {
diff --git a/src/nvim/decoration_provider.c b/src/nvim/decoration_provider.c
new file mode 100644
index 0000000000..6efcb08b9d
--- /dev/null
+++ b/src/nvim/decoration_provider.c
@@ -0,0 +1,231 @@
+// This is an open source non-commercial project. Dear PVS-Studio, please check
+// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+
+#include "nvim/api/extmark.h"
+#include "nvim/api/private/helpers.h"
+#include "nvim/buffer.h"
+#include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
+#include "nvim/highlight.h"
+#include "nvim/lua/executor.h"
+
+static kvec_t(DecorProvider) decor_providers = KV_INITIAL_VALUE;
+
+#define DECORATION_PROVIDER_INIT(ns_id) (DecorProvider) \
+  { ns_id, false, LUA_NOREF, LUA_NOREF, \
+    LUA_NOREF, LUA_NOREF, LUA_NOREF, \
+    LUA_NOREF, -1 }
+
+static bool decor_provider_invoke(NS ns_id, const char *name, LuaRef ref,
+                                  Array args, bool default_true, char **perr)
+{
+  Error err = ERROR_INIT;
+
+  textlock++;
+  provider_active = true;
+  Object ret = nlua_call_ref(ref, name, args, true, &err);
+  provider_active = false;
+  textlock--;
+
+  if (!ERROR_SET(&err)
+      && api_object_to_bool(ret, "provider %s retval", default_true, &err)) {
+    return true;
+  }
+
+  if (ERROR_SET(&err)) {
+    const char *ns_name = describe_ns(ns_id);
+    ELOG("error in provider %s:%s: %s", ns_name, name, err.msg);
+    bool verbose_errs = true;  // TODO(bfredl):
+    if (verbose_errs && perr && *perr == NULL) {
+      static char errbuf[IOSIZE];
+      snprintf(errbuf, sizeof errbuf, "%s: %s", ns_name, err.msg);
+      *perr = xstrdup(errbuf);
+    }
+  }
+
+  api_free_object(ret);
+  return false;
+}
+
+/// For each provider invoke the 'start' callback
+///
+/// @param[out] providers Decoration providers
+/// @param[out] err       Provider err
+void decor_providers_start(DecorProviders *providers, int type, char **err)
+{
+  kvi_init(*providers);
+
+  for (size_t i = 0; i < kv_size(decor_providers); i++) {
+    DecorProvider *p = &kv_A(decor_providers, i);
+    if (!p->active) {
+      continue;
+    }
+
+    bool active;
+    if (p->redraw_start != LUA_NOREF) {
+      FIXED_TEMP_ARRAY(args, 2);
+      args.items[0] = INTEGER_OBJ((int)display_tick);
+      args.items[1] = INTEGER_OBJ(type);
+      active = decor_provider_invoke(p->ns_id, "start", p->redraw_start, args, true, err);
+    } else {
+      active = true;
+    }
+
+    if (active) {
+      kvi_push(*providers, p);
+    }
+  }
+}
+
+/// For each provider run 'win'. If result is not false, then collect the
+/// 'on_line' callback to call inside win_line
+///
+/// @param      wp             Window
+/// @param      providers      Decoration providers
+/// @param[out] line_providers Enabled line providers to invoke in win_line
+/// @param[out] err            Provider error
+void decor_providers_invoke_win(win_T *wp, DecorProviders *providers,
+                                DecorProviders *line_providers, char **err)
+{
+  kvi_init(*line_providers);
+
+  linenr_T knownmax = ((wp->w_valid & VALID_BOTLINE)
+                       ? wp->w_botline
+                       : (wp->w_topline + wp->w_height_inner));
+
+  for (size_t k = 0; k < kv_size(*providers); k++) {
+    DecorProvider *p = kv_A(*providers, k);
+    if (p && p->redraw_win != LUA_NOREF) {
+      FIXED_TEMP_ARRAY(args, 4);
+      args.items[0] = WINDOW_OBJ(wp->handle);
+      args.items[1] = BUFFER_OBJ(wp->w_buffer->handle);
+      // TODO(bfredl): we are not using this, but should be first drawn line?
+      args.items[2] = INTEGER_OBJ(wp->w_topline-1);
+      args.items[3] = INTEGER_OBJ(knownmax);
+      if (decor_provider_invoke(p->ns_id, "win", p->redraw_win, args, true, err)) {
+        kvi_push(*line_providers, p);
+      }
+    }
+  }
+
+  win_check_ns_hl(wp);
+}
+
+/// For each provider invoke the 'line' callback for a given window row.
+///
+/// @param      wp        Window
+/// @param      providers Decoration providers
+/// @param      row       Row to invoke line callback for
+/// @param[out] has_decor Set when at least one provider invokes a line callback
+/// @param[out] err       Provider error
+void providers_invoke_line(win_T *wp, DecorProviders *providers, int row, bool *has_decor,
+                           char **err)
+{
+  for (size_t k = 0; k < kv_size(*providers); k++) {
+    DecorProvider *p = kv_A(*providers, k);
+    if (p && p->redraw_line != LUA_NOREF) {
+      FIXED_TEMP_ARRAY(args, 3);
+      args.items[0] = WINDOW_OBJ(wp->handle);
+      args.items[1] = BUFFER_OBJ(wp->w_buffer->handle);
+      args.items[2] = INTEGER_OBJ(row);
+      if (decor_provider_invoke(p->ns_id, "line", p->redraw_line, args, true, err)) {
+        *has_decor = true;
+      } else {
+        // return 'false' or error: skip rest of this window
+        kv_A(*providers, k) = NULL;
+      }
+
+      win_check_ns_hl(wp);
+    }
+  }
+}
+
+
+/// For each provider invoke the 'buf' callback for a given buffer.
+///
+/// @param      buf       Buffer
+/// @param      providers Decoration providers
+/// @param[out] err       Provider error
+void decor_providers_invoke_buf(buf_T *buf, DecorProviders *providers, char **err)
+{
+  for (size_t i = 0; i < kv_size(*providers); i++) {
+    DecorProvider *p = kv_A(*providers, i);
+    if (p && p->redraw_buf != LUA_NOREF) {
+      FIXED_TEMP_ARRAY(args, 1);
+      args.items[0] = BUFFER_OBJ(buf->handle);
+      decor_provider_invoke(p->ns_id, "buf", p->redraw_buf, args, true, err);
+    }
+  }
+}
+
+
+/// For each provider invoke the 'end' callback
+///
+/// @param      providers   Decoration providers
+/// @param      displaytick Display tick
+/// @param[out] err         Provider error
+void decor_providers_invoke_end(DecorProviders *providers, char **err)
+{
+  for (size_t i = 0; i < kv_size(*providers); i++) {
+    DecorProvider *p = kv_A(*providers, i);
+    if (p && p->active && p->redraw_end != LUA_NOREF) {
+      FIXED_TEMP_ARRAY(args, 1);
+      args.items[0] = INTEGER_OBJ((int)display_tick);
+      decor_provider_invoke(p->ns_id, "end", p->redraw_end, args, true, err);
+    }
+  }
+}
+
+DecorProvider *get_decor_provider(NS ns_id, bool force)
+{
+  size_t i;
+  size_t len = kv_size(decor_providers);
+  for (i = 0; i < len; i++) {
+    DecorProvider *item = &kv_A(decor_providers, i);
+    if (item->ns_id == ns_id) {
+      return item;
+    } else if (item->ns_id > ns_id) {
+      break;
+    }
+  }
+
+  if (!force) {
+    return NULL;
+  }
+
+  // Adding a new provider, so allocate room in the vector
+  (void)kv_a(decor_providers, len);
+  if (i < len) {
+    // New ns_id needs to be inserted between existing providers to maintain
+    // ordering, so shift other providers with larger ns_id
+    memmove(&kv_A(decor_providers, i + 1),
+            &kv_A(decor_providers, i),
+            (len - i) * sizeof(kv_a(decor_providers, i)));
+  }
+  DecorProvider *item = &kv_a(decor_providers, i);
+  *item = DECORATION_PROVIDER_INIT(ns_id);
+
+  return item;
+}
+
+void decor_provider_clear(DecorProvider *p)
+{
+  if (p == NULL) {
+    return;
+  }
+  NLUA_CLEAR_REF(p->redraw_start);
+  NLUA_CLEAR_REF(p->redraw_buf);
+  NLUA_CLEAR_REF(p->redraw_win);
+  NLUA_CLEAR_REF(p->redraw_line);
+  NLUA_CLEAR_REF(p->redraw_end);
+  p->active = false;
+}
+
+void decor_free_all_mem(void)
+{
+  for (size_t i = 0; i < kv_size(decor_providers); i++) {
+    decor_provider_clear(&kv_A(decor_providers, i));
+  }
+  kv_destroy(decor_providers);
+}
+
diff --git a/src/nvim/decoration_provider.h b/src/nvim/decoration_provider.h
new file mode 100644
index 0000000000..3ec7c80357
--- /dev/null
+++ b/src/nvim/decoration_provider.h
@@ -0,0 +1,26 @@
+#ifndef NVIM_DECORATION_PROVIDER_H
+#define NVIM_DECORATION_PROVIDER_H
+
+#include "nvim/buffer_defs.h"
+
+typedef struct {
+  NS ns_id;
+  bool active;
+  LuaRef redraw_start;
+  LuaRef redraw_buf;
+  LuaRef redraw_win;
+  LuaRef redraw_line;
+  LuaRef redraw_end;
+  LuaRef hl_def;
+  int hl_valid;
+} DecorProvider;
+
+typedef kvec_withinit_t(DecorProvider *, 4) DecorProviders;
+
+EXTERN bool provider_active INIT(= false);
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "decoration_provider.h.generated.h"
+#endif
+
+#endif  // NVIM_DECORATION_PROVIDER_H
diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index 3aa9190db6..abbda1e9fa 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -5,6 +5,7 @@
 
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/highlight.h"
 #include "nvim/highlight_defs.h"
 #include "nvim/lua/executor.h"
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 7281809c06..a575aba50a 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -14,6 +14,7 @@
 #include "nvim/channel.h"
 #include "nvim/charset.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/eval.h"
 #include "nvim/ex_cmds.h"
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 8b29aa3676..b770fef05c 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -630,7 +630,7 @@ static char_u *mark_line(pos_T *mp, int lead_len)
   if (mp->lnum == 0 || mp->lnum > curbuf->b_ml.ml_line_count) {
     return vim_strsave((char_u *)"-invalid-");
   }
-  assert(Columns >= 0 && (size_t)Columns <= SIZE_MAX);
+  assert(Columns >= 0);
   // Allow for up to 5 bytes per character.
   s = vim_strnsave(skipwhite(ml_get(mp->lnum)), (size_t)Columns * 5);
 
diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index 677ff8f522..d68ca6b62e 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -10,7 +10,7 @@
 
 #include "nvim/api/extmark.h"
 #include "nvim/context.h"
-#include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/eval.h"
 #include "nvim/highlight.h"
 #include "nvim/lua/executor.h"
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 5c39e9c8bf..0e5e0ab403 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -3568,7 +3568,6 @@ static void nv_zet(cmdarg_T *cap)
   bool undo = false;
 
   int l_p_siso = (int)get_sidescrolloff_value(curwin);
-  assert(l_p_siso <= INT_MAX);
 
   if (ascii_isdigit(nchar)) {
     /*
diff --git a/src/nvim/option.c b/src/nvim/option.c
index a0706dfa14..191b635dc0 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -5664,12 +5664,10 @@ void comp_col(void)
     }
   }
   assert(sc_col >= 0
-         && INT_MIN + sc_col <= Columns
-         && Columns - sc_col <= INT_MAX);
+         && INT_MIN + sc_col <= Columns);
   sc_col = Columns - sc_col;
   assert(ru_col >= 0
-         && INT_MIN + ru_col <= Columns
-         && Columns - ru_col <= INT_MAX);
+         && INT_MIN + ru_col <= Columns);
   ru_col = Columns - ru_col;
   if (sc_col <= 0) {            // screen too narrow, will become a mess
     sc_col = 1;
diff --git a/src/nvim/popupmnu.c b/src/nvim/popupmnu.c
index d7726409b5..e354a589a5 100644
--- a/src/nvim/popupmnu.c
+++ b/src/nvim/popupmnu.c
@@ -289,8 +289,7 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
       if (pum_rl) {
         pum_width = pum_col - pum_scrollbar + 1;
       } else {
-        assert(Columns - pum_col - pum_scrollbar >= INT_MIN
-               && Columns - pum_col - pum_scrollbar <= INT_MAX);
+        assert(Columns - pum_col - pum_scrollbar >= 0);
         pum_width = Columns - pum_col - pum_scrollbar;
       }
 
@@ -356,7 +355,6 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
       } else {
         pum_col = 0;
       }
-      assert(Columns - 1 >= INT_MIN);
       pum_width = Columns - 1;
     } else {
       if (max_width > p_pw) {
@@ -367,8 +365,7 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
       if (pum_rl) {
         pum_col = max_width - 1;
       } else {
-        assert(Columns - max_width >= INT_MIN
-               && Columns - max_width <= INT_MAX);
+        assert(Columns - max_width >= 0);
         pum_col = Columns - max_width;
       }
       pum_width = max_width - pum_scrollbar;
diff --git a/src/nvim/regexp.c b/src/nvim/regexp.c
index 412cdac21b..009a26d4e0 100644
--- a/src/nvim/regexp.c
+++ b/src/nvim/regexp.c
@@ -1136,8 +1136,8 @@ static bool reg_match_visual(void)
     return false;
   }
 
+  col = (colnr_T)(rex.input - rex.line);
   if (mode == 'v') {
-    col = (colnr_T)(rex.input - rex.line);
     if ((lnum == top.lnum && col < top.col)
         || (lnum == bot.lnum && col >= bot.col + (*p_sel != 'e'))) {
       return false;
@@ -1152,8 +1152,12 @@ static bool reg_match_visual(void)
     if (top.col == MAXCOL || bot.col == MAXCOL || curswant == MAXCOL) {
       end = MAXCOL;
     }
-    unsigned int cols_u = win_linetabsize(wp, rex.line,
-                                          (colnr_T)(rex.input - rex.line));
+
+    // getvvcol() flushes rex.line, need to get it again
+    rex.line = reg_getline(rex.lnum);
+    rex.input = rex.line + col;
+
+    unsigned int cols_u = win_linetabsize(wp, rex.line, col);
     assert(cols_u <= MAXCOL);
     colnr_T cols = (colnr_T)cols_u;
     if (cols < start || cols > end - (*p_sel == 'e')) {
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index c8092c3503..0a1f388456 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -75,6 +75,7 @@
 #include "nvim/cursor.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/edit.h"
 #include "nvim/eval.h"
@@ -126,8 +127,6 @@
 #define MB_FILLER_CHAR '<'  /* character used when a double-width character
                              * doesn't fit. */
 
-typedef kvec_withinit_t(DecorProvider *, 4) Providers;
-
 // temporary buffer for rendering a single screenline, so it can be
 // compared with previous contents to calculate smallest delta.
 // Per-cell attributes
@@ -168,36 +167,6 @@ static bool resizing = false;
 
 static char *provider_err = NULL;
 
-static bool provider_invoke(NS ns_id, const char *name, LuaRef ref, Array args, bool default_true)
-{
-  Error err = ERROR_INIT;
-
-  textlock++;
-  provider_active = true;
-  Object ret = nlua_call_ref(ref, name, args, true, &err);
-  provider_active = false;
-  textlock--;
-
-  if (!ERROR_SET(&err)
-      && api_object_to_bool(ret, "provider %s retval", default_true, &err)) {
-    return true;
-  }
-
-  if (ERROR_SET(&err)) {
-    const char *ns_name = describe_ns(ns_id);
-    ELOG("error in provider %s:%s: %s", ns_name, name, err.msg);
-    bool verbose_errs = true;  // TODO(bfredl):
-    if (verbose_errs && provider_err == NULL) {
-      static char errbuf[IOSIZE];
-      snprintf(errbuf, sizeof errbuf, "%s: %s", ns_name, err.msg);
-      provider_err = xstrdup(errbuf);
-    }
-  }
-
-  api_free_object(ret);
-  return false;
-}
-
 /// Redraw a window later, with update_screen(type).
 ///
 /// Set must_redraw only if not already set to a higher value.
@@ -501,28 +470,8 @@ int update_screen(int type)
 
   ui_comp_set_screen_valid(true);
 
-  Providers providers;
-  kvi_init(providers);
-  for (size_t i = 0; i < kv_size(decor_providers); i++) {
-    DecorProvider *p = &kv_A(decor_providers, i);
-    if (!p->active) {
-      continue;
-    }
-
-    bool active;
-    if (p->redraw_start != LUA_NOREF) {
-      FIXED_TEMP_ARRAY(args, 2);
-      args.items[0] = INTEGER_OBJ(display_tick);
-      args.items[1] = INTEGER_OBJ(type);
-      active = provider_invoke(p->ns_id, "start", p->redraw_start, args, true);
-    } else {
-      active = true;
-    }
-
-    if (active) {
-      kvi_push(providers, p);
-    }
-  }
+  DecorProviders providers;
+  decor_providers_start(&providers, type, &provider_err);
 
   // "start" callback could have changed highlights for global elements
   if (win_check_ns_hl(NULL)) {
@@ -591,14 +540,7 @@ int update_screen(int type)
       }
 
       if (buf->b_mod_tick_decor < display_tick) {
-        for (size_t i = 0; i < kv_size(providers); i++) {
-          DecorProvider *p = kv_A(providers, i);
-          if (p && p->redraw_buf != LUA_NOREF) {
-            FIXED_TEMP_ARRAY(args, 1);
-            args.items[0] = BUFFER_OBJ(buf->handle);
-            provider_invoke(p->ns_id, "buf", p->redraw_buf, args, true);
-          }
-        }
+        decor_providers_invoke_buf(buf, &providers, &provider_err);
         buf->b_mod_tick_decor = display_tick;
       }
     }
@@ -668,18 +610,7 @@ int update_screen(int type)
   }
   did_intro = true;
 
-  for (size_t i = 0; i < kv_size(providers); i++) {
-    DecorProvider *p = kv_A(providers, i);
-    if (!p->active) {
-      continue;
-    }
-
-    if (p->redraw_end != LUA_NOREF) {
-      FIXED_TEMP_ARRAY(args, 1);
-      args.items[0] = INTEGER_OBJ(display_tick);
-      provider_invoke(p->ns_id, "end", p->redraw_end, args, true);
-    }
-  }
+  decor_providers_invoke_end(&providers, &provider_err);
   kvi_destroy(providers);
 
 
@@ -766,7 +697,7 @@ bool win_cursorline_standout(const win_T *wp)
  * mid: from mid_start to mid_end (update inversion or changed text)
  * bot: from bot_start to last row (when scrolled up)
  */
-static void win_update(win_T *wp, Providers *providers)
+static void win_update(win_T *wp, DecorProviders *providers)
 {
   buf_T *buf = wp->w_buffer;
   int type;
@@ -1377,30 +1308,8 @@ static void win_update(win_T *wp, Providers *providers)
 
   decor_redraw_reset(buf, &decor_state);
 
-  Providers line_providers;
-  kvi_init(line_providers);
-
-  linenr_T knownmax = ((wp->w_valid & VALID_BOTLINE)
-                       ? wp->w_botline
-                       : (wp->w_topline + wp->w_height_inner));
-
-  for (size_t k = 0; k < kv_size(*providers); k++) {
-    DecorProvider *p = kv_A(*providers, k);
-    if (p && p->redraw_win != LUA_NOREF) {
-      FIXED_TEMP_ARRAY(args, 4);
-      args.items[0] = WINDOW_OBJ(wp->handle);
-      args.items[1] = BUFFER_OBJ(buf->handle);
-      // TODO(bfredl): we are not using this, but should be first drawn line?
-      args.items[2] = INTEGER_OBJ(wp->w_topline-1);
-      args.items[3] = INTEGER_OBJ(knownmax);
-      if (provider_invoke(p->ns_id, "win", p->redraw_win, args, true)) {
-        kvi_push(line_providers, p);
-      }
-    }
-  }
-
-  win_check_ns_hl(wp);
-
+  DecorProviders line_providers;
+  decor_providers_invoke_win(wp, providers, &line_providers, &provider_err);
 
   for (;;) {
     /* stop updating when reached the end of the window (check for _past_
@@ -2028,6 +1937,17 @@ static size_t fill_foldcolumn(char_u *p, win_T *wp, foldinfo_T foldinfo, linenr_
   return MAX(char_counter + (fdc-i), (size_t)fdc);
 }
 
+static inline void provider_err_virt_text(linenr_T lnum, char *err)
+{
+  Decoration err_decor = DECORATION_INIT;
+  int hl_err = syn_check_group(S_LEN("ErrorMsg"));
+  kv_push(err_decor.virt_text,
+          ((VirtTextChunk){ .text = provider_err,
+                            .hl_id = hl_err }));
+  err_decor.virt_text_width = mb_string2cells((char_u *)err);
+  decor_add_ephemeral(lnum-1, 0, lnum-1, 0, &err_decor);
+}
+
 /// Display line "lnum" of window 'wp' on the screen.
 /// wp->w_virtcol needs to be valid.
 ///
@@ -2043,7 +1963,7 @@ static size_t fill_foldcolumn(char_u *p, win_T *wp, foldinfo_T foldinfo, linenr_
 ///
 /// @return             the number of last row the line occupies.
 static int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
-                    bool number_only, foldinfo_T foldinfo, Providers *providers)
+                    bool number_only, foldinfo_T foldinfo, DecorProviders *providers)
 {
   int c = 0;                          // init for GCC
   long vcol = 0;                      // virtual column (for tabs)
@@ -2231,34 +2151,12 @@ static int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool noc
 
     has_decor = decor_redraw_line(buf, lnum-1, &decor_state);
 
-    for (size_t k = 0; k < kv_size(*providers); k++) {
-      DecorProvider *p = kv_A(*providers, k);
-      if (p && p->redraw_line != LUA_NOREF) {
-        FIXED_TEMP_ARRAY(args, 3);
-        args.items[0] = WINDOW_OBJ(wp->handle);
-        args.items[1] = BUFFER_OBJ(buf->handle);
-        args.items[2] = INTEGER_OBJ(lnum-1);
-        if (provider_invoke(p->ns_id, "line", p->redraw_line, args, true)) {
-          has_decor = true;
-        } else {
-          // return 'false' or error: skip rest of this window
-          kv_A(*providers, k) = NULL;
-        }
-
-        win_check_ns_hl(wp);
-      }
-    }
+    providers_invoke_line(wp, providers, lnum-1, &has_decor, &provider_err);
 
     if (provider_err) {
-      Decoration err_decor = DECORATION_INIT;
-      int hl_err = syn_check_group(S_LEN("ErrorMsg"));
-      kv_push(err_decor.virt_text,
-              ((VirtTextChunk){ .text = provider_err,
-                                .hl_id = hl_err }));
-      err_decor.virt_text_width = mb_string2cells((char_u *)provider_err);
-      decor_add_ephemeral(lnum-1, 0, lnum-1, 0, &err_decor);
-      provider_err = NULL;
+      provider_err_virt_text(lnum, provider_err);
       has_decor = true;
+      provider_err = NULL;
     }
 
     if (has_decor) {
diff --git a/src/nvim/testdir/test_regexp_latin.vim b/src/nvim/testdir/test_regexp_latin.vim
index a92f7e1192..a0f5ebfb9f 100644
--- a/src/nvim/testdir/test_regexp_latin.vim
+++ b/src/nvim/testdir/test_regexp_latin.vim
@@ -795,4 +795,20 @@ func Test_using_mark_position()
   bwipe!
 endfunc
 
+func Test_using_visual_position()
+  " this was using freed memory
+  new
+  exe "norm 0o\<Esc>\<C-V>k\<C-X>o0"
+  /\%V
+  bwipe!
+endfunc
+
+func Test_using_invalid_visual_position()
+  " this was going beyond the end of the line
+  new
+  exe "norm 0o000\<Esc>0\<C-V>$s0"
+  /\%V
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 1ad82b7290..79a6b9ed0e 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -1475,8 +1475,8 @@ static void tui_guess_size(UI *ui)
   // 1 - look for non-default 'columns' and 'lines' options during startup
   if (data->is_starting && (Columns != DFLT_COLS || Rows != DFLT_ROWS)) {
     did_user_set_dimensions = true;
-    assert(Columns >= INT_MIN && Columns <= INT_MAX);
-    assert(Rows >= INT_MIN && Rows <= INT_MAX);
+    assert(Columns >= 0);
+    assert(Rows >= 0);
     width = Columns;
     height = Rows;
     goto end;