14 files changed, 134 insertions, 9 deletions
diff --git a/3rd/lovr-api b/3rd/lovr-api
-Subproject 287070fc7e2e7b75407c4744c173497c89e1e51
+Subproject c148bfadad94144d423c6f9f7ce6033dfdc3779
diff --git a/changelog.md b/changelog.md
index d88c78ab..6446f811 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,9 @@
 # changelog
 
+## 3.4.1
+* `NEW` settings:
+  * `type.weakNilCheck`
+
 ## 3.4.0
 `2022-6-29`
 * `NEW` diagnostics:
diff --git a/doc/en-us/config.md b/doc/en-us/config.md
index 2a76be14..7317271d 100644
--- a/doc/en-us/config.md
+++ b/doc/en-us/config.md
@@ -1472,6 +1472,25 @@ boolean
 false
 ```
 
+# type.weakNilCheck
+
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+
+
+## type
+
+```ts
+boolean
+```
+
+## default
+
+```jsonc
+false
+```
+
 # type.weakUnionCheck
 
 Once one subtype of a union type meets the condition, the union type also meets the condition.
diff --git a/doc/pt-br/config.md b/doc/pt-br/config.md
index 55604b55..9cbefc2b 100644
--- a/doc/pt-br/config.md
+++ b/doc/pt-br/config.md
@@ -1472,6 +1472,25 @@ boolean
 false
 ```
 
+# type.weakNilCheck
+
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+
+
+## type
+
+```ts
+boolean
+```
+
+## default
+
+```jsonc
+false
+```
+
 # type.weakUnionCheck
 
 Once one subtype of a union type meets the condition, the union type also meets the condition.
diff --git a/doc/zh-cn/config.md b/doc/zh-cn/config.md
index 77f9b74d..cbf12bb1 100644
--- a/doc/zh-cn/config.md
+++ b/doc/zh-cn/config.md
@@ -1471,6 +1471,25 @@ boolean
 false
 ```
 
+# type.weakNilCheck
+
+对联合类型进行类型检查时，忽略其中的 `nil`。
+
+此设置为 `false` 时，`numer|nil` 类型无法赋给 `number` 类型；为 `true` 是则可以。
+
+
+## type
+
+```ts
+boolean
+```
+
+## default
+
+```jsonc
+false
+```
+
 # type.weakUnionCheck
 
 联合类型中只要有一个子类型满足条件，则联合类型也满足条件。
diff --git a/doc/zh-tw/config.md b/doc/zh-tw/config.md
index 62a76e57..6d0325b9 100644
--- a/doc/zh-tw/config.md
+++ b/doc/zh-tw/config.md
@@ -1471,6 +1471,25 @@ boolean
 false
 ```
 
+# type.weakNilCheck
+
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+
+
+## type
+
+```ts
+boolean
+```
+
+## default
+
+```jsonc
+false
+```
+
 # type.weakUnionCheck
 
 同位類型中只要有一個子類型滿足條件，則同位類型也滿足條件。
diff --git a/locale/en-us/setting.lua b/locale/en-us/setting.lua
index b2ba86fd..5ce69de7 100644
--- a/locale/en-us/setting.lua
+++ b/locale/en-us/setting.lua
@@ -275,6 +275,12 @@ Once one subtype of a union type meets the condition, the union type also meets
 
 When this setting is `false`, the `number|boolean` type cannot be assigned to the `number` type. It can be with `true`.
 ]]
+config.type.weakNilCheck                 =
+[[
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+]]
 config.diagnostics['unused-local']          =
 'Enable unused local variable diagnostics.'
 config.diagnostics['unused-function']       =
diff --git a/locale/pt-br/setting.lua b/locale/pt-br/setting.lua
index 3a8049af..e8271ce5 100644
--- a/locale/pt-br/setting.lua
+++ b/locale/pt-br/setting.lua
@@ -275,6 +275,12 @@ Once one subtype of a union type meets the condition, the union type also meets
 
 When this setting is `false`, the `number|boolean` type cannot be assigned to the `number` type. It can be with `true`.
 ]]
+config.type.weakNilCheck                 = -- TODO: need translate!
+[[
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+]]
 config.diagnostics['unused-local']          = -- TODO: need translate!
 '未使用的局部变量'
 config.diagnostics['unused-function']       = -- TODO: need translate!
diff --git a/locale/zh-cn/setting.lua b/locale/zh-cn/setting.lua
index 9fcd5e06..54de9293 100644
--- a/locale/zh-cn/setting.lua
+++ b/locale/zh-cn/setting.lua
@@ -274,6 +274,12 @@ config.type.weakUnionCheck               =
 
 此设置为 `false` 时，`number|boolean` 类型无法赋给 `number` 类型；为 `true` 时则可以。
 ]]
+config.type.weakNilCheck                 =
+[[
+对联合类型进行类型检查时，忽略其中的 `nil`。
+
+此设置为 `false` 时，`numer|nil` 类型无法赋给 `number` 类型；为 `true` 是则可以。
+]]
 config.diagnostics['unused-local']          =
 '未使用的局部变量'
 config.diagnostics['unused-function']       =
diff --git a/locale/zh-tw/setting.lua b/locale/zh-tw/setting.lua
index 3af50c5b..17a3435a 100644
--- a/locale/zh-tw/setting.lua
+++ b/locale/zh-tw/setting.lua
@@ -274,6 +274,12 @@ config.type.weakUnionCheck               =
 
 此設定為 `false` 時，`number|boolean` 類型無法賦給 `number` 類型；為 `true` 時則可以。
 ]]
+config.type.weakNilCheck                 = -- TODO: need translate!
+[[
+When checking the type of union type, ignore the `nil` in it.
+
+When this setting is `false`, the `number|nil` type cannot be assigned to the `number` type. It can be with `true`.
+]]
 config.diagnostics['unused-local']          =
 '未使用的區域變數'
 config.diagnostics['unused-function']       =
diff --git a/script/config/template.lua b/script/config/template.lua
index c7162012..3d5bad3d 100644
--- a/script/config/template.lua
+++ b/script/config/template.lua
@@ -366,6 +366,7 @@ local template = {
     ['Lua.misc.parameters']                 = Type.Array(Type.String),
     ['Lua.type.castNumberToInteger']        = Type.Boolean >> false,
     ['Lua.type.weakUnionCheck']             = Type.Boolean >> false,
+    ['Lua.type.weakNilCheck']               = Type.Boolean >> false,
 
     -- VSCode
     ['files.associations']                  = Type.Hash(Type.String, Type.String),
diff --git a/script/utility.lua b/script/utility.lua
index 034f19d5..e7aabaca 100644
--- a/script/utility.lua
+++ b/script/utility.lua
@@ -275,7 +275,7 @@ local function sortTable(tbl)
 end
 
 --- 创建一个有序表
----@param tbl table {optional = 'self'}
+---@param tbl? table
 ---@return table
 function m.container(tbl)
     return sortTable(tbl)
@@ -570,7 +570,7 @@ end
 ---遍历文本的每一行
 ---@param text string
 ---@param keepNL? boolean # 保留换行符
----@return fun(text:string):string, integer
+---@return fun():string, integer
 function m.eachLine(text, keepNL)
     local offset = 1
     local lineCount = 0
diff --git a/script/vm/type.lua b/script/vm/type.lua
index 399cbffc..ac3b8986 100644
--- a/script/vm/type.lua
+++ b/script/vm/type.lua
@@ -62,20 +62,18 @@ function vm.isSubType(uri, child, parent, mark)
                     return true
                 end
             end
-            if child:isOptional() then
-                if vm.isSubType(uri, 'nil', parent, mark) then
-                    return true
-                end
-            end
             return false
         else
+            local weakNil   = config.get(uri, 'Lua.type.weakNilCheck')
             for n in child:eachObject() do
-                if  getNodeName(n)
+                local nodeName = getNodeName(n)
+                if  nodeName
+                and not (nodeName == 'nil' and weakNil)
                 and not vm.isSubType(uri, n, parent, mark) then
                     return false
                 end
             end
-            if child:isOptional() then
+            if not weakNil and child:isOptional() then
                 if not vm.isSubType(uri, 'nil', parent, mark) then
                     return false
                 end
diff --git a/test/diagnostics/type-check.lua b/test/diagnostics/type-check.lua
index f4765370..32f60f82 100644
--- a/test/diagnostics/type-check.lua
+++ b/test/diagnostics/type-check.lua
@@ -609,5 +609,27 @@ local mt = G
 mt._x = nil
 ]]
 
+config.set(nil, 'Lua.type.weakNilCheck', true)
+TEST [[
+---@type number?
+local nb
+
+---@type number
+local n
+
+n = nb
+]]
+
+TEST [[
+---@type number|nil
+local nb
+
+---@type number
+local n
+
+n = nb
+]]
+config.set(nil, 'Lua.type.weakNilCheck', false)
+
 config.remove(nil, 'Lua.diagnostics.disable', 'unused-local')
 config.remove(nil, 'Lua.diagnostics.disable', 'undefined-global')