Record embed and const field syntax

spec/declaration/record_spec.lua

@@ -673,3 +673,158 @@ for i, name in ipairs({"records", "arrayrecords"}) do
       ]]))
    end)
 end
+
+describe("embedding", function()
+   it("embed is not a reserved word", util.check [[
+      local record A
+         embed: number
+      end
+   ]])
+   it("should make members of a record available to another", util.check [[
+      local record A
+         userdata
+         a_value: number
+      end
+      local record B
+         embed A
+         b_value: number
+      end
+      local record C
+         embed B
+         c_value: string
+      end
+      local b: B = {}
+      local c: C = {}
+      print(b.a_value, c.a_value + c.b_value, c.c_value)
+      local function f(a: A, b: B) end
+      f(b, b)
+      f(c, c)
+      local a: A = b
+      a = c
+   ]])
+   it("should allow for generics", util.check [[
+      local record A<T>
+         property_of_a: T
+      end
+      local record B<T>
+         embed A<T>
+         property_of_b: T
+      end
+      local record C<T>
+         embed B<T>
+         property_of_c: string
+      end
+      local b: B<number> = {}
+      local c: C<number> = {}
+      print(b.property_of_a + 1, c.property_of_b + c.property_of_a, c.property_of_c)
+      local function f(a: A<number>, b: B<number>) end
+      f(b, b)
+      f(c, c)
+      local a: A<number> = b
+      a = c
+   ]])
+   it("embed multiple records", util.check [[
+      local record A
+         x: number
+      end
+      local record B
+         y: string
+      end
+      local record C
+         embed A
+         embed B
+         z: boolean
+      end
+      local c: C = { x = 1, y = "hello", z = true }
+      print(c.x, c.y, c.z)
+      local function f(a: A, b: B, c: C) end
+      f(c, c, c)
+   ]])
+   it("share the same element type with embeded arrayrecord", util.check [[
+      local record A
+         { string }
+         x: number
+      end
+      local record B
+         embed A
+         y: string
+      end
+      local record C
+         embed B
+         z: boolean
+      end
+      local c: C = { x = 1, y = "hello", z = true }
+      local str: string = c[1]
+      print(c.x, c.y, c.z)
+      local strs: {string} = c
+      local b: B = c
+      strs = b
+   ]])
+   it("subrecords should not be equal", util.check_type_error([[
+      local record A
+      end
+      local record B
+         embed A
+      end
+      local record C
+         embed A
+      end
+      local a: A
+      local b: B
+      local c: C
+      a = b
+      a = c
+      b = c
+   ]], {
+      { y = 14, msg = "in assignment: C is not a B" }
+   }))
+end)
+
+describe("const field", function()
+   it("const is not a reserved word", util.check [[
+      local record A
+         const: boolean
+      end
+   ]])
+   it("cannot assign to a const field", util.check_type_error([[
+      local record A
+         const ["a field"]: string
+         const x: number
+      end
+      local record B
+         embed A
+         b: A
+      end
+      local r: B = {b = {["a field"] = "abc"}}
+      r.b[ [=[a field]=] ] = 456
+      r.x = 123
+   ]], {
+      { y = 10, msg = "cannot assign to const field \"a field\"" },
+      { y = 10, msg = "in assignment: got integer, expected string" },
+      { y = 11, msg = "cannot assign to const field \"x\"" }
+   }))
+   it("should work for generics", util.check_type_error([[
+      local record A<T>
+         const a: T
+      end
+      local record B<T>
+         embed A<T>
+         const b: T
+      end
+      local b: B<number> = { a = 1, b = 2 }
+      print(b.a, b.b)
+      b.a, b.b = 2, "3"
+   ]], {
+      { y = 10, msg = "cannot assign to const field \"a\"" },
+      { y = 10, msg = "cannot assign to const field \"b\"" },
+      { y = 10, msg = "in assignment: got string \"3\", expected number" }
+   }))
+   it("it is OK to modify const field with rawset", util.check [[
+      local record R
+         const x: boolean
+      end
+      local r: R = { x = true }
+      rawset(r, "x", false)
+   ]])
+end)
+