Map update propagates replacement type refinement to the original map

[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 update incorrectly refines original map fields with replacement type constraints

Repro 1:

    defmodule MapOverwrite do
      def replace(m), do: %{m | a: 1}.a + 1
      def run, do: replace(%{a: :old})

      def original(m) do
        %{a: 1} = %{m | a: 1}

        case m.a do
          :old -> :kept_original
          _ -> :other
        end
      end
    end

    IO.inspect(MapOverwrite.run())
    IO.inspect(MapOverwrite.original(%{a: :old}))

Result: code works fine and prints:

2
:kept_original

but raises 2 false positive warnings:

warning: incompatible types given to replace/1:

    replace(%{a: :old})

given types:

    %{a: :old}

but expected one of:

    %{..., a: float() or integer()}

└─ iex:3: MapOverwrite.run/0

warning: the following clause will never match:

    :old ->

because it attempts to match on the result of:

    m.a

which has type:

    integer()

└─ iex:9: MapOverwrite.original/1

Another repro:

   defmodule MapOverwriteCase do
      def original(m) do
        case %{m | a: 1} do
          %{a: 1} -> :ok
        end

        case m.a do
          :old -> :kept_original
          _ -> :other
        end
      end

      def domain(m) do
        case %{m | a: 1} do
          %{a: 1} -> :ok
        end
      end

      def run, do: domain(%{a: :old})
    end

    IO.inspect(MapOverwriteCase.original(%{a: :old}))
    IO.inspect(MapOverwriteCase.run())

Result:

:kept_original
:ok

False positive warnings:

warning: the following clause will never match:

    :old ->

because it attempts to match on the result of:

    m.a

which has type:

    integer()

└─ iex:11: MapOverwriteCase.original/1

warning: incompatible types given to domain/1:

    domain(%{a: :old})

given types:

    %{a: :old}

but expected one of:

    %{..., a: integer()}

└─ iex:22: MapOverwriteCase.run/0

Note list and tuple does not seem to be affected by similar bugs.
This is a distinct bug from #15509 and #15688

Expected behavior

The type system should require the key to exist in the original map but without constraining its value type to the replacement