Skip to content

Class inheriting a generic class with specified type not recognized as inherited class (assign-type-mismatch) #3345

@FireRune

Description

@FireRune

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Type Checking

Expected Behaviour

The type of a class inheriting a generic class (when specifying the type) should be recognized as the same type as the class it inherits.
If that generic class inherits another class, that should also be recognized.
As such, the following code should have no problems.

--- @class Test_Base
--- @field Str_A string
local Test_Base = {}

--- @generic T
--- @class Test_Generic<T> : Test_Base
--- @field Gen_T T
local Test_Generic = {}

--- @class Test_Class : Test_Generic<string>
local Test_Class = {}

--- @type Test_Base[]
local testArray = {
    Test_Base,
    Test_Generic,
    Test_Class,
}

Actual Behaviour

"Test_Class" isn't recognized as either "Test_Generic" or "Test_Base", therefore showing as an "assign-type-mismatch" error.

Image

However, inheriting the generic class without specifying the type is completely fine.

--- @class Test_Base
--- @field Str_A string
local Test_Base = {}

--- @generic T
--- @class Test_Generic<T> : Test_Base
--- @field Gen_T T
local Test_Generic = {}

--- @class Test_Class : Test_Generic
local Test_Class = {}

--- @type Test_Base[]
local testArray = {
    Test_Base,
    Test_Generic,
    Test_Class,
}

Reproduction steps

--- @class Test_Base
--- @field Str_A string
local Test_Base = {}

--- @generic T
--- @class Test_Generic<T> : Test_Base
--- @field Gen_T T
local Test_Generic = {}

--- @class Test_Class1 : Test_Generic<string>
local Test_Class1 = {}

--- @class Test_Class2 : Test_Generic
local Test_Class2 = {}

--- @type Test_Base[]
local testArray = {
    Test_Base,
    Test_Generic,
    Test_Class1,
    Test_Class2,
}

Additional Notes

This problem showed up after the release of version 3.17.0

I know that the implementation of generics is complicated, and I've already found a workaround for my use-case by casting the inheriting classes to the type of the underlying base class. But that may not work for others.

Log File

No response

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions