Hello everyone,
I’m encountering a truly baffling and persistent issue with Elixir’s bitstring syntax for little-endian integer encoding, and I’m hoping someone here might have seen something similar or can
shed some light on it.
The Problem: When attempting to convert a specific 32-bit unsigned integer (1749397227) to its little-endian binary representation, both the direct bitstring syntax
(<integer::unsigned-little-integer-size(32)>) and Erlang’s :binary.encode_unsigned(:little) function produce an incorrect byte order on my system.
• The integer 1749397227 in hexadecimal is 0x6874462B.
• Its correct Little-Endian binary representation should be <<0x2B, 0x46, 0x74, 0x68>>, which is “2B467468” in hex.
However, my system consistently produces <<0xEB, 0xAE, 0x45, 0x68>>, which is “EBAE4568” in hex.
Minimal iex Reproduction:
Please run these lines in your iex session and share the output:
my_int = 1749397227
le_bin = <<my_int::unsigned-little-integer-size(32)>>
expected_hex = "2B467468"
actual_hex = Base.encode16(le_bin)
IO.puts("--- Bitstring Test ---")
IO.puts("Integer: #{my_int}")
IO.puts("Expected LE: #{expected_hex}")
IO.puts("Actual LE: #{actual_hex}")
IO.puts("Match: #{actual_hex == expected_hex}")
# Also test Erlang's :binary module
erlang_le_bin = :binary.encode_unsigned(my_int, :little)
erlang_actual_hex = Base.encode16(erlang_le_bin)
IO.puts("\n--- Erlang :binary Test ---")
IO.puts("Expected LE: #{expected_hex}")
IO.puts("Actual LE: #{erlang_actual_hex}")
IO.puts("Match: #{erlang_actual_hex == expected_hex}")
My Observed Output (consistently):
— Bitstring Test —
Integer: 1749397227
Expected LE: 2B467468
Actual LE: EBAE4568
Match: false
— Erlang :binary Test —
Expected LE: 2B467468
Actual LE: EBAE4568
Match: false
Troubleshooting Steps Taken (Extensive):
1 Confirmed source code (lib/util/crypto.ex) uses the correct bitstring syntax.
2 Confirmed manual bitwise operations (<<val &&& 0xFF, …>>) do produce the correct “2B467468” when run directly in iex.
3 Performed multiple mix clean --all and rm -rf _build deps priv/repo/migrations.
4 Performed a complete reinstallation of Elixir and Erlang/OTP using asdf (uninstalling, clearing ~/.asdf/downloads and build caches, then reinstalling stable Erlang 27.0 and Elixir
1.18.3-otp-27).
5 Confirmed elixir --version shows the newly installed versions.
6 Ran mix test and direct function calls in iex -S mix after each step.
Despite all this, the issue persists. This suggests a very deep environmental problem.
My System Information:
• elixir --version output: (Paste your actual output here, e.g., Erlang/OTP 27 [erts-15.2.3] … Elixir 1.18.3 (compiled with Erlang/OTP 27))
• Operating System: (e.g., Ubuntu 22.04 LTS)
• CPU Architecture: (e.g., x86_64, ARM64)
Has anyone ever encountered such a fundamental and persistent issue with bitstring encoding in Elixir/Erlang? Any insights or further diagnostic steps would be greatly appreciated!
Thank you!
