Improve error messages when something goes wrong #5388
Description
Environment
- Elixir version (elixir -v):
Erlang/OTP 19 [erts-8.1] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Elixir 1.3.4
- Operating system:
masOS Sierra 10.12
Current behavior
I'm making an umbrella app and I'm using env variables to set a few parameters I need to tweak for my builds in all the apps of the project. Here's an example :
def project do
[app: :auth,
version: "0.1.0",
build_path: System.get_env("BUILD_PATH"),
config_path: "../../config/config.exs",
deps_path: System.get_env("DEPS_PATH"),
lockfile: "../../mix.lock",
elixir: "~> 1.3",
elixirc_paths: elixirc_paths(Mix.env),
compilers: [:phoenix, :gettext] ++ Mix.compilers,
build_embedded: Mix.env == :prod,
start_permanent: Mix.env == :prod,
aliases: aliases(),
deps: deps()]
end
If some parameters in the mix.exs file are wrong (I have tried with build_pathand config_path so far), the error messages aren't helping at all to debug why an exception is raised.
If no build_path and deps_path are set we get :
$> mix deps.get
** (FunctionClauseError) no function clause matching in IO.chardata_to_string/1
(elixir) lib/io.ex:412: IO.chardata_to_string(nil)
(elixir) lib/path.ex:619: Path.expand_home/1
(elixir) lib/path.ex:139: Path.expand/1
(mix) lib/mix/project.ex:83: Mix.Project.deps_config/1
(mix) lib/mix/dep.ex:167: Mix.Dep.in_dependency/3
(mix) lib/mix/dep/loader.ex:55: Mix.Dep.Loader.load/2
(mix) lib/mix/dep/converger.ex:179: Mix.Dep.Converger.all/9
(mix) lib/mix/dep/converger.ex:114: Mix.Dep.Converger.all/7
If build_path and deps_path are set, but with invalid directories, we get :
$> mix deps.get
Running dependency resolution
Dependency resolution completed
base64url: 0.0.1
comeonin: 2.6.0
connection: 1.0.4
cowboy: 1.0.4
cowlib: 1.0.2
db_connection: 1.0.0
decimal: 1.2.0
ecto: 2.0.5
ex_machina: 1.0.2
fs: 0.9.2
gettext: 0.12.1
guardian: 0.13.0
jose: 1.8.0
mime: 1.0.1
phoenix: 1.2.1
phoenix_ecto: 3.0.1
phoenix_html: 2.7.0
phoenix_live_reload: 1.0.0
phoenix_pubsub: 1.0.1
plug: 1.2.2
poison: 2.2.0
poolboy: 1.5.1
postgrex: 0.12.1
ranch: 1.2.1
uuid: 1.1.5
* Getting phoenix (Hex package)
Checking package (https://repo.hex.pm/tarballs/phoenix-1.2.1.tar)
Fetched package
** (exit) an exception was raised:
** (MatchError) no match of right hand side value: {:error, :enoent}
(stdlib) erl_tar.erl:870: :erl_tar.write_file/2
(stdlib) erl_tar.erl:810: :erl_tar.write_extracted_element/3
(stdlib) erl_tar.erl:598: :erl_tar.extract1/4
(stdlib) erl_tar.erl:571: :erl_tar.foldl_read1/4
(stdlib) erl_tar.erl:554: :erl_tar.foldl_read0/4
(stdlib) erl_tar.erl:546: :erl_tar.foldl_read/4
(hex) lib/hex/tar.ex:95: Hex.Tar.extract_contents/3
(hex) lib/hex/tar.ex:44: Hex.Tar.unpack/3
(stdlib) erl_tar.erl:556: :erl_tar.foldl_read0/4
(stdlib) erl_tar.erl:546: :erl_tar.foldl_read/4
(hex) lib/hex/tar.ex:95: Hex.Tar.extract_contents/3
(hex) lib/hex/tar.ex:44: Hex.Tar.unpack/3
(hex) lib/hex/scm.ex:110: Hex.SCM.checkout/1
(mix) lib/mix/dep/fetcher.ex:64: Mix.Dep.Fetcher.do_fetch/3
(mix) lib/mix/dep/converger.ex:174: Mix.Dep.Converger.all/9
(mix) lib/mix/dep/converger.ex:183: Mix.Dep.Converger.all/9
Expected behavior
Expecting mix to have an overall better errors/exceptions handling, and to eventually be able to explicitly point out what's wrong in the configuration file (in the case it's a configuration issue like here).
I know i'm only doing a reporting without having investigate in the code or came up with a pull request for this already, I'd like to, but don't have the time right now, sorry about that. Maybe later if you guys don't have worked on this yet.