enable dialyzer and fix warnings

Author: ananthakumaran

.github/workflows/ci.yml

@@ -21,6 +21,7 @@ jobs:
             otp: 24.1
             check_warnings: true
             check_format: true
+            dialyzer: true
     steps:
       - uses: actions/checkout@v2
       - uses: erlef/setup-elixir@v1
@@ -33,3 +34,21 @@ jobs:
       - run: mix compile --force --warnings-as-errors
         if: ${{ matrix.check_warnings }}
       - run: mix test --trace
+      - name: Restore PLT cache
+        uses: actions/cache@v2
+        if: ${{ matrix.dialyzer }}
+        id: plt_cache
+        with:
+          key: |
+            ${{ runner.os }}-${{ matrix.elixir }}-${{ matrix.otp }}-plt
+          restore-keys: |
+            ${{ runner.os }}-${{ matrix.elixir }}-${{ matrix.otp }}-plt
+          path: |
+            priv/plts
+      # Create PLTs if no cache was found
+      - name: Create PLTs
+        if: ${{ matrix.dialyzer && steps.plt_cache.outputs.cache-hit != 'true' }}
+        run: mix dialyzer --plt
+      - name: Run dialyzer
+        if: ${{ matrix.dialyzer }}
+        run: mix dialyzer

.gitignore

@@ -24,3 +24,6 @@ zstream-*.tar
 
 # Temporary files for e.g. tests.
 /tmp
+
+/priv/plts/*.plt
+/priv/plts/*.plt.hash

lib/zstream.ex

@@ -87,5 +87,6 @@ defmodule Zstream do
     * Doesn't support file which uses data descriptor header.
     * Doesn't support encrypted file.
   """
+  @spec zip(Enumerable.t()) :: Enumerable.t()
   defdelegate unzip(stream), to: Zstream.Unzip
 end

lib/zstream/decoder.ex

@@ -3,7 +3,7 @@ defmodule Zstream.Decoder do
 
   @callback init() :: term
 
-  @callback decode(chunk :: iodata, state :: term) :: {[{:data, iodata}], term}
+  @callback decode(chunk :: iodata, state :: term) :: {Enumerable.t(), term}
 
   @callback close(state :: term) :: iodata
 

lib/zstream/unzip.ex

@@ -133,26 +133,20 @@ defmodule Zstream.Unzip do
   def local_file_header(data, state) do
     data = IO.iodata_to_binary(data)
 
-    case parse_local_header(data) do
-      {:ok, local_header, rest} ->
-        {decoder, decoder_state} = Zstream.Decoder.init(local_header.compression_method)
+    {:ok, local_header, rest} = parse_local_header(data)
+    {decoder, decoder_state} = Zstream.Decoder.init(local_header.compression_method)
 
-        if bit_set?(local_header.general_purpose_bit_flag, 3) do
-          raise Error, "Zip files with data descriptor record are not supported"
-        end
-
-        execute_state_machine(rest, %{
-          state
-          | local_header: local_header,
-            next: :filename_extra_field,
-            decoder: decoder,
-            decoder_state: decoder_state
-        })
-
-      :done ->
-        state = %{state | next: :done}
-        {[], state}
+    if bit_set?(local_header.general_purpose_bit_flag, 3) do
+      raise Error, "Zip files with data descriptor record are not supported"
     end
+
+    execute_state_machine(rest, %{
+      state
+      | local_header: local_header,
+        next: :filename_extra_field,
+        decoder: decoder,
+        decoder_state: decoder_state
+    })
   end
 
   def filename_extra_field(data, state) do

lib/zstream/zip.ex

@@ -200,7 +200,7 @@ defmodule Zstream.Zip do
       if state.coder do
         _compressed = state.coder.close(state.coder_state)
         state = put_in(state.coder, nil)
-        put_in(state.coder_state, nil)
+        state = put_in(state.coder_state, nil)
         _encrypted = state.encryption_coder.close(state.encryption_coder_state)
         state = put_in(state.encryption_coder, nil)
         put_in(state.encryption_coder_state, nil)

mix.exs

@@ -15,7 +15,8 @@ defmodule Zstream.Mixfile do
       docs: docs(),
       dialyzer: [
         plt_add_deps: :transitive,
-        flags: [:unmatched_returns, :race_conditions, :error_handling, :underspecs]
+        flags: [:unmatched_returns, :race_conditions, :error_handling, :underspecs],
+        plt_file: {:no_warn, "priv/plts/dialyzer.plt"}
       ],
       deps: deps()
     ]
@@ -30,7 +31,8 @@ defmodule Zstream.Mixfile do
   defp deps do
     [
       {:temp, "~> 0.4", only: :test, runtime: false},
-      {:ex_doc, ">= 0.0.0", only: :dev, runtime: false}
+      {:ex_doc, ">= 0.0.0", only: :dev, runtime: false},
+      {:dialyxir, "~> 0.5", only: [:dev], runtime: false}
     ]
   end
 

mix.lock

@@ -1,4 +1,5 @@
 %{
+  "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], [], "hexpm", "6c32a70ed5d452c6650916555b1f96c79af5fc4bf286997f8b15f213de786f73"},
   "earmark": {:hex, :earmark, "1.4.3", "364ca2e9710f6bff494117dbbd53880d84bebb692dafc3a78eb50aa3183f2bfd", [:mix], [], "hexpm", "8cf8a291ebf1c7b9539e3cddb19e9cef066c2441b1640f13c34c1d3cfc825fec"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.12", "b245e875ec0a311a342320da0551da407d9d2b65d98f7a9597ae078615af3449", [:mix], [], "hexpm", "711e2cc4d64abb7d566d43f54b78f7dc129308a63bc103fbd88550d2174b3160"},
   "ex_doc": {:hex, :ex_doc, "0.24.2", "e4c26603830c1a2286dae45f4412a4d1980e1e89dc779fcd0181ed1d5a05c8d9", [:mix], [{:earmark_parser, "~> 1.4.0", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "e134e1d9e821b8d9e4244687fb2ace58d479b67b282de5158333b0d57c6fb7da"},