fix #1256

changelog.md

@@ -3,6 +3,7 @@
 ## 3.4.1
 * `NEW` settings:
   * `type.weakNilCheck`
+* `FIX` [#1256](https://github.com/sumneko/lua-language-server/issues/1256)
 * `FIX` [#1257](https://github.com/sumneko/lua-language-server/issues/1257)
 
 ## 3.4.0

script/vm/compiler.lua

@@ -1033,13 +1033,14 @@ local binarySwich = util.switch()
     : call(function (source)
         local node1 = vm.compileNode(source[1])
         local node2 = vm.compileNode(source[2])
-        local r1 = vm.testCondition(source[1])
+        local r1    = vm.testCondition(source[1])
         if r1 == true then
             vm.setNode(source, node2)
         elseif r1 == false then
             vm.setNode(source, node1)
         else
-            vm.setNode(source, node2)
+            local node = node1:copy():setFalsy():merge(node2)
+            vm.setNode(source, node)
         end
     end)
     : case 'or'
@@ -1052,9 +1053,8 @@ local binarySwich = util.switch()
         elseif r1 == false then
             vm.setNode(source, node2)
         else
-            vm.getNode(source):merge(node1)
-            vm.getNode(source):setTruthy()
-            vm.getNode(source):merge(node2)
+            local node = node1:copy():setTruthy():merge(node2)
+            vm.setNode(source, node)
         end
     end)
     : case '=='

script/vm/value.lua

@@ -22,24 +22,16 @@ function vm.testCondition(source)
             if n[1] == false then
                 hasFalse = true
             end
-        end
-        if n.type == 'global' and n.cate == 'type' then
-            if n.name == 'true' then
-                hasTrue = true
-            end
+        elseif n.type == 'global' and n.cate == 'type' then
             if n.name == 'false'
             or n.name == 'nil' then
                 hasFalse = true
+            else
+                hasTrue = true
             end
-        end
-        if n.type == 'nil' then
+        elseif n.type == 'nil' then
             hasFalse = true
-        end
-        if n.type == 'string'
-        or n.type == 'number'
-        or n.type == 'integer'
-        or n.type == 'table'
-        or n.type == 'function' then
+        elseif guide.isLiteral(n) then
             hasTrue = true
         end
     end

test/type_inference/init.lua

@@ -3250,3 +3250,23 @@ local function f() end
 for x, <?y?> in f do
 end
 ]]
+
+TEST 'number|nil' [[
+---@type table|nil
+local a
+
+---@type number|nil
+local b
+
+local <?c?> = a and b
+]]
+
+TEST 'number|table|nil' [[
+---@type table|nil
+local a
+
+---@type number|nil
+local b
+
+local <?c?> = a or b
+]]