False positives on map literals with union/negation on variable keys

[lukaszsamson]

Existing issue

• I have searched existing issues and could not find a duplicate.

Elixir and Erlang/OTP versions

Erlang/OTP 28 [erts-16.4.0.1] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit]

Interactive Elixir (1.21.0-dev)

Operating system

any

Current behavior

Map literal expressions with variable keys produce too small types that do not contain observed runtime values and result in false positive warnings.

Issue 1: Map literal whose key is :a or integer() records :a as required

Repro:

    defmodule P22 do
      def fin_dom(c) do
        k = if c, do: :a, else: 5
        m = %{k => 1}
        case m do
          %{a: _} -> :has_a
          _ -> :no
        end
      end
    end

Result:

warning: the following clause cannot match because the previous clauses already matched all possible values:

    _ ->

it attempts to match on the result of:

    m

which has the already matched type:

    dynamic(%{integer() => integer(), a: integer()})

└─ iex:8: P22.fin_dom/1

Likely reason: closed_map/5 adds finite atoms as required keys even when domain_keys != []

Issue 2:

Map literals with a negated atom variable key mark the negated atom as not_set()

Repro:

    defmodule P21 do
      def neg_key(s1, s2) do
        k1 = String.to_atom(s1)
        k2 = case String.to_atom(s2) do :foo -> :not_foo; o -> o end
        m = %{k1 => :baz, k2 => :baz2}
        case m do
          %{foo: _} -> :has_foo
          _ -> :no
        end
      end

      def neg2(s1, s2) do
        k1 = case String.to_atom(s1) do :a -> :na; o -> o end
        k2 = case String.to_atom(s2) do :b -> :nb; o -> o end
        m = %{k1 => 1, k2 => 2}
        case m do
          %{b: _} -> :has_b
          _ -> :no
        end
      end
    end

Result:

warning: the following clause will never match:

    %{foo: _} ->

because it attempts to match on the result of:

    m

which has type:

    dynamic(%{atom() => :baz or :baz2, foo: not_set()})

└─ iex:9: P21.neg_key/2

warning: the following clause will never match:

    %{b: _} ->

because it attempts to match on the result of:

    m

which has type:

    dynamic(%{atom() => integer(), a: if_set(integer()), b: not_set()})

└─ iex:19: P21.neg2/2

IO.inspect({P21.neg_key("foo","bar"), P21.neg2("b","c")}) # {:has_foo, :has_b}

Note neg2 also shows the asymmetry: a is if_set (correct) but b is not_set (wrong)

Likely reason: closed_map/5 and union_negated/4 make every negated atom not_set() without consulting the :atom domain

Expected behavior

Proper types constructed, no warnings