1.99.19-beta breaks Flow build

[gabelevi]

For github.com/facebook/flow, 1.99.19-beta has broken our build

opam install ocp-build.1.99.18-beta
make all-ocp // Works fine
opam install ocp-build.1.99.19-beta
make all-ocp // Fails

The linker is failing with this error

Undefined symbols for architecture x86_64:
  "_LZ4_compressBound", referenced from:
      _write_at in libmlhh-heap.a(hh_shared.o)
  "_LZ4_compress_default", referenced from:
      _write_at in libmlhh-heap.a(hh_shared.o)
  "_LZ4_decompress_safe", referenced from:
      _hh_get_and_deserialize in libmlhh-heap.a(hh_shared.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
File "_none_", line 1:
Error: Error while building custom runtime system

The failing command for 1.99.19-beta looks like this

 '/Users/glevi/.opam/4.03.0/bin/ocamlc.opt' '-o' './_obuild/flow/flow.byte' '-I' './_obuild/flow' '-I' './src' '-I' './_obuild/flow-commands' '-I' '.' '-I' './_obuild/flow-server' '-I' './_obuild/hh-socket' '-I' './_obuild/flow-services-port' '-I' './_obuild/flow-services-inference' '-I' './_obuild/flow-server-env' '-I' './src/server' '-I' './_obuild/hh-dfind' '-I' './_obuild/tp-avl' '-I' './_obuild/hh-fsnotify' '-I' './_obuild/hh-fsnotify-darwin' '-I' './_obuild/flow-persistent-connection' '-I' './_obuild/flow-common-audit' '-I' './_obuild/flow-services-flowFileGen' '-I' './_obuild/flow-services-autocomplete' '-I' './_obuild/flow-typing' '-I' './_obuild/flow-parsing' '-I' './_obuild/flow-parser-utils' '-I' './_obuild/flow-common-errors' '-I' './_obuild/flow-common-profiling' '-I' './_obuild/flow-embedded' '-I' './_obuild/hh-win32res' '-I' './_obuild/hh-find' '-I' './_obuild/flow-shmem' '-I' './_obuild/flow-server-files' '-I' './_obuild/flow-common-config' '-I' './_obuild/flow-dts' '-I' './_obuild/flow-common' '-I' './_obuild/hh-procs' '-I' './_obuild/flow-stubs' '-I' './_obuild/flow-common-utils' '-I' './_obuild/hh-utils' '-I' './hack/utils' '-I' './_obuild/hh-utils-relative-path' '-I' './_obuild/hh-utils-sys' '-I' './_obuild/hh-utils-disk' '-I' './_obuild/hh-injector-default' '-I' './_obuild/hh-utils-string' '-I' './_obuild/hh-heap' '-I' './_obuild/lz4' '-I' './_obuild/hh-stubs' '-I' './_obuild/hh-utils-core' '-I' './_obuild/hh-utils-json' '-I' './_obuild/tp-core' '-I' './_obuild/hh-utils-collections' '-I' '/Users/glevi/.opam/4.03.0/lib/ocaml' '-I' './_obuild/flow-parser' '-I' '/Users/glevi/.opam/4.03.0/lib/sedlex' '-I' '/Users/glevi/.opam/4.03.0/lib/gen' '-I' './_obuild/ROOTPROJECT' '/Users/glevi/.opam/4.03.0/lib/ocaml/unix.cma' '/Users/glevi/.opam/4.03.0/lib/ocaml/bigarray.cma' '/Users/glevi/.opam/4.03.0/lib/gen/gen.cma' '/Users/glevi/.opam/4.03.0/lib/sedlex/sedlexing.cma' './_obuild/flow-parser/flow-parser.cma' '/Users/glevi/.opam/4.03.0/lib/ocaml/str.cma' '-thread' './_obuild/hh-utils-collections/hh-utils-collections.cma' '-thread' './_obuild/tp-core/tp-core.cma' '-thread' './_obuild/hh-utils-json/hh-utils-json.cma' '-thread' './_obuild/hh-utils-core/hh-utils-core.cma' '-thread' './_obuild/hh-stubs/hh-stubs.cma' '-thread' '-thread' './_obuild/hh-heap/hh-heap.cma' '-thread' './_obuild/hh-utils-string/hh-utils-string.cma' '-thread' './_obuild/hh-injector-default/hh-injector-default.cma' '-thread' './_obuild/hh-utils-disk/hh-utils-disk.cma' '-thread' './_obuild/hh-utils-sys/hh-utils-sys.cma' '-thread' './_obuild/hh-utils-relative-path/hh-utils-relative-path.cma' '-thread' './_obuild/hh-utils/hh-utils.cma' './_obuild/flow-common-utils/flow-common-utils.cma' './_obuild/flow-stubs/flow-stubs.cma' '-thread' './_obuild/hh-procs/hh-procs.cma' './_obuild/flow-common/flow-common.cma' './_obuild/flow-dts/flow-dts.cma' './_obuild/flow-common-config/flow-common-config.cma' './_obuild/flow-server-files/flow-server-files.cma' './_obuild/flow-shmem/flow-shmem.cma' '-thread' './_obuild/hh-find/hh-find.cma' '-thread' './_obuild/hh-win32res/hh-win32res.cma' './_obuild/flow-embedded/flow-embedded.cma' './_obuild/flow-common-profiling/flow-common-profiling.cma' './_obuild/flow-common-errors/flow-common-errors.cma' './_obuild/flow-parser-utils/flow-parser-utils.cma' './_obuild/flow-parsing/flow-parsing.cma' './_obuild/flow-typing/flow-typing.cma' './_obuild/flow-services-autocomplete/flow-services-autocomplete.cma' './_obuild/flow-services-flowFileGen/flow-services-flowFileGen.cma' './_obuild/flow-common-audit/flow-common-audit.cma' './_obuild/flow-persistent-connection/flow-persistent-connection.cma' '-thread' './_obuild/hh-fsnotify-darwin/hh-fsnotify-darwin.cma' '-thread' '-thread' './_obuild/tp-avl/tp-avl.cma' '-thread' './_obuild/hh-dfind/hh-dfind.cma' './_obuild/flow-server-env/flow-server-env.cma' './_obuild/flow-services-inference/flow-services-inference.cma' './_obuild/flow-services-port/flow-services-port.cma' '-thread' './_obuild/hh-socket/hh-socket.cma' './_obuild/flow-server/flow-server.cma' './_obuild/flow-commands/flow-commands.cma' './_obuild/flow/flow.cmo'

I think the key difference is that 1.99.19-beta is missing the '-cclib' '-lmllz4' which 1.99.18-beta has when I run it with --verbosity 4

The linking command that is failing looks like this for 1.99.18-beta

'/Users/glevi/.opam/4.03.0/bin/ocamlc.opt' '-o' './_obuild/flow/flow.byte' '-I' './_obuild/flow' '-I' './src' '-I' './_obuild/flow-commands' '-I' '.' '-I' './_obuild/flow-server' '-I' './_obuild/flow-services-inference' '-I' './_obuild/flow-server-env' '-I' './src/server' '-I' './_obuild/flow-persistent-connection' '-I' './_obuild/flow-services-autocomplete' '-I' './_obuild/flow-services-port' '-I' './_obuild/flow-services-flowFileGen' '-I' './_obuild/flow-embedded' '-I' './_obuild/flow-parsing' '-I' './_obuild/flow-shmem' '-I' './_obuild/flow-typing' '-I' './_obuild/flow-common-errors' '-I' './_obuild/flow-server-files' '-I' './_obuild/flow-common-config' '-I' './_obuild/hh-dfind' '-I' './_obuild/hh-fsnotify' '-I' './_obuild/flow-common' '-I' './_obuild/flow-common-profiling' '-I' './_obuild/flow-dts' '-I' './_obuild/flow-common-utils' '-I' './_obuild/hh-procs' '-I' './_obuild/hh-win32res' '-I' './_obuild/hh-find' '-I' './_obuild/hh-socket' '-I' './_obuild/hh-fsnotify-darwin' '-I' './_obuild/hh-utils' '-I' './hack/utils' '-I' './_obuild/hh-utils-relative-path' '-I' './_obuild/hh-heap' '-I' './_obuild/hh-utils-sys' '-I' './_obuild/hh-utils-core' '-I' './_obuild/hh-utils-json' '-I' './_obuild/hh-utils-disk' '-I' './_obuild/flow-parser-utils' '-I' './_obuild/flow-parser' '-I' './_obuild/lz4' '-I' './_obuild/hh-utils-string' '-I' './_obuild/hh-utils-collections' '-I' './_obuild/hh-injector-default' '-I' './_obuild/hh-stubs' '-I' './_obuild/tp-avl' '-I' './_obuild/tp-core' '-I' '/Users/glevi/.opam/4.03.0/lib/ocaml/threads' '-I' '/Users/glevi/.opam/4.03.0/lib/ocaml' '-I' '/Users/glevi/.opam/4.03.0/lib/sedlex' '-I' '/Users/glevi/.opam/4.03.0/lib/gen' '-I' './_obuild/ROOTPROJECT' '-I' './_obuild/flow-common-audit' '-I' './_obuild/flow-stubs' 'flow-stubs.cma' 'flow-common-audit.cma' 'str.cma' 'unix.cma' 'gen.cma' 'sedlexing.cma' 'bigarray.cma' '-thread' 'threads.cma' '-thread' 'tp-core.cma' '-thread' 'tp-avl.cma' '-thread' 'hh-stubs.cma' '-thread' 'hh-injector-default.cma' '-thread' 'hh-utils-collections.cma' '-thread' 'hh-utils-string.cma' '-thread' '-cclib' '-lmllz4' 'flow-parser.cma' 'flow-parser-utils.cma' '-thread' 'hh-utils-disk.cma' '-thread' 'hh-utils-json.cma' '-thread' 'hh-utils-core.cma' '-thread' 'hh-utils-sys.cma' '-thread' 'hh-heap.cma' '-thread' 'hh-utils-relative-path.cma' '-thread' 'hh-utils.cma' '-thread' 'hh-fsnotify-darwin.cma' '-thread' 'hh-socket.cma' '-thread' 'hh-find.cma' '-thread' 'hh-win32res.cma' '-thread' 'hh-procs.cma' 'flow-common-utils.cma' 'flow-dts.cma' 'flow-common-profiling.cma' 'flow-common.cma' '-thread' '-thread' 'hh-dfind.cma' 'flow-common-config.cma' 'flow-server-files.cma' 'flow-common-errors.cma' 'flow-typing.cma' 'flow-shmem.cma' 'flow-parsing.cma' 'flow-embedded.cma' 'flow-services-flowFileGen.cma' 'flow-services-port.cma' 'flow-services-autocomplete.cma' 'flow-persistent-connection.cma' 'flow-server-env.cma' 'flow-services-inference.cma' 'flow-server.cma' 'flow-commands.cma' './_obuild/flow/flow.cmo'

Our lz4 library is a c-only library, which is defined here: https://github.com/facebook/flow/blob/master/ocp_build_hack.ocp.fb#L23

The .ocp.fb files are basically just .ocp build but with file globbing support (when you run make all-ocp, it compiles the actual .ocp files)

[lefessan]

Fix is coming, I will hot-fix ocp-build 1.99.19-beta in OPAM:
#93

In the meantime, you can also add "autolink = true" in the lz4 description.