Fix target dependencies and enable parallel again

We can now use 'make -j 32' again. All tests pass. There might
be some issues left with the areas that are not fully tested
yet (some plugins).

A few changes in behavior:

* 'make app' will also do 'make deps' unless SKIP_DEPS is set.
  You can use 'make app-build' instead to just build the application.

* 'make rel' will also do 'make app' (and therefore deps). There
  are no alternative target to keep the old behavior at this time.

build.config

@@ -10,6 +10,7 @@ core/index
 core/deps
 
 # Plugins that must run before Erlang code gets compiled.
+plugins/erlydtl
 plugins/protobuffs
 
 # Core modules, continued.
@@ -28,7 +29,6 @@ plugins/ct
 plugins/dialyzer
 plugins/edoc
 plugins/elvis
-plugins/erlydtl
 plugins/escript
 plugins/eunit
 plugins/relx

core/core.mk

@@ -76,8 +76,6 @@ endif
 
 # Core targets.
 
-.NOTPARALLEL:
-
 all:: deps app rel
 
 # Noop to avoid a Make warning when there's nothing to do.

core/erlc.mk

@@ -45,10 +45,10 @@ ifneq ($(wildcard src/),)
 # Targets.
 
 ifeq ($(wildcard ebin/test),)
-app:: $(PROJECT).d
+app:: deps $(PROJECT).d
 	$(verbose) $(MAKE) --no-print-directory app-build
 else
-app:: clean $(PROJECT).d
+app:: clean deps $(PROJECT).d
 	$(verbose) $(MAKE) --no-print-directory app-build
 endif
 

doc/src/guide/app.asciidoc

@@ -46,13 +46,18 @@ up generating releases.
 
 ==== Application
 
-You can build your application specifically, without
-looking at handling dependencies or generating a release,
-by running the following command:
+You can build your application and dependencies without
+generating a release by running the following command:
 
 [source,bash]
 $ make app
 
+To build your application without touching dependencies
+at all, you can use the `SKIP_DEPS` variable:
+
+[source,bash]
+$ make app SKIP_DEPS=1
+
 This command is very useful if you have a lot of dependencies
 and develop on a machine with slow file access, like the
 Raspberry Pi and many other embedded devices.
@@ -76,22 +81,21 @@ in the next chapter.
 
 ==== Release
 
-You can generate the release, skipping the steps for building
-the application and dependencies, by running the following
-command:
+It is not possible to build the release without at least
+building the application itself, unless of course if there's
+no application to begin with.
+
+To generate the release, `make` will generally suffice with
+a normal Erlang.mk. A separate target is however available,
+and will take care of building the release, after building
+the application and all dependencies:
 
 [source,bash]
 $ make rel
 
-This command can be useful if nothing changed except the
-release configuration files.
-
 Consult the link:relx.asciidoc[Releases] chapter for more
 information about what releases are and how they are generated.
 
-Note that this command may fail if a required dependency
-is missing.
-
 === Application resource file
 
 When building your application, Erlang.mk will generate the

plugins/relx.mk

@@ -22,7 +22,7 @@ endif
 
 ifeq ($(IS_DEP),)
 ifneq ($(wildcard $(RELX_CONFIG)),)
-rel:: distclean-relx-rel relx-rel
+rel:: relx-rel
 endif
 endif
 
@@ -34,7 +34,7 @@ $(RELX):
 	$(gen_verbose) $(call core_http_get,$(RELX),$(RELX_URL))
 	$(verbose) chmod +x $(RELX)
 
-relx-rel: $(RELX) rel-deps
+relx-rel: $(RELX) rel-deps app
 	$(verbose) $(RELX) -c $(RELX_CONFIG) $(RELX_OPTS)
 
 distclean-relx-rel: