refactor(options): remove code for multitype options

Problem: It was decided on Matrix chat that multitype options won't be necessary for Neovim options, and that options should only have a single canonical type. Therefore the code for supporting multitype options is unnecessary.

Solution: Remove the additional code that's used to provide multitype option support.

4 files changed, 11 insertions, 88 deletions

diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index b9b5a055fb..012d23b567 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -843,11 +843,10 @@ static char *ex_let_option(char *arg, typval_T *const tv, const bool is_const,
     goto theend;
   }
 
-  // Don't assume current and new values are of the same type in order to future-proof the code for
-  // when an option can have multiple types.
-  const bool is_num = ((curval.type == kOptValTypeNumber || curval.type == kOptValTypeBoolean)
-                       && (newval.type == kOptValTypeNumber || newval.type == kOptValTypeBoolean));
-  const bool is_string = curval.type == kOptValTypeString && newval.type == kOptValTypeString;
+  // Current value and new value must have the same type.
+  assert(curval.type == newval.type);
+  const bool is_num = curval.type == kOptValTypeNumber || curval.type == kOptValTypeBoolean;
+  const bool is_string = curval.type == kOptValTypeString;
 
   if (op != NULL && *op != '=') {
     if (!hidden && is_num) {  // number or bool
@@ -1900,8 +1899,6 @@ static void getwinvar(typval_T *argvars, typval_T *rettv, int off)
 ///
 /// @return  Typval converted to OptVal. Must be freed by caller.
 ///          Returns NIL_OPTVAL for invalid option name.
-///
-/// TODO(famiu): Refactor this to support multitype options.
 static OptVal tv_to_optval(typval_T *tv, OptIndex opt_idx, const char *option, bool *error)
 {
   OptVal value = NIL_OPTVAL;
diff --git a/src/nvim/generators/gen_options.lua b/src/nvim/generators/gen_options.lua
index c79683dc00..0298381ece 100644
--- a/src/nvim/generators/gen_options.lua
+++ b/src/nvim/generators/gen_options.lua
@@ -314,21 +314,6 @@ end
 
 --- @param o vim.option_meta
 --- @return string
-local function get_type_flags(o)
-  local opt_types = (type(o.type) == 'table') and o.type or { o.type }
-  local type_flags = '0'
-  assert(type(opt_types) == 'table')
-
-  for _, opt_type in ipairs(opt_types) do
-    assert(type(opt_type) == 'string')
-    type_flags = ('%s | (1 << %s)'):format(type_flags, opt_type_enum(opt_type))
-  end
-
-  return type_flags
-end
-
---- @param o vim.option_meta
---- @return string
 local function get_scope_flags(o)
   local scope_flags = '0'
 
@@ -427,8 +412,8 @@ local function dump_option(i, o)
   if o.abbreviation then
     w('    .shortname=' .. cstr(o.abbreviation))
   end
+  w('    .type=' .. opt_type_enum(o.type))
   w('    .flags=' .. get_flags(o))
-  w('    .type_flags=' .. get_type_flags(o))
   w('    .scope_flags=' .. get_scope_flags(o))
   w('    .scope_idx=' .. get_scope_idx(o))
   if o.enable_if then
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 551ea0be20..593ac62172 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -3121,17 +3121,10 @@ bool optval_equal(OptVal o1, OptVal o2)
   UNREACHABLE;
 }
 
-/// Get type of option. Does not support multitype options.
+/// Get type of option.
 static OptValType option_get_type(const OptIndex opt_idx)
 {
-  assert(!option_is_multitype(opt_idx));
-
-  // If the option only supports a single type, it means that the index of the option's type flag
-  // corresponds to the value of the type enum. So get the index of the type flag using xctz() and
-  // use that as the option's type.
-  OptValType type = xctz(options[opt_idx].type_flags);
-  assert(type > kOptValTypeNil && type < kOptValTypeSize);
-  return type;
+  return options[opt_idx].type;
 }
 
 /// Create OptVal from var pointer.
@@ -3149,11 +3142,6 @@ OptVal optval_from_varp(OptIndex opt_idx, void *varp)
     return BOOLEAN_OPTVAL(curbufIsChanged());
   }
 
-  if (option_is_multitype(opt_idx)) {
-    // Multitype options are stored as OptVal.
-    return *(OptVal *)varp;
-  }
-
   OptValType type = option_get_type(opt_idx);
 
   switch (type) {
@@ -3264,33 +3252,6 @@ OptVal object_as_optval(Object o, bool *error)
   UNREACHABLE;
 }
 
-/// Get an allocated string containing a list of valid types for an option.
-/// For options with a singular type, it returns the name of the type. For options with multiple
-/// possible types, it returns a slash separated list of types. For example, if an option can be a
-/// number, boolean or string, the function returns "number/boolean/string"
-static char *option_get_valid_types(OptIndex opt_idx)
-{
-  StringBuilder str = KV_INITIAL_VALUE;
-  kv_resize(str, 32);
-
-  // Iterate through every valid option value type and check if the option supports that type
-  for (OptValType type = 0; type < kOptValTypeSize; type++) {
-    if (option_has_type(opt_idx, type)) {
-      const char *typename = optval_type_get_name(type);
-
-      if (str.size == 0) {
-        kv_concat(str, typename);
-      } else {
-        kv_printf(str, "/%s", typename);
-      }
-    }
-  }
-
-  // Ensure that the string is NUL-terminated.
-  kv_push(str, NUL);
-  return str.items;
-}
-
 /// Check if option is hidden.
 ///
 /// @param  opt_idx  Option index in options[] table.
@@ -3303,25 +3264,10 @@ bool is_option_hidden(OptIndex opt_idx)
          && options[opt_idx].var == &options[opt_idx].def_val.data;
 }
 
-/// Check if option is multitype (supports multiple types).
-static bool option_is_multitype(OptIndex opt_idx)
-{
-  const OptTypeFlags type_flags = get_option(opt_idx)->type_flags;
-  assert(type_flags != 0);
-  return !is_power_of_two(type_flags);
-}
-
 /// Check if option supports a specific type.
 bool option_has_type(OptIndex opt_idx, OptValType type)
 {
-  // Ensure that type flags variable can hold all types.
-  STATIC_ASSERT(kOptValTypeSize <= sizeof(OptTypeFlags) * 8,
-                "Option type_flags cannot fit all option types");
-  // Ensure that the type is valid before accessing type_flags.
-  assert(type > kOptValTypeNil && type < kOptValTypeSize);
-  // Bitshift 1 by the value of type to get the type's corresponding flag, and check if it's set in
-  // the type_flags bit field.
-  return get_option(opt_idx)->type_flags & (1 << type);
+  return options[opt_idx].type == type;
 }
 
 /// Check if option supports a specific scope.
@@ -3658,11 +3604,10 @@ static const char *validate_option_value(const OptIndex opt_idx, OptVal *newval,
     }
   } else if (!option_has_type(opt_idx, newval->type)) {
     char *rep = optval_to_cstr(*newval);
-    char *valid_types = option_get_valid_types(opt_idx);
+    const char *type_str = optval_type_get_name(opt->type);
     snprintf(errbuf, IOSIZE, _("Invalid value for option '%s': expected %s, got %s %s"),
-             opt->fullname, valid_types, optval_type_get_name(newval->type), rep);
+             opt->fullname, type_str, optval_type_get_name(newval->type), rep);
     xfree(rep);
-    xfree(valid_types);
     errmsg = errbuf;
   } else if (newval->type == kOptValTypeNumber) {
     // Validate and bound check num option values.
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index 832e03148a..2b51547004 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -54,9 +54,6 @@ typedef enum {
   kOptValTypeNumber,
   kOptValTypeString,
 } OptValType;
-/// Always update this whenever a new option type is added.
-#define kOptValTypeSize (kOptValTypeString + 1)
-typedef uint32_t OptTypeFlags;
 
 /// Scopes that an option can support.
 typedef enum {
@@ -99,7 +96,6 @@ typedef struct {
   int os_flags;
 
   /// Old value of the option.
-  /// TODO(famiu): Convert `os_oldval` and `os_newval` to `OptVal` to accommodate multitype options.
   OptValData os_oldval;
   /// New value of the option.
   OptValData os_newval;
@@ -173,7 +169,7 @@ typedef struct {
   char *fullname;                    ///< full option name
   char *shortname;                   ///< permissible abbreviation
   uint32_t flags;                    ///< see above
-  OptTypeFlags type_flags;           ///< option type flags, see OptValType
+  OptValType type;                   ///< option type
   OptScopeFlags scope_flags;         ///< option scope flags, see OptScope
   void *var;                         ///< global option: pointer to variable;
                                      ///< window-local option: NULL;