Add initial 'make rebar.config'

This is a preliminary work, good enough to be used in some,
but not all, projects. Tests cover the current functionality.
Documentation has been written but will be committed at a
later stage, as it covers more than just this target (the
target is documented as part of a "Compatibility with other
build tools" chapter).

build.config

@@ -16,6 +16,7 @@ plugins/protobuffs
 core/erlc
 core/docs
 core/test
+core/compat
 
 # Plugins.
 plugins/asciidoc

core/compat.mk

@@ -0,0 +1,25 @@
+# Copyright (c) 2015, Loïc Hoguin <essen@ninenines.eu>
+# This file is part of erlang.mk and subject to the terms of the ISC License.
+
+.PHONY: rebar.config
+
+# We strip out -Werror because we don't want to fail due to
+# warnings when used as a dependency.
+
+define compat_convert_erlc_opt
+$(if $(filter-out -Werror,$1),\
+	$(if $(findstring +,$1),\
+		$(shell echo $1 | cut -b 2-)))
+endef
+
+define compat_rebar_config
+{deps, [$(call comma_list,$(foreach d,$(DEPS),\
+	{$(call dep_name,$d),".*",{git,"$(call dep_repo,$d)","$(call dep_commit,$d)"}}))]}.
+{erl_opts, [$(call comma_list,$(foreach o,$(ERLC_OPTS),$(call compat_convert_erlc_opt,$o)))]}.
+endef
+
+$(eval _compat_rebar_config = $$(compat_rebar_config))
+$(eval export _compat_rebar_config)
+
+rebar.config:
+	$(gen_verbose) echo "$${_compat_rebar_config}" > rebar.config

test/core_compat.mk

@@ -0,0 +1,169 @@
+# Core: Compatibility with other build tools.
+#
+# Note: autopatch functionality is covered separately.
+
+CORE_COMPAT_CASES = auto-rebar rebar rebar-deps rebar-deps-pkg rebar-erlc-opts
+CORE_COMPAT_TARGETS = $(addprefix core-compat-,$(CORE_COMPAT_CASES))
+CORE_COMPAT_CLEAN_TARGETS = $(addprefix clean-,$(CORE_COMPAT_TARGETS))
+
+.PHONY: core-compat $(CORE_COMPAT_TARGETS) clean-core-compat $(CORE_COMPAT_CLEAN_TARGETS)
+
+clean-core-compat: $(CORE_COMPAT_CLEAN_TARGETS)
+
+$(CORE_COMPAT_CLEAN_TARGETS):
+	$t rm -rf $(APP_TO_CLEAN)/
+
+core-compat: $(CORE_COMPAT_TARGETS)
+
+core-compat-auto-rebar: build clean-core-compat-auto-rebar
+
+	$i "Bootstrap a new OTP library named $(APP)"
+	$t mkdir $(APP)/
+	$t cp ../erlang.mk $(APP)/
+	$t $(MAKE) -C $(APP) -f erlang.mk bootstrap-lib $v
+
+	$i "Add rebar.config as a dependency of 'app' target"
+	$t echo "app:: rebar.config" >> $(APP)/Makefile
+
+	$i "Build the application"
+	$t $(MAKE) -C $(APP) $v
+
+	$i "Check that rebar.config was created"
+	$t test -f $(APP)/rebar.config
+
+	$i "Check that rebar.config can be loaded"
+	$t $(ERL) -eval "{ok, _} = file:consult(\"$(APP)/rebar.config\"), halt()"
+
+	$i "Create a temporary file"
+	$t touch $(APP)/older_file
+
+	$i "Wait a second"
+	$t sleep 1
+
+	$i "Build the application again"
+	$t $(MAKE) -C $(APP) $v
+
+	$i "Check that rebar.config is newer than the temporary file"
+	$t test $(APP)/rebar.config -nt $(APP)/older_file
+
+	$i "Check that rebar.config can be loaded"
+	$t $(ERL) -eval "{ok, _} = file:consult(\"$(APP)/rebar.config\"), halt()"
+
+core-compat-rebar: build clean-core-compat-rebar
+
+	$i "Bootstrap a new OTP library named $(APP)"
+	$t mkdir $(APP)/
+	$t cp ../erlang.mk $(APP)/
+	$t $(MAKE) -C $(APP) -f erlang.mk bootstrap-lib $v
+
+	$i "Run 'make rebar.config'"
+	$t $(MAKE) -C $(APP) rebar.config $v
+
+	$i "Check that rebar.config was created"
+	$t test -f $(APP)/rebar.config
+
+	$i "Check that rebar.config can be loaded"
+	$t $(ERL) -eval "{ok, _} = file:consult(\"$(APP)/rebar.config\"), halt()"
+
+	$i "Create a temporary file"
+	$t touch $(APP)/older_file
+
+	$i "Wait a second"
+	$t sleep 1
+
+	$i "Run 'make rebar.config' again"
+	$t $(MAKE) -C $(APP) rebar.config $v
+
+	$i "Check that rebar.config is newer than the temporary file"
+	$t test $(APP)/rebar.config -nt $(APP)/older_file
+
+	$i "Check that rebar.config can be loaded"
+	$t $(ERL) -eval "{ok, _} = file:consult(\"$(APP)/rebar.config\"), halt()"
+
+core-compat-rebar-deps: build clean-core-compat-rebar-deps
+
+	$i "Bootstrap a new OTP library named $(APP)"
+	$t mkdir $(APP)/
+	$t cp ../erlang.mk $(APP)/
+	$t $(MAKE) -C $(APP) -f erlang.mk bootstrap-lib $v
+
+	$i "Add Cowboy as a dependency"
+	$t sed -i.bak '2i\
+DEPS = cowboy\
+dep_cowboy = git repo commit\
+' $(APP)/Makefile
+
+	$i "Run 'make rebar.config'"
+	$t $(MAKE) -C $(APP) rebar.config $v
+
+	$i "Check that rebar.config was created"
+	$t test -f $(APP)/rebar.config
+
+	$i "Check that Cowboy is listed in rebar.config"
+	$t $(ERL) -eval " \
+		{ok, C} = file:consult(\"$(APP)/rebar.config\"), \
+		{_, [{cowboy, _, {git, \"repo\", \"commit\"}}]} = lists:keyfind(deps, 1, C), \
+		halt()"
+
+core-compat-rebar-deps-pkg: build clean-core-compat-rebar-deps-pkg
+
+	$i "Bootstrap a new OTP library named $(APP)"
+	$t mkdir $(APP)/
+	$t cp ../erlang.mk $(APP)/
+	$t $(MAKE) -C $(APP) -f erlang.mk bootstrap-lib $v
+
+	$i "Add Cowboy package as a dependency"
+	$t sed -i.bak '2i\
+DEPS = cowboy\
+' $(APP)/Makefile
+
+	$i "Run 'make rebar.config'"
+	$t $(MAKE) -C $(APP) rebar.config $v
+
+	$i "Check that rebar.config was created"
+	$t test -f $(APP)/rebar.config
+
+	$i "Check that Cowboy is listed in rebar.config"
+	$t $(ERL) -eval " \
+		{ok, C} = file:consult(\"$(APP)/rebar.config\"), \
+		{_, [{cowboy, _, {git, \"https://github.com/\" ++ _, _}}]} = lists:keyfind(deps, 1, C), \
+		halt()"
+
+core-compat-rebar-erlc-opts: build clean-core-compat-rebar-erlc-opts
+
+	$i "Bootstrap a new OTP library named $(APP)"
+	$t mkdir $(APP)/
+	$t cp ../erlang.mk $(APP)/
+	$t $(MAKE) -C $(APP) -f erlang.mk bootstrap-lib $v
+
+	$i "Add extra options to ERLC_OPTS"
+	$t echo "ERLC_OPTS += +warn_export_all +warn_missing_spec +warn_untyped_record" >> $(APP)/Makefile
+
+	$i "Run 'make rebar.config'"
+	$t $(MAKE) -C $(APP) rebar.config $v
+
+	$i "Check that rebar.config was created"
+	$t test -f $(APP)/rebar.config
+
+	$i "Check that -Werror is not listed in rebar.config"
+	$t $(ERL) -eval " \
+		{ok, C} = file:consult(\"$(APP)/rebar.config\"), \
+		{_, Opts} = lists:keyfind(erl_opts, 1, C), \
+		false = lists:member(warning_as_errors, Opts), \
+		halt()"
+
+	$i "Check that debug_info is listed in rebar.config"
+	$t $(ERL) -eval " \
+		{ok, C} = file:consult(\"$(APP)/rebar.config\"), \
+		{_, Opts} = lists:keyfind(erl_opts, 1, C), \
+		true = lists:member(debug_info, Opts), \
+		halt()"
+
+	$i "Check that extra options are listed in rebar.config"
+	$t $(ERL) -eval " \
+		{ok, C} = file:consult(\"$(APP)/rebar.config\"), \
+		{_, Opts} = lists:keyfind(erl_opts, 1, C), \
+		true = lists:member(warn_export_all, Opts), \
+		true = lists:member(warn_missing_spec, Opts), \
+		true = lists:member(warn_untyped_record, Opts), \
+		halt()"