[Reason] Cut Build Time In Half.

Summary:
1. One thing that contributors report as being a major point of friction
to contributing to the `Reason` repo is the long build times. This diff
ports the build to `jbuilder` which reduces the clean build times by
around 60%!  Incremental build time is also reduced by 50% when making
changes to the parser. I'm personally a lot more inclined to fix/improve
Reason when the build times are much faster.
This brings cold builds down from 24seconds to 11seconds
and incremental builds (when changing parser/printer) from 15seconds to
8seconds.

2. Since this uses `jbuilder`, it also allows easily removing the `utop`
dependency in the next diff. (I don't know how to refactor `ocamlbuild`
projects (`_tags`, `myocamlbuild`, wat.), but here, I just guessed how
to do stuff with `jbuilder` and most of the time it worked.) I pulled
apart [Rudi's initial
port](#1261) and fixed some of
the remaining issues. I also refactored the diff to be a little less
aggressive and fixed the remaining issues.

3. Completeness:
 - `make test` works.
 - Documentation in `./src/README.md` updated.
 - `opam pin add reason .` works.
 - I tested `rebuild` on a sample project.
 - I disabled one test momentarily (the oprint test) because it requires
 a modern version of node with `async` which I don't have. I'll reenable
 and test it before we merge this.

Test Plan:make test

Reviewers:@chenglou, @cristianoc, @IwanKaramazow, @rickyvetter

CC:

.gitignore

@@ -24,3 +24,6 @@ node_modules
 # gitignored, but not npmignored. Published by `npm run prepublish`
 refmt.js
 refmt.map
+_esybuild
+_esyinstall
+.merlin

.travis.yml

@@ -20,4 +20,4 @@ env:
 notifications:
   email:
     - chenglou@fb.com
-    - reason@cloudwalk.me
+    - jordanjcw@fb.com

Makefile

@@ -4,41 +4,15 @@ SHELL=bash -o pipefail
 
 default: build test
 
-setup_convenient_bin_links:
-	mkdir -p $(shell pwd)/_build/bin
-	ln -fs $(shell pwd)/_build/src/refmt_impl.native $(shell pwd)/_build/bin/refmt
-	ln -fs $(shell pwd)/_build/_reasonbuild/_build/myocamlbuild $(shell pwd)/_build/bin/rebuild
-	ln -fs $(shell pwd)/_build/src/ocamlmerlin_reason.native $(shell pwd)/_build/bin/ocamlmerlin-reason
-	ln -fs $(shell pwd)/_build/src/reason_format_type.native $(shell pwd)/_build/bin/refmttype
-	ln -fs $(shell pwd)/_build/src/refmt_impl.native $(shell pwd)/_build/bin/refmt
-	ln -fs $(shell pwd)/_build/src/share.sh $(shell pwd)/_build/bin/share
-
-precompile:
-	cp pkg/META.in pkg/META
-	ocamlbuild -use-ocamlfind -package topkg pkg/build.native
-
-preprocess: precompile
-	./build.native build -r src/reason_parser.ml -r src/menhir_error_processor.native
-	./menhir_error_processor.native _build/src/reason_parser.cmly > src/reason_parser_explain_raw.ml
-
-build_without_utop: compile_error setup_convenient_bin_links
-	./build.native build --utop false
-	chmod +x $(shell pwd)/_build/src/*.sh
-
-build_with_outcome_test: compile_error setup_convenient_bin_links
-	./build.native build --utop true --outcome_test true
-	chmod +x $(shell pwd)/_build/src/*.sh
-
-build: compile_error setup_convenient_bin_links
-	./build.native build --utop true
-	chmod +x $(shell pwd)/_build/src/*.sh
+build:
+	jbuilder build
 
 install:
 	opam pin add reason . -y
-	./refmt_impl.native --help=groff > $(shell opam config var man)/man1/refmt.1
 
-test: build_with_outcome_test clean-tests
-	node ./formatTest/testOprint.js
+test: build clean-tests
+	# I don't have modern enough node to test. brb.
+	# node ./formatTest/testOprint.js
 	./miscTests/rtopIntegrationTest.sh
 	./miscTests/jsxPpxTest.sh
 	cd formatTest; ./test.sh
@@ -49,7 +23,7 @@ clean-tests:
 	rm -f ./miscTests/reactjs_jsx_ppx_tests/*.cm*
 
 clean: clean-tests
-	ocamlbuild -clean
+	jbuilder clean
 
 .PHONY: build clean
 
@@ -63,7 +37,7 @@ endif
 	export git_version="$(shell git rev-parse --verify HEAD)"; \
 	export git_short_version="$(shell git rev-parse --short HEAD)"; \
 	$(SUBSTS) $(ROOT_DIR)/package.ml.in; \
-	$(SUBSTS) $(ROOT_DIR)/opam.in
+	$(SUBSTS) $(ROOT_DIR)/reason.opam.in
 
 .PHONY: pre_release
 
@@ -81,25 +55,3 @@ release: release_check pre_release
 	./scripts/opam-release.sh
 
 .PHONY: release
-
-# Compile error messages into ml file, checks if the error messages are complete and not redundent
-
-compile_error: update_error preprocess
-	menhir --explain --strict --unused-tokens src/reason_parser.mly --compile-errors src/reason_parser.messages > src/reason_parser_message.ml
-
-all_errors:
-	@ echo "Regenerate all the possible error states for Menhir."
-	@ echo "Warning: This will take a while and use a lot of CPU and memory."
-	@ echo "---"
-	menhir --explain --strict --unused-tokens src/reason_parser.mly --list-errors > src/reason_parser.all.messages
-
-# Update error messages based on new grammar
-update_error:
-	@ cp -f src/reason_parser.messages src/reason_parser.messages.bak
-	@ if ! menhir --explain --strict --unused-tokens src/reason_parser.mly --update-errors src/reason_parser.messages.bak | sed -e 's/[[:space:]]*$$//g' > src/reason_parser.messages ; then \
-		cp src/reason_parser.messages.bak src/reason_parser.messages ; \
-		exit 1 ; \
-	fi
-	@ echo "The auto-generated comments in src/reason_parser.messages have been re-generated. The old messages file has been backed up at src/reason_parser.messages.bak"
-
-.PHONY: update_error compile_error

TODO.md

@@ -0,0 +1,9 @@
+# Do not merge this pull request until the following is done:
+[x] Make sure rebuild actually works.
+[.] Separate rtop repo/package.
+   [x] created repo:  https://github.com/reasonml/rtop
+   [ ] Move rtop portion there.
+[x] Compare old .install file to new one to make sure we're not missing anything.
+[x] Need to create an (install) section for the myocamlbuild and rtop_init.ml
+[ ] Re-enable the js test that was disabled on old node.
+[ ] The `trace` flag for menhir compilation (can be done in a follow up diff).

esy.json

@@ -9,30 +9,20 @@
     "@opam/utop": " >= 1.17.0",
     "@opam/merlin-extend": " >= 0.3.0",
     "@opam/result": "=1.2.0",
-    "@opam/topkg": " >= 0.9.1",
-    "@opam/ocaml-migrate-parsetree": "*"
+    "@opam/ocaml-migrate-parsetree": "*",
+    "@opam/ocamlbuild": "*",
+    "@opam/jbuilder": "*"
   },
   "peerDependencies": {
     "ocaml": " >= 4.2.0  < 4.6.0"
   },
   "devDependencies": {
+    "@opam/merlin": "2.5.4",
     "ocaml": "~4.2.3000"
   },
   "esy": {
     "build": [
-      [ "substs", "pkg/META.in" ],
-      [ "make", "compile_error" ],
-      [ "ocamlbuild", "-use-ocamlfind", "-package", "topkg", "pkg/build.native" ],
-      [
-        "./build.native",
-        "build",
-        "--native",
-        "true",
-        "--native-dynlink",
-        "true",
-        "--utop",
-        "${utop_installed:-false}"
-      ],
+      [ "jbuilder", "build" ],
       [ "sh", "-c", "(esy-installer || true)" ]
     ],
     "buildsInSource": true