Merge pull request #1222 from jjh42/doc-error

Added more informative error to Makefile when ex_doc is not available.

Author: José Valim

.gitignore

@@ -14,3 +14,4 @@ erl_crash.dump
 .dialyzer_plt
 .dialyzer.base_plt
 .*.swp
+docs

Makefile

@@ -96,12 +96,15 @@ clean:
 
 SOURCE_REF = $(shell head="$$(git rev-parse HEAD)" tag="$$(git tag --points-at $$head | tail -1)" ; echo "$${tag:-$$head}\c")
 
-docs: compile
+docs: compile ../ex_doc/bin/ex_doc
 	mkdir -p ebin
 	rm -rf docs
 	cp -R -f lib/*/ebin/*.beam ./ebin
 	bin/elixir ../ex_doc/bin/ex_doc "Elixir" "$(VERSION)" -m Kernel -u "https://github.com/elixir-lang/elixir" --source-ref "$(call SOURCE_REF)"
-	rm -rf ebin
+
+../ex_doc/bin/ex_doc:
+	@ echo "ex_doc is not found in ../ex_doc as expected. See README for more information."
+	@ false
 
 release_zip: compile
 	rm -rf v$(VERSION).zip

README.md

@@ -20,6 +20,15 @@ However, if tests fail, it is likely you have an outdated Erlang version (Elixir
 
 If you have the correct version and tests still fail, feel free to [open an issue][2].
 
+## Building documentation
+
+Building the documentation requires [ex_doc](https://github.com/elixir-lang/ex_doc) to be installed and built in the same containing folder as elixir.
+
+    # After cloning and compiling Elixir
+    $ git clone git://github.com/elixir-lang/ex_doc.git
+    $ cd ../ex_doc && ../elixir/bin/mix compile
+    $ cd ../elixir && make docs
+
 ## Contributing
 
 We appreciate any contribution to Elixir, so check out our [CONTRIBUTING.md](CONTRIBUTING.md) guide for more information. We usually keep a list of features and bugs [in the issue tracker][2].