core/deps-tools.mk: New targets `fetch-deps` and `list-deps`

.. to fetch and list deps recurvively.

Therefore, they work on direct dependencies, dependencies' dependencies,
and so on. Nothing is built with those targets.

The following targets are also available to work on other kinds of
dependencies:
    make fetch-doc-deps
    make fetch-rel-deps
    make fetch-test-deps
    make fetch-shell-deps
    make list-doc-deps
    make list-rel-deps
    make list-test-deps
    make list-shell-deps

In all cases, they include "normal" and eg. "test" dependencies of the
top-level project, then only "normal" dependencies' dependencies.

It's possible to include several kinds in one go:
    make fetch-deps DEP_TYPES='doc test'
    make list-deps DEP_TYPES='doc test'

As it may be difficult to use the output of `make list-*` because
the list could appear after other targets output (like dependencies
fetching), the list is available in files pointed by the following
variables:
    $(ERLANG_MK_RECURSIVE_DEPS_LIST)
    $(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST)
    $(ERLANG_MK_RECURSIVE_REL_DEPS_LIST)
    $(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST)
    $(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST)

Internally, `list-deps` is simply implemented on top of `fetch-deps`:
the latter fills a sorted log with all the directories it traversed.
`list-deps` finally just prints the log file to stdout.

Fixes #560.

3 files changed, 116 insertions, 0 deletions

diff --git a/core/core.mk b/core/core.mk
index 517ad18..167b1a1 100644
--- a/core/core.mk
+++ b/core/core.mk
@@ -121,6 +121,8 @@ help::
 		"  all           Run deps, app and rel targets in that order" \
 		"  app           Compile the project" \
 		"  deps          Fetch dependencies (if needed) and compile them" \
+		"  fetch-deps    Fetch dependencies recursively (if needed) without compiling them" \
+		"  list-deps     List dependencies recursively on stdout" \
 		"  search q=...  Search for a package in the built-in index" \
 		"  rel           Build a release for this project, if applicable" \
 		"  docs          Build the documentation for this project" \
diff --git a/core/deps-tools.mk b/core/deps-tools.mk
new file mode 100644
index 0000000..d0b5203
--- /dev/null
+++ b/core/deps-tools.mk
@@ -0,0 +1,105 @@
+# Copyright (c) 2013-2015, Loïc Hoguin <[email protected]>
+# Copyright (c) 2015-2016, Jean-Sébastien Pédron <[email protected]>
+# This file is part of erlang.mk and subject to the terms of the ISC License.
+
+# Fetch dependencies recursively (without building them).
+
+.PHONY: fetch-deps fetch-doc-deps fetch-rel-deps fetch-test-deps \
+	fetch-shell-deps
+
+.PHONY: $(ERLANG_MK_RECURSIVE_DEPS_LIST) \
+	$(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST) \
+	$(ERLANG_MK_RECURSIVE_REL_DEPS_LIST) \
+	$(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST) \
+	$(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST)
+
+fetch-deps: $(ERLANG_MK_RECURSIVE_DEPS_LIST)
+fetch-doc-deps: $(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST)
+fetch-rel-deps: $(ERLANG_MK_RECURSIVE_REL_DEPS_LIST)
+fetch-test-deps: $(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST)
+fetch-shell-deps: $(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST)
+
+ifneq ($(SKIP_DEPS),)
+$(ERLANG_MK_RECURSIVE_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_REL_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST):
+	$(verbose) :> $@
+else
+# By default, we fetch "normal" dependencies. They are also included no
+# matter the type of requested dependencies.
+#
+# $(ALL_DEPS_DIRS) includes $(BUILD_DEPS).
+
+$(ERLANG_MK_RECURSIVE_DEPS_LIST): $(ALL_DEPS_DIRS)
+$(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST): $(ALL_DEPS_DIRS) $(ALL_DOC_DEPS_DIRS)
+$(ERLANG_MK_RECURSIVE_REL_DEPS_LIST): $(ALL_DEPS_DIRS) $(ALL_REL_DEPS_DIRS)
+$(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST): $(ALL_DEPS_DIRS) $(ALL_TEST_DEPS_DIRS)
+$(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST): $(ALL_DEPS_DIRS) $(ALL_SHELL_DEPS_DIRS)
+
+# Allow to use fetch-deps and $(DEP_TYPES) to fetch multiple types of
+# dependencies with a single target.
+ifneq ($(filter doc,$(DEP_TYPES)),)
+$(ERLANG_MK_RECURSIVE_DEPS_LIST): $(ALL_DOC_DEPS_DIRS)
+endif
+ifneq ($(filter rel,$(DEP_TYPES)),)
+$(ERLANG_MK_RECURSIVE_DEPS_LIST): $(ALL_REL_DEPS_DIRS)
+endif
+ifneq ($(filter test,$(DEP_TYPES)),)
+$(ERLANG_MK_RECURSIVE_DEPS_LIST): $(ALL_TEST_DEPS_DIRS)
+endif
+ifneq ($(filter shell,$(DEP_TYPES)),)
+$(ERLANG_MK_RECURSIVE_DEPS_LIST): $(ALL_SHELL_DEPS_DIRS)
+endif
+
+ERLANG_MK_RECURSIVE_TMP_LIST := $(abspath $(ERLANG_MK_TMP)/recursive-tmp-deps.log)
+
+$(ERLANG_MK_RECURSIVE_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_REL_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST) \
+$(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST):
+ifeq ($(IS_APP)$(IS_DEP),)
+	$(verbose) mkdir -p $(ERLANG_MK_TMP)
+	$(verbose) rm -f $(ERLANG_MK_RECURSIVE_TMP_LIST)
+endif
+ifndef IS_APP
+	$(verbose) for dep in $(ALL_APPS_DIRS) ; do \
+		$(MAKE) -C $$dep $@ \
+		 IS_APP=1 \
+		 ERLANG_MK_RECURSIVE_TMP_LIST=$(ERLANG_MK_RECURSIVE_TMP_LIST) \
+		 || exit $$?; \
+	done
+endif
+	$(verbose) for dep in $^ ; do \
+		if ! grep -qs ^$$dep$$ $(ERLANG_MK_RECURSIVE_TMP_LIST); then \
+			echo $$dep >> $(ERLANG_MK_RECURSIVE_TMP_LIST); \
+			if grep -qs -E "^[[:blank:]]*include[[:blank:]]+(erlang\.mk|.*/erlang\.mk)$$" \
+			 $$dep/GNUmakefile $$dep/makefile $$dep/Makefile; then \
+				$(MAKE) -C $$dep fetch-deps \
+				 IS_DEP=1 \
+				 ERLANG_MK_RECURSIVE_TMP_LIST=$(ERLANG_MK_RECURSIVE_TMP_LIST) \
+				 || exit $$?; \
+			fi \
+		fi \
+	done
+ifeq ($(IS_APP)$(IS_DEP),)
+	$(verbose) sort < $(ERLANG_MK_RECURSIVE_TMP_LIST) | uniq > $@
+	$(verbose) rm $(ERLANG_MK_RECURSIVE_TMP_LIST)
+endif
+endif # ifneq ($(SKIP_DEPS),)
+
+# List dependencies recursively.
+
+.PHONY: list-deps list-doc-deps list-rel-deps list-test-deps \
+	list-shell-deps
+
+list-deps: $(ERLANG_MK_RECURSIVE_DEPS_LIST)
+list-doc-deps: $(ERLANG_MK_RECURSIVE_DOC_DEPS_LIST)
+list-rel-deps: $(ERLANG_MK_RECURSIVE_REL_DEPS_LIST)
+list-test-deps: $(ERLANG_MK_RECURSIVE_TEST_DEPS_LIST)
+list-shell-deps: $(ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST)
+
+list-deps list-doc-deps list-rel-deps list-test-deps list-shell-deps:
+	$(verbose) cat $^
diff --git a/core/deps.mk b/core/deps.mk
index 2d2e372..2207592 100644
--- a/core/deps.mk
+++ b/core/deps.mk
@@ -603,6 +603,15 @@ distclean-deps:
 	$(gen_verbose) rm -rf $(DEPS_DIR)
 endif
 
+# Forward-declare variables used in core/deps-tools.mk. This is required
+# in case plugins use them.
+
+ERLANG_MK_RECURSIVE_DEPS_LIST = $(ERLANG_MK_TMP)/recursive-deps-list.log
+ERLANG_MK_RECURSIVE_DOC_DEPS_LIST = $(ERLANG_MK_TMP)/recursive-doc-deps-list.log
+ERLANG_MK_RECURSIVE_REL_DEPS_LIST = $(ERLANG_MK_TMP)/recursive-rel-deps-list.log
+ERLANG_MK_RECURSIVE_TEST_DEPS_LIST = $(ERLANG_MK_TMP)/recursive-test-deps-list.log
+ERLANG_MK_RECURSIVE_SHELL_DEPS_LIST = $(ERLANG_MK_TMP)/recursive-shell-deps-list.log
+
 # External plugins.
 
 DEP_PLUGINS ?=