Allow elixirc_paths to also be given through the command line

Once given, the command line overrides the project
configuration in `mix compile.elixir`.

Closes #2557

Author: José Valim

CHANGELOG.md

@@ -9,6 +9,7 @@
   * [Map] Add `Map.from_struct/1`
   * [Mix] Allow `--app` flag to be passed to `mix new`
   * [Mix] Support lowercase `http(s)_proxy` environment variables
+  * [Mix] Allow `elixirc_paths` to also be given through the command line to `mix compile.elixir`
   * [String] `String.slice/2` and `String.slice/3` have been optimized
 
 * Bug fixes
@@ -17,7 +18,7 @@
   * [Kernel] Correctly parse unary/binary operators regardless of number of spaces
   * [Kernel] Ensure private functions are not exported
   * [Protocol] Do not expose protocol convention on `assert_impl!/2`
-  * [Regex] Do not consider subpatterns on `Regex.split/3`
+  * [Regex] Do not consider include captures on `Regex.split/3` results
   * [Stream] Implement the `Inspect` protocol for Streams so we do not leak the Stream representation
 
 * Deprecations
@@ -34,6 +35,7 @@
 
 * Backwards incompatible changes
   * [Kernel] `binding/1` and `binding/2` expecting a list were removed
+  * [Regex] Do not consider include captures on `Regex.split/3` results
 
 ## v0.14.3 (2014-07-12)
 

lib/mix/lib/mix/tasks/compile.elixir.ex

@@ -22,6 +22,8 @@ defmodule Mix.Tasks.Compile.Elixir do
     * `--debug-info` (`--no-debug-info`) - attach (or not) debug info to compiled modules
     * `--ignore-module-conflict` - do not emit warnings if a module was previously defined
     * `--warnings-as-errors` - treat warnings as errors and return a non-zero exit code
+    * `--elixirc-paths` - paths to lookup for Elixir source.
+      Can be given multiple times and, once given, overrides the project elixirc_paths config.
 
   ## Configuration
 
@@ -37,7 +39,8 @@ defmodule Mix.Tasks.Compile.Elixir do
   """
 
   @switches [force: :boolean, docs: :boolean, warnings_as_errors: :boolean,
-             ignore_module_conflict: :boolean, debug_info: :boolean]
+             ignore_module_conflict: :boolean, debug_info: :boolean,
+             elixirc_paths: :keep]
 
   @doc """
   Runs this task.
@@ -46,8 +49,11 @@ defmodule Mix.Tasks.Compile.Elixir do
     {opts, _, _} = OptionParser.parse(args, switches: @switches)
 
     project = Mix.Project.config
-    srcs = project[:elixirc_paths]
     dest = Mix.Project.compile_path(project)
+    srcs = case Keyword.get_values(opts, :elixirc_paths) do
+      [] -> project[:elixirc_paths]
+      ep -> ep
+    end
 
     manifest = manifest()
     configs  = Mix.Project.config_files ++ Mix.Tasks.Compile.Erlang.manifests

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -180,6 +180,9 @@ defmodule Mix.Tasks.Compile.ElixirTest do
       # Nothing to compile with the custom source paths
       assert Mix.Tasks.Compile.Elixir.run([])
       refute_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
+
+      assert Mix.Tasks.Compile.Elixir.run(["--elixirc-paths", "lib"])
+      assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
     end
   end
 end