Merge pull request LuaLS#3208 from DoubleThoughtTheProgrammer/large-unions

fix: large unions no longer erroneously fail to match later variants

Author: sumneko

changelog.md

@@ -8,6 +8,8 @@
 * `FIX` Prevent class methods from triggering missing-fields diagnostics
 * `ADD` missing locale
 * `FIX` updates the EmmyLuaCodeStyle submodule reference to a newer commit, ensuring compatibility with GCC 15
+* `FIX` large unions will no longer erroneously fail to match later variants
+* `ADD` Lua.type.maxUnionVariants which can be set to limit how many union variants are checked against
 
 ## 3.14.0
 `2025-4-7`

script/config/template.lua

@@ -401,6 +401,7 @@ local template = {
     ['Lua.language.completeAnnotation']     = Type.Boolean >> true,
     ['Lua.type.castNumberToInteger']        = Type.Boolean >> true,
     ['Lua.type.weakUnionCheck']             = Type.Boolean >> false,
+    ['Lua.type.maxUnionVariants']           = Type.Integer >> 0,
     ['Lua.type.weakNilCheck']               = Type.Boolean >> false,
     ['Lua.type.inferParamType']             = Type.Boolean >> false,
     ['Lua.type.checkTableShape']            = Type.Boolean >> false,

script/vm/type.lua

@@ -374,10 +374,11 @@ function vm.isSubType(uri, child, parent, mark, errs)
     elseif child.type == 'vm.node' then
         if config.get(uri, 'Lua.type.weakUnionCheck') then
             local hasKnownType = 0
+            local maxUnionVariants = config.get(uri, 'Lua.type.maxUnionVariants') or 0
             local i = 0
             for n in child:eachObject() do
                 i = i + 1
-                if i > 100 then
+                if maxUnionVariants > 0 and i > maxUnionVariants then
                     break
                 end
                 if vm.getNodeName(n) then
@@ -403,10 +404,11 @@ function vm.isSubType(uri, child, parent, mark, errs)
         else
             local weakNil = config.get(uri, 'Lua.type.weakNilCheck')
             local skipTable
+            local maxUnionVariants = config.get(uri, 'Lua.type.maxUnionVariants') or 0
             local i = 0
             for n in child:eachObject() do
                 i = i + 1
-                if i > 100 then
+                if maxUnionVariants > 0 and i > maxUnionVariants then
                     break
                 end
                 if skipTable == nil and n.type == "table" and parent.type == "vm.node" then -- skip table type check if child has class
@@ -473,10 +475,11 @@ function vm.isSubType(uri, child, parent, mark, errs)
         parent = global
     elseif parent.type == 'vm.node' then
         local hasKnownType = 0
+        local maxUnionVariants = config.get(uri, 'Lua.type.maxUnionVariants') or 0
         local i = 0
         for n in parent:eachObject() do
             i = i + 1
-            if i > 100 then
+            if maxUnionVariants > 0 and i > maxUnionVariants then
                 break
             end
             if vm.getNodeName(n) then