dose not infer as nil by t.field = nil

Author: sumneko

changelog.md

@@ -5,6 +5,7 @@
 * `CHG` diagnostic: `---@diagnostic disable: <ERR_NAME>` can suppress syntax errors
 * `CHG` completion: `completion.callSnippet` no longer generate parameter types
 * `CHG` hover: show `---@type {x: number, y: number}` as detail instead of `table`
+* `CHG` dose not infer as `nil` by `t.field = nil`
 * `FIX` [#1278](https://github.com/sumneko/lua-language-server/issues/1278)
 * `FIX` [#1288](https://github.com/sumneko/lua-language-server/issues/1288)
 

script/core/diagnostics/assign-type-mismatch.lua

@@ -64,16 +64,20 @@ return function (uri, callback)
                 return
             end
         end
-        --[[
-        ---@class A
-        local mt
-        ---@type X
-        mt._x = nil -- don't warn this
-        ]]
         if value.type == 'nil' then
+            --[[
+            ---@class A
+            local mt
+            ---@type X
+            mt._x = nil -- don't warn this
+            ]]
             if hasMarkType(source) then
                 return
             end
+            if source.type == 'setfield'
+            or source.type == 'setindex' then
+                return
+            end
         end
 
         local valueNode = vm.compileNode(value)

script/vm/compiler.lua

@@ -1387,7 +1387,7 @@ local compilerSwitch = util.switch()
                 if src.value then
                     if bindDocs(src) then
                         vm.setNode(source, vm.compileNode(src))
-                    else
+                    elseif src.value.type ~= 'nil' then
                         vm.setNode(source, vm.compileNode(src.value))
                         local node = vm.getNode(src)
                         if node then
@@ -1949,7 +1949,7 @@ local function compileByGlobal(source)
             vm.setNode(set, globalNode, true)
         end
         for _, set in ipairs(global:getSets(uri)) do
-            if set.value then
+            if set.value and set.value.type ~= 'nil' then
                 if not hasMarkDoc or guide.isLiteral(set.value) then
                     globalNode:merge(vm.compileNode(set.value))
                 end

test/diagnostics/type-check.lua

@@ -570,9 +570,9 @@ end
 ]]
 
 TEST [[
+---@class A
+---@field x number?
 local t = {}
-t.x = 1
-t.x = nil
 
 ---@return number
 function F()
@@ -688,5 +688,11 @@ local t
 t = a.x
 ]]
 
+TEST [[
+local mt = {}
+mt.x = 1
+mt.x = nil
+]]
+
 config.remove(nil, 'Lua.diagnostics.disable', 'unused-local')
 config.remove(nil, 'Lua.diagnostics.disable', 'undefined-global')

test/type_inference/init.lua

@@ -3381,3 +3381,13 @@ TEST '{ [string]: number, [true]: string, [1]: boolean, tag: integer }' [[
 ---@type {[string]: number, [true]: string, [1]: boolean, tag: integer}
 local <?t?>
 ]]
+
+TEST 'unknown' [[
+local mt = {}
+mt.<?x?> = nil
+]]
+
+TEST 'unknown' [[
+mt = {}
+mt.<?x?> = nil
+]]