Always compile project if task cannot be found

Closes #2704.

Author: ericmj

CHANGELOG.md

@@ -14,6 +14,7 @@
   * [GenServer] Do not deliver out of order messages on `GenServer.cast/2` on distributed mode
   * [Mix] Do not pre-compile a Mix project if an alias was found
   * [Mix] Properly handle compilation errors in the Erlang compiler
+  * [Mix] Always try to compile project if task cannot be found
 
 * Deprecations
   * [Collectable] Deprecate `Collectable.empty/1` and `Enum.traverse/2`

lib/mix/lib/mix/cli.ex

@@ -52,19 +52,7 @@ defmodule Mix.CLI do
   defp run_task(name, args) do
     try do
       Mix.Task.run "loadconfig"
-
-      # If the task is not available, let's try to
-      # compile the repository and then run it again.
-      cond do
-        Mix.Task.get(name) || Mix.Task.alias?(name) ->
-          Mix.Task.run(name, args)
-        Mix.Project.get ->
-          Mix.Task.run("compile")
-          Mix.Task.run(name, args)
-        true ->
-          # Raise no task error
-          Mix.Task.get!(name)
-      end
+      Mix.Task.run name, args
     rescue
       # We only rescue exceptions in the mix namespace, all
       # others pass through and will explode on the users face

lib/mix/lib/mix/task.ex

@@ -244,7 +244,13 @@ defmodule Mix.Task do
   end
 
   defp run_task(proj, task, args) do
-    module = get!(task)
+    module = get(task)
+
+    # If the task is not available, let's try to compile the project
+    unless module do
+      if proj, do: Mix.Task.run("compile")
+      module = get!(task)
+    end
 
     if recursive(module) and Mix.Project.umbrella? and Mix.ProjectStack.enable_recursion do
       res = recur(fn _ -> run(task, args) end)

lib/mix/test/mix/task_test.exs

@@ -3,6 +3,12 @@ Code.require_file "../test_helper.exs", __DIR__
 defmodule Mix.TaskTest do
   use MixTest.Case
 
+  defmodule SampleProject do
+    def project do
+      [app: :sample, version: "0.0.1"]
+    end
+  end
+
   test "run/1" do
     assert Mix.Task.run("hello") == "Hello, World!"
     assert Mix.Task.run("hello") == :noop
@@ -16,6 +22,17 @@ defmodule Mix.TaskTest do
     end
   end
 
+  test "try to compile if task is missing" do
+    Mix.Project.push(SampleProject, "sample")
+
+    assert_raise Mix.NoTaskError, fn ->
+      Mix.Task.run("unknown")
+    end
+
+    # Check if compile task have run
+    refute Mix.TasksServer.run({:task, "compile", Mix.Project.get})
+  end
+
   test "clear/0" do
     assert Mix.Task.run("hello") == "Hello, World!"
     Mix.Task.clear