[build] avoid race condition, and do not run atdgen twice, add ocaml_clean

Summary:
Fixes 2 issues with the build:
- The OCaml dependencies (Version.ml, atdgen-generated stuff, ...) would be generated twice when running `make -j test` from a clean tree, because `make` has no inter-Makefile visibility over common dependencies.
- We would run `atdgen` twice: once for the .ml, once for the .mli, even though one invocation is enough for both.

Add `make ocaml_clean` to nuke only the OCaml code (in particular because
rebuilding the C++ code in the plugin is slow when all I want to get rid of the
OCaml stuff).

Reviewed By: mbouaziz

Differential Revision: D5415318

fbshipit-source-id: 16f42c6

Makefile

@@ -123,18 +123,24 @@ SRC_ML:=$(shell find * \( -name _build -or -name facebook-clang-plugins -or -pat
 fmt_all:
 	parallel $(OCAMLFORMAT_EXE) --no-warn-error -i ::: $(SRC_ML)
 
+# pre-building these avoids race conditions when building, eg src_build and test_build in parallel
+.PHONY: src_build_common
+src_build_common:
+	$(QUIET)$(call silent_on_success,Generating source dependencies,\
+	$(MAKE) -C $(SRC_DIR) src_build_common)
+
 .PHONY: src_build
-src_build:
+src_build: src_build_common
 	$(QUIET)$(call silent_on_success,Building native Infer,\
 	$(MAKE) -C $(SRC_DIR) infer)
 
 .PHONY: byte
-byte:
+byte: src_build_common
 	$(QUIET)$(call silent_on_success,Building byte Infer,\
 	$(MAKE) -C $(SRC_DIR) byte)
 
 .PHONY: test_build
-test_build:
+test_build: src_build_common
 	$(QUIET)$(call silent_on_success,Testing Infer builds without warnings,\
 	$(MAKE) -C $(SRC_DIR) TEST=1 byte_no_install)
 #	byte_no_install builds most of what toplevel needs, so it's more efficient to run the
@@ -148,7 +154,7 @@ byte src_build test_build: fb-setup
 endif
 
 ifeq ($(BUILD_C_ANALYZERS),yes)
-byte src_build test_build: clang_plugin
+byte src_build src_build_common test_build: clang_plugin
 endif
 
 $(INFER_COMMAND_MANUALS): src_build Makefile
@@ -313,7 +319,7 @@ check_missing_mli:
 	    test -f "$$x"i || echo Missing "$$x"i; done
 
 .PHONY: toplevel
-toplevel: clang_plugin
+toplevel: clang_plugin src_build_common
 	$(QUIET)$(MAKE) -C $(SRC_DIR) toplevel
 
 .PHONY: inferScriptMode_test
@@ -496,21 +502,29 @@ ifeq ($(IS_FACEBOOK_TREE),yes)
 	$(QUIET)$(MAKE) -C facebook install
 endif
 
-.PHONY: clean
-clean: test_clean
+# Nuke objects built from OCaml. Useful when changing the OCaml compiler, for instance.
+.PHONY: ocaml_clean
+ocaml_clean:
 ifeq ($(IS_RELEASE_TREE),no)
 ifeq ($(BUILD_C_ANALYZERS),yes)
-	$(QUIET)$(MAKE) -C $(FCP_DIR) clean
 	$(QUIET)$(MAKE) -C $(FCP_DIR)/clang-ocaml clean
 endif
 endif
 	$(QUIET)$(MAKE) -C $(SRC_DIR) clean
+	$(QUIET)$(MAKE) -C $(DEPENDENCIES_DIR)/ocamldot clean
+
+.PHONY: clean
+clean: test_clean ocaml_clean
+ifeq ($(IS_RELEASE_TREE),no)
+ifeq ($(BUILD_C_ANALYZERS),yes)
+	$(QUIET)$(MAKE) -C $(FCP_DIR) clean
+endif
+endif
 	$(QUIET)$(MAKE) -C $(ANNOTATIONS_DIR) clean
 	$(QUIET)$(MAKE) -C $(MODELS_DIR) clean
 ifeq ($(IS_FACEBOOK_TREE),yes)
 	$(QUIET)$(MAKE) -C facebook clean
 endif
-	$(QUIET)$(MAKE) -C $(DEPENDENCIES_DIR)/ocamldot clean
 	find $(INFER_DIR)/tests \( -name '*.o' -o -name '*.o.sh' \) -delete
 	$(QUIET)$(REMOVE_DIR) _build_logs $(MAN_DIR)
 

infer/src/Makefile

@@ -185,10 +185,16 @@ OCAML_ALL_SOURCES = $(OCAML_BASE_SOURCES) $(CLANG_ATDGEN_STUBS) $(CLANG_PLUGIN_M
 .PHONY: all
 all: infer
 
+.PHONY: src_build_common
+src_build_common: base/Version.ml $(OCAML_CONFIG_SOURCES)
+
+ifeq ($(BUILD_C_ANALYZERS),yes)
+src_build_common: $(CLANG_BINIOU_DICT)
+endif
+
 # single out infer.native as the source of truth for make, knowing that in fact several targets are
 # produced by the build
-$(INFER_BUILD_DIR)/$(INFER_MAIN).native: base/Version.ml $(OCAML_CONFIG_SOURCES) \
-                                         $(MAKEFILE_LIST)
+$(INFER_BUILD_DIR)/$(INFER_MAIN).native: src_build_common $(MAKEFILE_LIST)
 	$(MKDIR_P) $(BASE_BUILD_DIR)
 	$(OCAMLBUILD_CONFIG) -build-dir $(INFER_BUILD_DIR) \
 	  $(INFER_CONFIG_TARGETS)
@@ -215,12 +221,7 @@ endif
 .PHONY: infer
 infer: $(INFER_BIN).native
 
-ifeq ($(BUILD_C_ANALYZERS),yes)
-infer: $(CLANG_BINIOU_DICT)
-endif
-
-$(INFER_BUILD_DIR)/$(INFER_MAIN).byte: base/Version.ml $(OCAML_CONFIG_SOURCES) \
-                                       $(MAKEFILE_LIST)
+$(INFER_BUILD_DIR)/$(INFER_MAIN).byte: src_build_common $(MAKEFILE_LIST)
 	$(MKDIR_P) $(BASE_BUILD_DIR)
 	$(OCAMLBUILD_CONFIG) -build-dir $(INFER_BUILD_DIR) \
 	  $(INFER_CONFIG_TARGETS:.native=.byte)
@@ -251,7 +252,7 @@ M=
 MFLAGS=
 
 .PHONY: module
-module: base/Version.ml $(OCAML_ALL_SOURCES)
+module: src_build_common $(OCAML_ALL_SOURCES)
 	$(MKDIR_P) $(BASE_BUILD_DIR)
 	$(OCAMLBUILD_ALL) -build-dir $(INFER_BUILD_DIR) \
           $(MFLAGS) \
@@ -293,7 +294,7 @@ $(shell \
   | awk 'BEGIN { FS = "/"; OFS = "/" } ; {$$NF=toupper(substr($$NF,1,1))substr($$NF,2); print $$0}')
 endef
 
-toplevel.mlpack: base/Version.ml $(OCAML_CONFIG_SOURCES) $(MAKEFILE_LIST)
+toplevel.mlpack: src_build_common $(MAKEFILE_LIST)
 #	We need to pack all the infer modules into another module to avoid name clashes with some
 #	of them coming from ocaml libraries (Ident for example).  To do that, we generate a .mlpack
 #	file containing namespaced modules.
@@ -332,11 +333,11 @@ $(CHECKCOPYRIGHT_BIN): $(CHECKCOPYRIGHT_MAIN).ml $(MAKEFILE_LIST)
 define gen_atdgen_rules
 # generate files using atdgen
 # parameters:
-#   1. the .atd file to generate .ml{,i} files from
-#   2. the base name of .ml{,i} files
+#   1. the .atd file to generate .ml{,i} files from, e.g. foo.atd
+#   2. the base name of .ml{,i} files, e.g. foo
 #   3. the type of files to generate: b, j, t, or v
 
-$(2)_$(3).ml $(2)_$(3).mli: $(1)
+$(2)_$(3).mli: $(1)
 	$(ATDGEN) -$(3) $$< -o $(2)
 
 # the .ml depends on the corresponding .mli to avoid running atdgen