Closed
Description
Type guards with unions that include a record (table) will only check for the table. Other values included in the union will not be captured.
global record Foo
bar : string
end
global function repro(x:Foo|string|nil) : integer
local y = x
if y is string | Foo then
return 1
elseif y is nil then
return 2
end
return 3 -- string falls through here!
end
print(repro({} as Foo)) --1
print(repro("1")) --3
print(repro(nil)) --2
Workaround
You can add a manual type guard in place of the union, which then gets inferred, but only if:
- it's in an
elseifblock and - the
ifstatement starts with anisexpression
global function repro(x:Foo|string|nil) : integer
local y = x
if y is nil then
local z : nil = y
return 2
elseif type(y) == "table" or type(y) == "string" then
local z : Foo | string = y
return 1
end
return 3 --No fall through
end