1 files changed, 42 insertions, 3 deletions
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index f9dcfb3d9d..ed400b2ee9 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -20,6 +20,7 @@
 #include "nvim/eval/encode.h"
 #include "nvim/eval/funcs.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/typval_defs.h"
 #include "nvim/eval/userfunc.h"
 #include "nvim/eval/vars.h"
 #include "nvim/eval/window.h"
@@ -822,7 +823,7 @@ static char *ex_let_option(char *arg, typval_T *const tv, const bool is_const,
       if (curval.type == kOptValTypeNumber) {
         newval = NUMBER_OPTVAL(new_n);
       } else {
-        newval = BOOLEAN_OPTVAL(new_n == 0 ? kFalse : (new_n >= 1 ? kTrue : kNone));
+        newval = BOOLEAN_OPTVAL(TRISTATE_FROM_INT(new_n));
       }
     } else if (!hidden && is_string
                && curval.data.string.data != NULL && newval.data.string.data != NULL) {  // string
@@ -1875,8 +1876,7 @@ static OptVal tv_to_optval(typval_T *tv, const char *option, uint32_t flags, boo
         semsg(_("E521: Number required: &%s = '%s'"), option, tv->vval.v_string);
       }
     }
-    value = (flags & P_NUM) ? NUMBER_OPTVAL((OptInt)n)
-                            : BOOLEAN_OPTVAL(n == 0 ? kFalse : (n >= 1 ? kTrue : kNone));
+    value = (flags & P_NUM) ? NUMBER_OPTVAL((OptInt)n) : BOOLEAN_OPTVAL(TRISTATE_FROM_INT(n));
   } else if ((flags & P_STRING) || is_tty_option(option)) {
     // Avoid setting string option to a boolean or a special value.
     if (tv->v_type != VAR_BOOL && tv->v_type != VAR_SPECIAL) {
@@ -1897,6 +1897,45 @@ static OptVal tv_to_optval(typval_T *tv, const char *option, uint32_t flags, boo
   return value;
 }
 
+/// Convert an option value to typval.
+///
+/// @param[in]  value  Option value to convert.
+///
+/// @return  OptVal converted to typval.
+typval_T optval_as_tv(OptVal value)
+{
+  typval_T rettv = { .v_type = VAR_SPECIAL, .vval = { .v_special = kSpecialVarNull } };
+
+  switch (value.type) {
+  case kOptValTypeNil:
+    break;
+  case kOptValTypeBoolean:
+    switch (value.data.boolean) {
+    case kTrue:
+      rettv.v_type = VAR_BOOL;
+      rettv.vval.v_bool = kBoolVarTrue;
+      break;
+    case kFalse:
+      rettv.v_type = VAR_BOOL;
+      rettv.vval.v_bool = kBoolVarFalse;
+      break;
+    case kNone:
+      break;  // return v:null for None boolean value
+    }
+    break;
+  case kOptValTypeNumber:
+    rettv.v_type = VAR_NUMBER;
+    rettv.vval.v_number = value.data.number;
+    break;
+  case kOptValTypeString:
+    rettv.v_type = VAR_STRING;
+    rettv.vval.v_string = value.data.string.data;
+    break;
+  }
+
+  return rettv;
+}
+
 /// Set option "varname" to the value of "varp" for the current buffer/window.
 static void set_option_from_tv(const char *varname, typval_T *varp)
 {