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Fix dialyzer opaqueness violation with MapSet #15399

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Merged
sabiwara merged 1 commit into from
May 17, 2026
+7 −1
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Fix dialyzer opaqueness violation with MapSet #15399

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3 changes: 2 additions & 1 deletion lib/elixir/lib/map_set.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,8 @@ defmodule MapSet do

# We don't use @opaque (or `:sets.set` which is opaque) because MapSets can be inlined,
# either via module attributes or by the compiler.
@typep internal(value) :: %{optional(value) => term()}
# Defaulting to a broad `term()` type to prevent opaqueness violations.
@typep internal(_value) :: term()

@type t(value) :: %__MODULE__{map: internal(value)}
@type t :: t(term)
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5 changes: 5 additions & 0 deletions lib/elixir/test/elixir/fixtures/dialyzer/opaqueness.ex
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Expand Up @@ -14,6 +14,11 @@ defmodule Dialyzer.Opaqueness do
bar(@my_set)
end

def contains?(ids, id) do
id_set = MapSet.new(ids)
MapSet.member?(id_set, id)
end

# Task.Supervisor returns a Task.t() containing an opaque Task.ref()
@spec run_task() :: Task.t()
def run_task do
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