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Problem with methods of generic classes #3339
Description
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, Annotations
Expected Behaviour
- Define a generic base class Foo with a method function which returns the generic type
- Inherit from the base class and specify the generic type
- Use the method and expect the specified generic type on the output
---@class Foo<T>
---@field myValue T
local base = {}
---@return T
function base:get()
return self.myValue
end
---@type Foo<number>
local ex1 = base --Use class directly
---@class Example2 : Foo<string>
local ex2 = ex1 --Start with a version with generic type specified
---@class Example3 : Foo<boolean>
local ex3 = base --Start with a version without the generic type specified
local I = ex1.myValue --Correct: number
local a = ex1:get() --Correct: number
local II = ex2.myValue --Correct: string
local b = ex2:get() --Correct: string
local III = ex3.myValue --Correct: boolean
local c = ex3:get() --Correct: booleanActual Behaviour
Attempting to expand the parent class directly displays a warning, (Example 3) but using a variable with specified type does not (Example 2).
The method defined in the parent class fails to infer the generic type from the child classes
---@class Foo<T>
---@field myValue T
local base = {}
---@return T
function base:get()
return self.myValue
end
---@type Foo<number>
local ex1 = base
---@class Example2 : Foo<string>
local ex2 = ex1
---@class Example3 : Foo<boolean>
local ex3 = base --Cannot assign 'Foo' to 'Example3'
local I = ex1.myValue --Correct: number
local a = ex1:get() --Correct: number
local II = ex2.myValue --Correct: string
local b = ex2:get() --Incorrect: T
local III = ex3.myValue --Correct: boolean
local c = ex3:get() --Incorrect: TReproduction steps
- Define a generic base class with a method function which returns the generic type
- Inherit from the base class and specify the generic type
- Use the method and expect the specified generic type on the output
Additional Notes
No response
Activity