'make erl' Compiling _build/default/lib/cowlib/src/cow_sse.erl failed

[philleer]

Hi, I am trying to test the compile flow, according to instructions from the doc: https://www.emqx.io/docs/zh/v5.0/extensions/plugins.html#_2-%E6%B5%8B%E8%AF%95%E7%BC%96%E8%AF%91%E7%8E%AF%E5%A2%83

Well, I just clone the repo and run make rel.
Unfortunately, I got the following error info

root@3210f365cfae:/home/emqx/emqx-plugin-template# make rel
/home/emqx/emqx-plugin-template/rebar3 emqx_plugrel tar
===> Verifying dependencies...
+ mkdir -p _build/cmake
+ cd _build/cmake
+ type cmake3
+ CMAKE=cmake
+ cmake -DWITH_BUNDLE_LZ4=ON -DWITH_BUNDLE_SNAPPY=ON ../../c_src
-- The C compiler identification is GNU 10.2.1
-- The CXX compiler identification is GNU 10.2.1
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- LZ4 library: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake/lz4/lib/liblz4.a
-- LZ4 includes: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake/lz4/include
-- Snappy library: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake/snappy/lib/libsnappy.a
-- Snappy includes: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake/snappy/include
-- cmake args -DCMAKE_POSITION_INDEPENDENT_CODE=ON;-DCMAKE_CXX_COMPILER=/usr/bin/c++;-DCMAKE_AR=/usr/bin/ar;-DCMAKE_BUILD_TYPE=Rel
ease;-DFAIL_ON_WARNINGS=OFF;-DPORTABLE=ON;-DUSE_RTTI=1;-DWITH_TOOLS=OFF;-DWITH_TESTS=OFF;-DWITH_GFLAGS=OFF;-DWITH_JEMALLOC=OFF;-DW
ITH_TBB=;-DWITH_SNAPPY=TRUE;-DWITH_LZ4=TRUE;-DWITH_ZLIB=;-DWITH_BZ2=;-DWITH_ZSTD=;-Dsnappy_ROOT_DIR=/home/emqx/emqx-plugin-templat
e/_build/default/lib/rocksdb/_build/cmake/snappy;-Dlz4_ROOT_DIR=/home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/
cmake/lz4
-- Found RocksDB library: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake/rocksdb-prefix/src/rocksdb-build
/librocksdb.a
-- Found RocksDB includes: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/c_src/../deps/rocksdb/include
-- Using OTP lib: /home/erlang/lib/erlang/lib - found
-- Using erl_interface version: erl_interface-5.4
-- Using erts version: erts-14.0
-- Performing Test HAVE_OMIT_LEAF_FRAME_POINTER
-- Performing Test HAVE_OMIT_LEAF_FRAME_POINTER - Success
-- Configuring done
-- Generating done
-- Build files have been written to: /home/emqx/emqx-plugin-template/_build/default/lib/rocksdb/_build/cmake
+ echo done-do_cmake.
done-do_cmake.
===> Compiling c_src/decoder.c
===> Compiling c_src/encoder.c
===> Compiling c_src/jiffy.c
===> Compiling c_src/termstack.c
===> Compiling c_src/utf8.c
===> Compiling c_src/util.c
===> Compiling c_src/doubles.cc
===> Compiling c_src/objects.cc
===> Compiling c_src/double-conversion/bignum-dtoa.cc
===> Compiling c_src/double-conversion/bignum.cc
===> Compiling c_src/double-conversion/cached-powers.cc
===> Compiling c_src/double-conversion/diy-fp.cc
===> Compiling c_src/double-conversion/double-conversion.cc
===> Compiling c_src/double-conversion/fast-dtoa.cc
===> Compiling c_src/double-conversion/fixed-dtoa.cc
===> Compiling c_src/double-conversion/strtod.cc
===> Linking /home/emqx/emqx-plugin-template/_build/default/lib/jiffy/priv/jiffy.so
===> Compiling c_src/async_queue.c
===> Compiling c_src/bcrypt.c
===> Compiling c_src/bcrypt_nif.c
===> Compiling c_src/blowfish.c
===> Linking /home/emqx/emqx-plugin-template/_build/default/lib/bcrypt/priv/bcrypt_nif.so
===> Analyzing applications...
===> Compiling rocksdb
===> Compiling recon
===> Compiling sext
===> Compiling snabbkaffe
===> Compiling lc
===> Compiling cowlib
===> Compiling _build/default/lib/cowlib/src/cow_sse.erl failed
_build/default/lib/cowlib/src/cow_sse.erl:56:29: type variable 'State' is only used once (is unbound)

make: *** [Makefile:49: rel] Error 1

Have no idea what does this mean, and how to fix the error? Any suggestions will be appreciated!

[JimMoen]

Hi, sorry for late reply. you can try to use the latest EMQX release to build.

• Pull the newest branch master
• Bump emqx to v5.0.25, see this commit
• Run make clean, then make rel

[zmstone]

we believe this issues has been fixed in later version.