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Fix compiler crash on invalid nested bitstring #15280

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Merged
josevalim merged 3 commits into from
Apr 16, 2026
Merged

Fix compiler crash on invalid nested bitstring #15280

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22c20a6
Fix compiler crash on invalid nested bitstring
lukaszsamson Apr 16, 2026
b7dbdb4
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josevalim Apr 16, 2026
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josevalim Apr 16, 2026
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4 changes: 3 additions & 1 deletion lib/elixir/src/elixir_bitstring.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -115,7 +115,9 @@ concat_or_prepend_bitstring(Meta, {'<<>>', PartsMeta, Parts} = ELeft, ERight, Ac
[{'::', Meta, [ELeft, ERight]} | Acc]
end;
{bitstring, _, nil} ->
lists:reverse(Parts, Acc)
lists:reverse(Parts, Acc);
_ ->
[{'::', Meta, [ELeft, ERight]} | Acc]
end;
concat_or_prepend_bitstring(Meta, ELeft, ERight, Acc, _E, _RequireSize) ->
[{'::', Meta, [ELeft, ERight]} | Acc].
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6 changes: 6 additions & 0 deletions lib/elixir/test/elixir/kernel/binary_test.exs
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Expand Up @@ -196,6 +196,12 @@ defmodule Kernel.BinaryTest do
assert_compile_error(message, fn ->
Code.eval_string(~s[<<"foo"::float>>])
end)

assert_compile_error(message, fn ->
# We need to wrap the example below in a module because
# we attempt to continue compilation when inside a function
Code.compile_string("defmodule Repro do\n def run, do: <<(<<1>>)::integer>>\nend")
end)
end

@bitstring <<"foo", 16::4>>
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