infer parameter type when function in table

resolve #1332

Author: sumneko

changelog.md

@@ -93,6 +93,16 @@ server will generate `doc.json` and `doc.md` in `LOGPATH`.
       end
   end
   ```
+* `CHG` [#1332] infer parameter type when function in table
+  ```lua
+  ---@class A
+  ---@field f fun(x: string)
+
+  ---@type A
+  local t = {
+      f = function (x) end --> `x` is inferred as `string`
+  }
+  ```
 * `CHG` find reference: respect `includeDeclaration` (although I don't know how to turn off this option in VSCode)
 * `FIX` [#1567]
 * `FIX` [#1593]
@@ -107,6 +117,7 @@ server will generate `doc.json` and `doc.md` in `LOGPATH`.
 [#1153]: https://github.com./sumneko/lua-language-server/issues/1153
 [#1177]: https://github.com./sumneko/lua-language-server/issues/1177
 [#1202]: https://github.com./sumneko/lua-language-server/issues/1202
+[#1332]: https://github.com./sumneko/lua-language-server/issues/1332
 [#1458]: https://github.com./sumneko/lua-language-server/issues/1458
 [#1557]: https://github.com./sumneko/lua-language-server/issues/1557
 [#1558]: https://github.com./sumneko/lua-language-server/issues/1558

script/vm/compiler.lua

@@ -1108,6 +1108,12 @@ local compilerSwitch = util.switch()
                 end
             end
         end
+
+        -- { f = function (<?x?>) end }
+        if source.parent.type == 'tablefield'
+        or source.parent.type == 'tableindex' then
+            vm.setNode(source, vm.compileNode(source.parent))
+        end
     end)
     : case 'paren'
     : call(function (source)

test/type_inference/init.lua

@@ -3866,3 +3866,13 @@ local function f()
     end
 end
 ]]
+
+TEST 'string' [[
+---@class A
+---@field f fun(x: string)
+
+---@type A
+local t = {
+    f = function (<?x?>) end
+}
+]]