Support Elixir ~> 1.12

Replace pinned variables in binary pattern sizes (^var) with
:erlang.split_binary/2 to support both Elixir 1.12+ and 1.20+
without warnings.

Author: ericmj

lib/mint/http1.ex

@@ -762,7 +762,7 @@ defmodule Mint.HTTP1 do
         {:ok, conn, responses}
 
       length <= byte_size(data) ->
-        <<body::binary-size(^length), rest::binary>> = data
+        {body, rest} = :erlang.split_binary(data, length)
         {conn, responses} = add_body(conn, body, responses)
         conn = request_done(conn)
         responses = [{:done, request_ref} | responses]
@@ -836,7 +836,7 @@ defmodule Mint.HTTP1 do
         {:ok, conn, responses}
 
       length <= byte_size(data) ->
-        <<body::binary-size(^length), rest::binary>> = data
+        {body, rest} = :erlang.split_binary(data, length)
         {conn, responses} = add_body(conn, body, responses)
         conn = put_in(conn.request.body, {:chunked, :crlf})
         decode_body({:chunked, :crlf}, conn, rest, request_ref, responses)

lib/mint/http2.ex

@@ -1266,7 +1266,7 @@ defmodule Mint.HTTP2 do
   end
 
   defp split_payload_in_chunks(binary, chunk_size, acc) do
-    <<chunk::size(^chunk_size)-binary, rest::binary>> = binary
+    {chunk, rest} = :erlang.split_binary(binary, chunk_size)
     split_payload_in_chunks(rest, chunk_size, [chunk | acc])
   end
 

lib/mint/http2/frame.ex

@@ -271,7 +271,7 @@ defmodule Mint.HTTP2.Frame do
     else
       # 1 byte is for the space taken by pad_length
       data_length = byte_size(payload) - pad_length - 1
-      <<data::size(^data_length)-binary, padding::size(^pad_length)-binary>> = rest
+      {data, padding} = :erlang.split_binary(rest, data_length)
       {data, padding}
     end
   end

mix.exs

@@ -8,7 +8,7 @@ defmodule Mint.MixProject do
     [
       app: :mint,
       version: @version,
-      elixir: "~> 1.15",
+      elixir: "~> 1.12",
       start_permanent: Mix.env() == :prod,
       elixirc_paths: elixirc_paths(Mix.env()),
       deps: deps(),

test/mint/http1/conn_properties_test.exs

@@ -90,7 +90,7 @@ defmodule Mint.HTTP1.PropertiesTest do
       |> Enum.sort()
       |> Enum.reduce({[], binary, 0}, fn split, {chunks, rest, prev_split} ->
         length = split - prev_split
-        <<chunk::binary-size(^length), rest::binary>> = rest
+        {chunk, rest} = :erlang.split_binary(rest, length)
         {[chunk | chunks], rest, split}
       end)
       |> join_last_chunk()