Issue with "where" in a nested record

[mtdowling]

The generated code for a where clause doesn't include the required outer variable, causing it to evaluate to nil:

local record mod
    record Foo where self.kind == Foo
        kind: self
    end
end

local instance: mod.Foo = {kind = mod.Foo}

-- Does not work:
if instance is mod.Foo then
    print("[1] It is a Foo!")
end

-- Works:
local Foo = mod.Foo
if instance is Foo then
    print("[2] It is a Foo!")
end

Generated Lua code:

local mod = { Foo = {} }





local instance = { kind = mod.Foo }


if instance.kind == Foo then
   print("[1] It is a Foo!")
end


local Foo = mod.Foo
if instance.kind == Foo then
   print("[2] It is a Foo!")
end

[catwell]

Note that this also works:

local record mod
    record Foo where self.kind == mod.Foo
        kind: self
    end
end

local instance: mod.Foo = {kind = mod.Foo}

if instance is mod.Foo then
    print("It is a Foo!")
end

However this obviously won't:

--- foo.tl

local record mod
    record Foo where self.kind == mod.Foo
        kind: self
    end
end

return mod

--- bar.tl

local foo = require "foo"

local instance: foo.Foo = {kind = foo.Foo}

if instance is foo.Foo then
    print("It is a Foo!")
end

Running bar.tl will cause attempt to index a nil value (global 'mod').

This is not related to the nesting, this is the behavior of where clauses, e.g. this fails too (it generates a reference to sentinel which is not defined):

--- foo.tl

local sentinel = table.concat

local record Foo where self.kind == sentinel
    kind: function
end

return Foo

--- bar.tl

local Foo = require "foo"

local instance: Foo = {kind = table.concat}

if instance is Foo then
    print("It is a Foo!")
end

I have never tried using where clauses this way (with variables outside of self), I am not sure if it should be allowed. Currently they just behave like "macros" i.e. they are copied as is.

[hishamhm]

Yeah, where clauses are non-hygienic macros. I think we do need to support variables outside self (since functions are variables too). For now, this is just a quirk we'll have to live with for simplicity's sake.