Merge pull request #2752 from fishcakez/dialyzer_warns

Fix some dialyzer warnings

Author: José Valim

Makefile

@@ -183,7 +183,7 @@ test_stdlib: compile
 
 #==> Dialyzer tasks
 
-DIALYZER_OPTS = --no_check_plt --fullpath -Werror_handling -Wunmatched_returns -Wrace_conditions -Wunderspecs
+DIALYZER_OPTS = --no_check_plt --fullpath -Werror_handling -Wunmatched_returns -Wunderspecs
 PLT = .elixir.plt
 
 $(PLT):

lib/elixir/lib/application.ex

@@ -201,7 +201,7 @@ defmodule Application do
   `:applications` in the `.app` file in case they were not previously
   started.
   """
-  @spec ensure_all_started(app, start_type) :: {:ok, [app]} | {:error, term}
+  @spec ensure_all_started(app, start_type) :: {:ok, [app]} | {:error, {app, term}}
   def ensure_all_started(app, type \\ :temporary) when is_atom(app) do
     :application.ensure_all_started(app, type)
   end

lib/elixir/lib/file.ex

@@ -75,6 +75,12 @@ defmodule File do
   @type posix :: :file.posix()
   @type io_device :: :file.io_device()
   @type stat_options :: [time: :local | :universal | :posix]
+  @type mode :: :append | :binary | :compressed | :delayed_write | :exclusive |
+    :raw | :read | :read_ahead | :sync | :write |
+    {:encoding , :latin1 | :unicode | :utf16 | :utf32 | :utf8 |
+      {:utf16, :big | :little} | {:utf32, :big | :little}} |
+    {:read_ahead, pos_integer} |
+    {:delayed_write, non_neg_integer, non_neg_integer}
 
   @doc """
   Returns `true` if the path is a regular file.
@@ -612,15 +618,15 @@ defmodule File do
 
   Check `File.open/2` for other available options.
   """
-  @spec write(Path.t, iodata, list) :: :ok | {:error, posix}
+  @spec write(Path.t, iodata, [mode]) :: :ok | {:error, posix}
   def write(path, content, modes \\ []) do
     F.write_file(IO.chardata_to_string(path), content, modes)
   end
 
   @doc """
   Same as `write/3` but raises an exception if it fails, returns `:ok` otherwise.
   """
-  @spec write!(Path.t, iodata, list) :: :ok | no_return
+  @spec write!(Path.t, iodata, [mode]) :: :ok | no_return
   def write!(path, content, modes \\ []) do
     path = IO.chardata_to_string(path)
     case F.write_file(path, content, modes) do
@@ -902,7 +908,8 @@ defmodule File do
       File.close(file)
 
   """
-  @spec open(Path.t, list) :: {:ok, io_device} | {:error, posix}
+  @spec open(Path.t, [mode | :ram]) :: {:ok, io_device} | {:error, posix}
+  @spec open(Path.t, (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
   def open(path, modes \\ [])
 
   def open(path, modes) when is_list(modes) do
@@ -935,7 +942,7 @@ defmodule File do
       end)
 
   """
-  @spec open(Path.t, list, (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
+  @spec open(Path.t, [mode | :ram], (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
   def open(path, modes, function) do
     case open(path, modes) do
       {:ok, device} ->
@@ -953,7 +960,7 @@ defmodule File do
 
   Returns the `io_device` otherwise.
   """
-  @spec open!(Path.t, list) :: io_device | no_return
+  @spec open!(Path.t, [mode]) :: io_device | no_return
   def open!(path, modes \\ []) do
     path = IO.chardata_to_string(path)
     case open(path, modes) do
@@ -968,7 +975,7 @@ defmodule File do
 
   Returns the function result otherwise.
   """
-  @spec open!(Path.t, list, (io_device -> res)) :: res | no_return when res: var
+  @spec open!(Path.t, [mode | :ram], (io_device -> res)) :: res | no_return when res: var
   def open!(path, modes, function) do
     path = IO.chardata_to_string(path)
     case open(path, modes, function) do
@@ -1124,15 +1131,15 @@ defmodule File do
   Returns `:ok` on success, or `{:error, reason}`
   on failure.
   """
-  @spec chmod(Path.t, integer) :: :ok | {:error, posix}
+  @spec chmod(Path.t, non_neg_integer) :: :ok | {:error, posix}
   def chmod(path, mode) do
     F.change_mode(IO.chardata_to_string(path), mode)
   end
 
   @doc """
   Same as `chmod/2`, but raises an exception in case of failure. Otherwise `:ok`.
   """
-  @spec chmod!(Path.t, integer) :: :ok | no_return
+  @spec chmod!(Path.t, non_neg_integer) :: :ok | no_return
   def chmod!(path, mode) do
     path = IO.chardata_to_string(path)
     case chmod(path, mode) do
@@ -1147,15 +1154,15 @@ defmodule File do
   for a given `file`. Returns `:ok` on success, or
   `{:error, reason}` on failure.
   """
-  @spec chgrp(Path.t, integer) :: :ok | {:error, posix}
+  @spec chgrp(Path.t, non_neg_integer) :: :ok | {:error, posix}
   def chgrp(path, gid) do
     F.change_group(IO.chardata_to_string(path), gid)
   end
 
   @doc """
   Same as `chgrp/2`, but raises an exception in case of failure. Otherwise `:ok`.
   """
-  @spec chgrp!(Path.t, integer) :: :ok | no_return
+  @spec chgrp!(Path.t, non_neg_integer) :: :ok | no_return
   def chgrp!(path, gid) do
     path = IO.chardata_to_string(path)
     case chgrp(path, gid) do
@@ -1170,15 +1177,15 @@ defmodule File do
   for a given `file`. Returns `:ok` on success,
   or `{:error, reason}` on failure.
   """
-  @spec chown(Path.t, integer) :: :ok | {:error, posix}
+  @spec chown(Path.t, non_neg_integer) :: :ok | {:error, posix}
   def chown(path, uid) do
     F.change_owner(IO.chardata_to_string(path), uid)
   end
 
   @doc """
   Same as `chown/2`, but raises an exception in case of failure. Otherwise `:ok`.
   """
-  @spec chown!(Path.t, integer) :: :ok | no_return
+  @spec chown!(Path.t, non_neg_integer) :: :ok | no_return
   def chown!(path, uid) do
     path = IO.chardata_to_string(path)
     case chown(path, uid) do

lib/elixir/lib/gen_event.ex

@@ -678,7 +678,7 @@ defmodule GenEvent do
 
   @doc false
   def system_replace_state(fun, [name, handlers, hib]) do
-    {handlers, states} =
+    [handlers, states] =
       List.unzip(for handler <- handlers do
         handler(module: mod, id: id, state: state) = handler
         cur = {mod, id, state}

lib/elixir/lib/gen_event/stream.ex

@@ -150,7 +150,7 @@ defimpl Enumerable, for: GenEvent.Stream do
   # If we reach this branch, the handler was not removed yet,
   # so we trigger a request for doing so.
   defp stop(stream, {pid, ref, _} = acc) do
-    Task.start(fn -> GenEvent.remove_handler(pid, {GenEvent.Stream, ref}, :shutdown) end)
+    _ = Task.start(fn -> GenEvent.remove_handler(pid, {GenEvent.Stream, ref}, :shutdown) end)
     stop(stream, {:removed, acc})
   end
 

lib/elixir/lib/inspect/algebra.ex

@@ -482,7 +482,7 @@ defmodule Inspect.Algebra do
   and returns an IO data representation of the best layout for the
   document to fit in the given width.
   """
-  @spec format(t, non_neg_integer | :infinity) :: binary
+  @spec format(t, non_neg_integer | :infinity) :: iodata
   def format(d, w) do
     format(w, 0, [{0, default_mode(w), doc_group(d)}])
   end

lib/elixir/lib/integer.ex

@@ -111,7 +111,7 @@ defmodule Integer do
       "64"
 
   """
-  @spec to_string(integer, pos_integer) :: String.t
+  @spec to_string(integer, 2..36) :: String.t
   def to_string(some_integer, base) do
     :erlang.integer_to_binary(some_integer, base)
   end
@@ -144,7 +144,7 @@ defmodule Integer do
       '3FF'
 
   """
-  @spec to_char_list(integer, pos_integer) :: char_list
+  @spec to_char_list(integer, 2..36) :: char_list
   def to_char_list(number, base) do
     :erlang.integer_to_list(number, base)
   end

lib/elixir/lib/kernel.ex

@@ -2384,7 +2384,7 @@ defmodule Kernel do
   it is not loaded. Check `Code.ensure_loaded/1` for more
   information.
   """
-  @spec function_exported?(atom | tuple, atom, integer) :: boolean
+  @spec function_exported?(atom | tuple, atom, arity) :: boolean
   def function_exported?(module, function, arity) do
     :erlang.function_exported(module, function, arity)
   end

lib/elixir/lib/kernel/cli.ex

@@ -408,7 +408,7 @@ defmodule Kernel.CLI do
   end
 
   defp wrapper(fun) do
-    fun.()
+    _ = fun.()
     :ok
   end
 

lib/elixir/lib/keyword.ex

@@ -136,7 +136,7 @@ defmodule Keyword do
       :error
 
   """
-  @spec fetch(t, key) :: {:ok, value}
+  @spec fetch(t, key) :: {:ok, value} | :error
   def fetch(keywords, key) when is_list(keywords) and is_atom(key) do
     case :lists.keyfind(key, 1, keywords) do
       {^key, value} -> {:ok, value}