Convert vim.NIL in client response item and itemDefaults to nil. Fixes #2212 (#2217)

Author: ErikReider

lua/cmp/source.lua

@@ -360,9 +360,13 @@ source.complete = function(self, ctx, callback)
         local old_offset = self.offset
         local old_entries = self.entries
 
+        response.itemDefaults = misc.ensure_nil(response.itemDefaults)
+
         self.status = source.SourceStatus.COMPLETED
         self.entries = {}
         for _, item in ipairs(response.items or response) do
+          item = misc.ensure_nil(item)
+
           if item.label then
             local e = entry.new(ctx, self, item, response.itemDefaults)
             if not e:is_invalid() then

lua/cmp/utils/misc.lua

@@ -120,6 +120,31 @@ misc.merge = function(tbl1, tbl2)
   end
 end
 
+---Replaces all vim.NIL values with nil recursively
+---@generic T
+---@param tbl T
+---@return T
+misc.ensure_nil = function(tbl)
+  local is_dict = type(tbl) == 'table' and (not islist(tbl) or vim.tbl_isempty(tbl))
+  if is_dict then
+    local new_tbl = {}
+    for k, v in pairs(tbl) do
+        if v ~= misc.none then
+          new_tbl[k] = misc.ensure_nil(v)
+        else
+          new_tbl[k] = nil
+        end
+    end
+    return new_tbl
+  end
+
+  if tbl == misc.none then
+    return nil
+  else
+    return tbl
+  end
+end
+
 ---Generate id for group name
 misc.id = setmetatable({
   group = {},

lua/cmp/utils/misc_spec.lua

@@ -87,4 +87,30 @@ describe('misc', function()
     })
     assert.are.equal(merged.a, nil)
   end)
+
+  it('ensure_nil', function()
+    local ensured
+    ensured = misc.ensure_nil({ a = {} })
+    assert.are.same(ensured, { a = {} })
+
+    ensured = misc.ensure_nil(nil)
+    assert.are.equal(ensured, nil)
+
+    ensured = misc.ensure_nil(1)
+    assert.are.equal(ensured, 1)
+
+    ensured = misc.ensure_nil({
+      a = {
+        a = 1,
+        b = nil,
+        c = misc.none,
+        d = false,
+        e = "",
+      },
+    })
+    assert.are.equal(ensured.a.a, 1)
+    assert.are.equal(ensured.a.b, nil)
+    assert.are.equal(ensured.a.c, nil)
+    assert.are.equal(ensured.a.e, "")
+  end)
 end)