Merge pull request #3330 from ian-pascoe:fix/generic-class-inheritance

fix: comprehensive generic type resolution improvements

Author: sumneko

changelog.md

@@ -3,6 +3,12 @@
 ## Unreleased
 <!-- Add all new changes here. They will be moved under a version at release -->
 * `FIX` convert all keys to string before using
+* `FIX` Generic class inheritance with type arguments now works correctly (e.g., `class Bar: Foo<integer>`) [#1929](https://github.com/LuaLS/lua-language-server/issues/1929)
+* `FIX` Method return types on generic classes now resolve correctly (e.g., `Box<string>:getValue()` returns `string`) [#1863](https://github.com/LuaLS/lua-language-server/issues/1863)
+* `FIX` Self-referential generic classes no longer cause infinite expansion in hover display [#1853](https://github.com/LuaLS/lua-language-server/issues/1853)
+* `FIX` Generic type parameters now work in `@overload` annotations [#723](https://github.com/LuaLS/lua-language-server/issues/723)
+* `NEW` Support `fun<T>` syntax for inline generic function types in `@field` and `@type` annotations [#1170](https://github.com/LuaLS/lua-language-server/issues/1170)
+* `FIX` Methods with `@generic T` and `@param self T` now correctly resolve return type to the receiver's concrete type (e.g., `List<number>:identity()` returns `List<number>`) [#1000](https://github.com/LuaLS/lua-language-server/issues/1000)
 
 ## 3.16.4
 `2025-12-25`

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

@@ -5,7 +5,8 @@ local vm    = require 'vm'
 local await = require 'await'
 
 ---@param defNode  vm.node
-local function expandGenerics(defNode)
+---@param classGenericMap table<string, vm.node>?
+local function expandGenerics(defNode, classGenericMap)
     ---@type parser.object[]
     local generics = {}
     for dn in defNode:eachObject() do
@@ -20,27 +21,78 @@ local function expandGenerics(defNode)
     end
 
     for _, generic in ipairs(generics) do
-        local limits = generic.generic and generic.generic.extends
-        if limits then
-            defNode:merge(vm.compileNode(limits))
+        -- First check if this generic is a class generic that can be resolved
+        local genericName = generic[1]
+        if classGenericMap and genericName and classGenericMap[genericName] then
+            defNode:merge(classGenericMap[genericName])
         else
-            local unknownType = vm.declareGlobal('type', 'unknown')
-            defNode:merge(unknownType)
+            -- Fall back to constraint or unknown
+            local limits = generic.generic and generic.generic.extends
+            if limits then
+                defNode:merge(vm.compileNode(limits))
+            else
+                local unknownType = vm.declareGlobal('type', 'unknown')
+                defNode:merge(unknownType)
+            end
+        end
+    end
+end
+
+---@param uri uri
+---@param source parser.object
+---@return table<string, vm.node>?
+local function getReceiverGenericMap(uri, source)
+    local callNode = source.node
+    if not callNode then
+        return nil
+    end
+    -- Only resolve generics for method calls (obj:method()), not static calls (Class.method())
+    if callNode.type ~= 'getmethod' then
+        return nil
+    end
+    local receiver = callNode.node
+    if not receiver then
+        return nil
+    end
+    local receiverNode = vm.compileNode(receiver)
+    for rn in receiverNode:eachObject() do
+        if rn.type == 'doc.type.sign' and rn.signs and rn.node and rn.node[1] then
+            local classGlobal = vm.getGlobal('type', rn.node[1])
+            if classGlobal then
+                return vm.getClassGenericMap(uri, classGlobal, rn.signs)
+            end
         end
     end
+    return nil
 end
 
 ---@param funcNode vm.node
 ---@param i integer
+---@param classGenericMap table<string, vm.node>?
 ---@return vm.node?
-local function getDefNode(funcNode, i)
+local function getDefNode(funcNode, i, classGenericMap)
     local defNode = vm.createNode()
     for src in funcNode:eachObject() do
         if src.type == 'function'
         or src.type == 'doc.type.function' then
             local param = src.args and src.args[i]
             if param then
-                defNode:merge(vm.compileNode(param))
+                local paramNode = vm.compileNode(param)
+                -- Check for global type references that match class generic params
+                if classGenericMap then
+                    local newNode = vm.createNode()
+                    for pn in paramNode:eachObject() do
+                        if pn.type == 'global' and pn.cate == 'type' and classGenericMap[pn.name] then
+                            -- Replace the global type reference with the resolved type
+                            newNode:merge(classGenericMap[pn.name])
+                        else
+                            newNode:merge(pn)
+                        end
+                    end
+                    defNode:merge(newNode)
+                else
+                    defNode:merge(paramNode)
+                end
                 if param[1] == '...' then
                     defNode:addOptional()
                 end
@@ -51,7 +103,7 @@ local function getDefNode(funcNode, i)
         return nil
     end
 
-    expandGenerics(defNode)
+    expandGenerics(defNode, classGenericMap)
 
     return defNode
 end
@@ -87,12 +139,14 @@ return function (uri, callback)
         end
         await.delay()
         local funcNode = vm.compileNode(source.node)
+        -- Get the class generic map for method calls on generic class instances
+        local classGenericMap = getReceiverGenericMap(uri, source)
         for i, arg in ipairs(source.args) do
             local refNode = vm.compileNode(arg)
             if not refNode then
                 goto CONTINUE
             end
-            local defNode = getDefNode(funcNode, i)
+            local defNode = getDefNode(funcNode, i, classGenericMap)
             if not defNode then
                 goto CONTINUE
             end

script/core/diagnostics/undefined-doc-name.lua

@@ -3,6 +3,100 @@ local guide   = require 'parser.guide'
 local lang    = require 'language'
 local vm      = require 'vm'
 
+--- Check if name is a generic parameter from a class context
+---@param source parser.object  The doc.type.name source
+---@param name string  The type name to check
+---@param uri uri  The file URI
+---@return boolean
+local function isClassGenericParam(source, name, uri)
+    -- Find containing doc node
+    local doc = guide.getParentTypes(source, {
+        ['doc.return'] = true,
+        ['doc.param'] = true,
+        ['doc.type'] = true,
+        ['doc.field'] = true,
+        ['doc.overload'] = true,
+        ['doc.vararg'] = true,
+    })
+    if not doc then
+        return false
+    end
+
+    -- Walk up to find a doc node with bindGroup (intermediate doc.type nodes don't have it)
+    while doc and not doc.bindGroup do
+        doc = doc.parent
+    end
+    if not doc then
+        return false
+    end
+
+    -- Check bindGroup for class/alias with matching generic sign
+    local bindGroup = doc.bindGroup
+    if bindGroup then
+        for _, other in ipairs(bindGroup) do
+            if (other.type == 'doc.class' or other.type == 'doc.alias') and other.signs then
+                for _, sign in ipairs(other.signs) do
+                    if sign[1] == name then
+                        return true
+                    end
+                end
+            end
+        end
+    end
+
+    -- Check direct class reference (for doc.field, doc.overload, doc.operator)
+    if doc.class and doc.class.signs then
+        for _, sign in ipairs(doc.class.signs) do
+            if sign[1] == name then
+                return true
+            end
+        end
+    end
+
+    -- Check if bound to a method on a generic class
+    -- Find the function from any doc in the bindGroup
+    local func = nil
+    if bindGroup then
+        for _, other in ipairs(bindGroup) do
+            local bindSource = other.bindSource
+            if bindSource then
+                if bindSource.type == 'function' then
+                    -- doc.return binds directly to function
+                    func = bindSource
+                    break
+                else
+                    -- doc.param binds to local param, find containing function
+                    func = guide.getParentFunction(bindSource)
+                    if func then
+                        break
+                    end
+                end
+            end
+        end
+    end
+
+    -- If we found a function, check if it's a method on a generic class
+    if func and func.parent then
+        local parent = func.parent
+        if parent.type == 'setmethod' or parent.type == 'setfield' or parent.type == 'setindex' then
+            local classGlobal = vm.getDefinedClass(uri, parent.node)
+            if classGlobal then
+                for _, set in ipairs(classGlobal:getSets(uri)) do
+                    if set.type == 'doc.class' and set.signs then
+                        for _, sign in ipairs(set.signs) do
+                            if sign[1] == name then
+                                return true
+                            end
+                        end
+                    end
+                end
+            end
+        end
+    end
+
+    return false
+end
+
 return function (uri, callback)
     local state = files.getState(uri)
     if not state then
@@ -25,6 +119,9 @@ return function (uri, callback)
         if name == '...' or name == '_' or name == 'self' then
             return
         end
+        if isClassGenericParam(source, name, uri) then
+            return
+        end
         if #vm.getDocSets(uri, name) > 0 then
             return
         end

script/parser/guide.lua

@@ -177,7 +177,7 @@ local childMap = {
     ['doc.generic.object'] = {'generic', 'extends', 'comment'},
     ['doc.vararg']         = {'vararg', 'comment'},
     ['doc.type.array']     = {'node'},
-    ['doc.type.function']  = {'#args', '#returns', 'comment'},
+    ['doc.type.function']  = {'#args', '#returns', '#signs', 'comment'},
     ['doc.type.table']     = {'#fields', 'comment'},
     ['doc.type.literal']   = {'node'},
     ['doc.type.arg']       = {'name', 'extends'},

script/parser/luadoc.lua

@@ -523,6 +523,8 @@ local function  parseTypeUnitFunction(parent)
         args    = {},
         returns = {},
     }
+    -- Parse optional generic params: fun<T, V>(...)
+    typeUnit.signs = parseSigns(typeUnit)
     if not nextSymbolOrError('(') then
         return nil
     end
@@ -617,6 +619,51 @@ local function  parseTypeUnitFunction(parent)
         end
     end
     typeUnit.finish = getFinish()
+    -- Bind local generics from fun<T, V> to type names within this function
+    if typeUnit.signs then
+        local generics = {}
+        for _, sign in ipairs(typeUnit.signs) do
+            generics[sign[1]] = sign
+        end
+        local function bindTypeNames(obj)
+            if not obj then return end
+            if obj.type == 'doc.type.name' and generics[obj[1]] then
+                obj.type = 'doc.generic.name'
+                obj.generic = generics[obj[1]]
+            elseif obj.type == 'doc.type' and obj.types then
+                for _, t in ipairs(obj.types) do
+                    bindTypeNames(t)
+                end
+            elseif obj.type == 'doc.type.array' then
+                bindTypeNames(obj.node)
+            elseif obj.type == 'doc.type.table' and obj.fields then
+                for _, field in ipairs(obj.fields) do
+                    bindTypeNames(field.name)
+                    bindTypeNames(field.extends)
+                end
+            elseif obj.type == 'doc.type.sign' then
+                bindTypeNames(obj.node)
+                if obj.signs then
+                    for _, s in ipairs(obj.signs) do
+                        bindTypeNames(s)
+                    end
+                end
+            elseif obj.type == 'doc.type.function' then
+                for _, arg in ipairs(obj.args) do
+                    bindTypeNames(arg.extends)
+                end
+                for _, ret in ipairs(obj.returns) do
+                    bindTypeNames(ret)
+                end
+            end
+        end
+        for _, arg in ipairs(typeUnit.args) do
+            bindTypeNames(arg.extends)
+        end
+        for _, ret in ipairs(typeUnit.returns) do
+            bindTypeNames(ret)
+        end
+    end
     return typeUnit
 end
 
@@ -1030,6 +1077,12 @@ local docSwitch = util.switch()
                 }
                 return result
             end
+            if extend.type == 'doc.extends.name' then
+                local signResult = parseTypeUnitSign(result, extend)
+                if signResult then
+                    extend = signResult
+                end
+            end
             result.extends[#result.extends+1] = extend
             result.finish = getFinish()
             if not checkToken('symbol', ',', 1) then
@@ -1850,7 +1903,9 @@ local function bindGeneric(binded)
         or doc.type == 'doc.return'
         or doc.type == 'doc.type'
         or doc.type == 'doc.class'
-        or doc.type == 'doc.alias' then
+        or doc.type == 'doc.alias'
+        or doc.type == 'doc.field'
+        or doc.type == 'doc.overload' then
             guide.eachSourceType(doc, 'doc.type.name', function (src)
                 local name = src[1]
                 if generics[name] then