Return diagnostics from Kernel.ParallelCompiler

5 files changed, 117 insertions, 90 deletions

diff --git a/lib/elixir/lib/io.ex b/lib/elixir/lib/io.ex
index 351d8bc6f..a6ba705de 100644
--- a/lib/elixir/lib/io.ex
+++ b/lib/elixir/lib/io.ex
@@ -327,7 +327,7 @@ defmodule IO do
 
   def warn(message, []) do
     message = [to_chardata(message), ?\n]
-    :elixir_errors.print_warning(0, nil, message, message)
+    :elixir_errors.print_diagnostic(:warning, 0, nil, message, message)
   end
 
   def warn(message, %Macro.Env{} = env) do
@@ -357,7 +357,8 @@ defmodule IO do
     line = opts[:line]
     file = opts[:file]
 
-    :elixir_errors.print_warning(
+    :elixir_errors.print_diagnostic(
+      :warning,
       line || 0,
       file && List.to_string(file),
       message,
diff --git a/lib/elixir/lib/kernel/parallel_compiler.ex b/lib/elixir/lib/kernel/parallel_compiler.ex
index db02906f3..7b8c88e0b 100644
--- a/lib/elixir/lib/kernel/parallel_compiler.ex
+++ b/lib/elixir/lib/kernel/parallel_compiler.ex
@@ -5,15 +5,24 @@ defmodule Kernel.ParallelCompiler do
 
   @typedoc "The line. 0 indicates no line."
   @type line() :: non_neg_integer()
-  @type location() :: line() | {pos_integer(), column :: non_neg_integer}
-  @type warning() :: {file :: Path.t(), location(), message :: String.t()}
-  @type error() :: {file :: Path.t(), location(), message :: String.t()}
+  @type position() :: line() | {pos_integer(), column :: non_neg_integer}
+
+  @type diagnostic(severity) :: %{
+          file: Path.t(),
+          severity: severity,
+          message: String.t(),
+          position: position
+        }
 
   @type info :: %{
-          runtime_warnings: [warning],
-          compile_warnings: [warning]
+          runtime_warnings: [diagnostic(:warning)],
+          compile_warnings: [diagnostic(:warning)]
         }
 
+  # Deprecated types
+  @type warning() :: {file :: Path.t(), position(), message :: String.t()}
+  @type error() :: {file :: Path.t(), position(), message :: String.t()}
+
   @doc """
   Starts a task for parallel compilation.
 
@@ -62,17 +71,14 @@ defmodule Kernel.ParallelCompiler do
 
   It returns `{:ok, modules, warnings}` or `{:error, errors, warnings}`
   by default but we recommend using `return_maps: true` so it returns
-  a map as third element instead of a list of warnings. The map has the
-  shape of:
+  diagnostics as maps as well as a map of compilation information.
+  The map has the shape of:
 
       %{
         runtime_warnings: [warning],
         compile_warnings: [warning]
       }
 
-  Both errors and warnings are a list of three-element tuples containing
-  the file, line and the formatted error/warning.
-
   ## Options
 
     * `:each_file` - for each file compiled, invokes the callback passing the
@@ -109,12 +115,13 @@ defmodule Kernel.ParallelCompiler do
     * `:beam_timestamp` - the modification timestamp to give all BEAM files
 
     * `:return_maps` (since v1.15.0) - returns maps with information instead of
-      a list of warnings
+      a list of warnings and returns diagnostics as maps instead of tuples
 
   """
   @doc since: "1.6.0"
   @spec compile([Path.t()], keyword()) ::
-          {:ok, [atom], [warning] | info()} | {:error, [error], [warning] | info()}
+          {:ok, [atom], [warning] | info()}
+          | {:error, [error] | [diagnostic(:error)], [warning] | info()}
   def compile(files, options \\ []) when is_list(options) do
     spawn_workers(files, :compile, options)
   end
@@ -126,7 +133,8 @@ defmodule Kernel.ParallelCompiler do
   """
   @doc since: "1.6.0"
   @spec compile_to_path([Path.t()], Path.t(), keyword()) ::
-          {:ok, [atom], [warning] | info()} | {:error, [error], [warning] | info()}
+          {:ok, [atom], [warning] | info()}
+          | {:error, [error] | [diagnostic(:error)], [warning] | info()}
   def compile_to_path(files, path, options \\ []) when is_binary(path) and is_list(options) do
     spawn_workers(files, {:compile, path}, options)
   end
@@ -139,17 +147,14 @@ defmodule Kernel.ParallelCompiler do
 
   It returns `{:ok, modules, warnings}` or `{:error, errors, warnings}`
   by default but we recommend using `return_maps: true` so it returns
-  a map as third element instead of a list of warnings. The map has the
-  shape of:
+  diagnostics as maps as well as a map of compilation information.
+  The map has the shape of:
 
       %{
         runtime_warnings: [warning],
         compile_warnings: [warning]
       }
 
-  Both errors and warnings are a list of three-element tuples containing
-  the file, line and the formatted error/warning.
-
   ## Options
 
     * `:each_file` - for each file compiled, invokes the callback passing the
@@ -167,12 +172,17 @@ defmodule Kernel.ParallelCompiler do
   end
 
   @doc """
-  Prints a warning returned by the compiler.
+  Prints a diagnostic returned by the compiler into stderr.
   """
-  @doc since: "1.13.0"
-  @spec print_warning(warning) :: :ok
+  @doc since: "1.15.0"
+  def print_diagnostic(%{file: file, position: position, message: message, severity: severity}) do
+    :elixir_errors.print_diagnostic_no_capture(severity, position, file, message)
+  end
+
+  @doc false
+  # TODO: Deprecate me on Elixir v1.19
   def print_warning({file, location, warning}) do
-    :elixir_errors.print_warning_no_diagnostic(location, file, warning)
+    :elixir_errors.print_diagnostic_no_capture(:warning, location, file, warning)
   end
 
   @doc false
@@ -209,7 +219,8 @@ defmodule Kernel.ParallelCompiler do
             "Compilation failed due to warnings while using the --warnings-as-errors option"
 
           IO.puts(:stderr, message)
-          {:error, r_warnings ++ c_warnings, %{info | runtime_warnings: [], compile_warnings: []}}
+          errors = Enum.map(r_warnings ++ c_warnings, &Map.replace!(&1, :severity, :error))
+          {:error, errors, %{info | runtime_warnings: [], compile_warnings: []}}
 
         {{:ok, outcome, info}, _} ->
           beam_timestamp = Keyword.get(options, :beam_timestamp)
@@ -230,7 +241,12 @@ defmodule Kernel.ParallelCompiler do
     if Keyword.get(options, :return_maps, false) do
       {status, modules_or_errors, info}
     else
-      {status, modules_or_errors, info.runtime_warnings ++ info.compile_warnings}
+      to_tuples = &Enum.map(&1, fn diag -> {diag.file, diag.position, diag.message} end)
+
+      modules_or_errors =
+        if status == :ok, do: modules_or_errors, else: to_tuples.(modules_or_errors)
+
+      {status, modules_or_errors, to_tuples.(info.runtime_warnings ++ info.compile_warnings)}
     end
   end
 
@@ -633,19 +649,13 @@ defmodule Kernel.ParallelCompiler do
         state = %{state | timer_ref: timer_ref}
         spawn_workers(queue, spawned, waiting, files, result, warnings, errors, state)
 
-      {:diagnostic, type, file, location, message} ->
-        file = file && Path.absname(file)
-        message = :unicode.characters_to_binary(message)
+      {:diagnostic, %{severity: :warning} = diagnostic} ->
+        warnings = [diagnostic | warnings]
+        wait_for_messages(queue, spawned, waiting, files, result, warnings, errors, state)
 
-        case type do
-          :warning ->
-            warnings = [{file, location, message} | warnings]
-            wait_for_messages(queue, spawned, waiting, files, result, warnings, errors, state)
-
-          :error ->
-            errors = [{file, location, message} | errors]
-            wait_for_messages(queue, spawned, waiting, files, result, warnings, errors, state)
-        end
+      {:diagnostic, %{severity: :error} = diagnostic} ->
+        errors = [diagnostic | errors]
+        wait_for_messages(queue, spawned, waiting, files, result, warnings, errors, state)
 
       {:file_ok, child_pid, ref, file, lexical} ->
         state.each_file.(file, lexical)
@@ -816,7 +826,9 @@ defmodule Kernel.ParallelCompiler do
         "and that the modules they reference exist and are correctly named\n"
     )
 
-    for {file, _, description} <- deadlock, do: {Path.absname(file), nil, description}
+    for {file, _, description} <- deadlock do
+      %{severity: :error, file: Path.absname(file), position: nil, message: description}
+    end
   end
 
   defp terminate(files) do
@@ -842,7 +854,7 @@ defmodule Kernel.ParallelCompiler do
     line = get_line(file, reason, stack)
     file = Path.absname(file)
     message = :unicode.characters_to_binary(Kernel.CLI.format_error(kind, reason, stack))
-    {file, line || 0, message}
+    %{file: file, position: line || 0, message: message, severity: :error}
   end
 
   defp get_line(_file, %{line: line, column: column}, _stack)
diff --git a/lib/elixir/lib/module/parallel_checker.ex b/lib/elixir/lib/module/parallel_checker.ex
index 58a571a49..2e52a6b98 100644
--- a/lib/elixir/lib/module/parallel_checker.ex
+++ b/lib/elixir/lib/module/parallel_checker.ex
@@ -147,24 +147,21 @@ defmodule Module.ParallelChecker do
       spawn({self(), checker}, module, file)
     end
 
-    modules = :gen_server.call(checker, :start, :infinity)
-    collect_results(modules, [])
+    count = :gen_server.call(checker, :start, :infinity)
+    collect_results(count, [])
   end
 
-  defp collect_results([], warnings) do
-    warnings
+  defp collect_results(0, diagnostics) do
+    diagnostics
   end
 
-  defp collect_results(modules, warnings) do
+  defp collect_results(count, diagnostics) do
     receive do
-      {:diagnostic, _type, file, location, message} ->
-        file = file && Path.absname(file)
-        message = :unicode.characters_to_binary(message)
-        warning = {file, location, message}
-        collect_results(modules, [warning | warnings])
-
-      {__MODULE__, _module, new_warnings} ->
-        collect_results(tl(modules), new_warnings ++ warnings)
+      {:diagnostic, diagnostic} ->
+        collect_results(count, [diagnostic | diagnostics])
+
+      {__MODULE__, _module, new_diagnostics} ->
+        collect_results(count - 1, new_diagnostics ++ diagnostics)
     end
   end
 
@@ -294,10 +291,14 @@ defmodule Module.ParallelChecker do
   def emit_warnings(warnings) do
     Enum.flat_map(warnings, fn {module, warning, locations} ->
       message = module.format_warning(warning)
-      :elixir_errors.print_warning_no_diagnostic([message, ?\n, format_locations(locations)])
+
+      :elixir_errors.print_diagnostic_no_capture(
+        :warning,
+        [message, ?\n, format_locations(locations)]
+      )
 
       Enum.map(locations, fn {file, line, _mfa} ->
-        {file, line, message}
+        %{severity: :warning, file: file, position: line, message: message}
       end)
     end)
   end
@@ -485,7 +486,7 @@ defmodule Module.ParallelChecker do
       end
     end
 
-    {:reply, modules, run_checkers(state)}
+    {:reply, length(modules), run_checkers(state)}
   end
 
   def handle_call(:ets, _from, state) do
diff --git a/lib/elixir/src/elixir_errors.erl b/lib/elixir/src/elixir_errors.erl
index d3f5b28ef..758fffb67 100644
--- a/lib/elixir/src/elixir_errors.erl
+++ b/lib/elixir/src/elixir_errors.erl
@@ -7,7 +7,7 @@
 -export([compile_error/1, compile_error/3, parse_error/5]).
 -export([function_error/4, module_error/4, file_error/4]).
 -export([erl_warn/3, file_warn/4]).
--export([print_warning/4, print_warning_no_diagnostic/1, print_warning_no_diagnostic/3]).
+-export([print_diagnostic/5, print_diagnostic_no_capture/2, print_diagnostic_no_capture/4]).
 -include("elixir.hrl").
 -type location() :: non_neg_integer() | {non_neg_integer(), non_neg_integer()}.
 
@@ -17,21 +17,22 @@ erl_warn(none, File, Warning) ->
   erl_warn(0, File, Warning);
 erl_warn(Location, File, Warning) when is_binary(File) ->
   send_diagnostic(warning, Location, File, Warning),
-  print_warning_no_diagnostic(Location, File, Warning).
+  print_diagnostic_no_capture(warning, Location, File, Warning).
 
--spec print_warning_no_diagnostic(location(), unicode:chardata(), unicode:chardata()) -> ok.
-print_warning_no_diagnostic(Location, File, Warning) ->
-  print_warning_no_diagnostic([Warning, "\n  ", file_format(Location, File), $\n]).
+-spec print_diagnostic_no_capture(warning | error, location(), unicode:chardata(), unicode:chardata()) -> ok.
+print_diagnostic_no_capture(Type, Location, File, Message) ->
+  print_diagnostic_no_capture(Type, [Message, "\n  ", file_format(Location, File), $\n]).
 
--spec print_warning_no_diagnostic(unicode:chardata()) -> ok.
-print_warning_no_diagnostic(Message) ->
-  io:put_chars(standard_error, [warning_prefix(), Message, $\n]),
+-spec print_diagnostic_no_capture(warning | error, unicode:chardata()) -> ok.
+print_diagnostic_no_capture(Type, Message) ->
+  io:put_chars(standard_error, [prefix(Type), Message, $\n]),
   ok.
 
--spec print_warning(location(), unicode:chardata() | nil, unicode:chardata(), unicode:chardata()) -> ok.
-print_warning(Location, File, DiagMessage, PrintMessage) when is_binary(File) or (File == nil) ->
-  send_diagnostic(warning, Location, File, DiagMessage),
-  print_warning_no_diagnostic(PrintMessage).
+-spec print_diagnostic(warning | error, location(), unicode:chardata() | nil, unicode:chardata(), unicode:chardata()) -> ok.
+print_diagnostic(Type, Location, File, DiagMessage, PrintMessage)
+    when is_binary(File) or (File == nil) ->
+  send_diagnostic(Type, Location, File, DiagMessage),
+  print_diagnostic_no_capture(Type, PrintMessage).
 
 %% Compilation error/warn handling.
 
@@ -44,8 +45,8 @@ file_warn(Meta, E, Module, Desc) when is_list(Meta) ->
     true -> ok;
     false ->
       {EnvLine, EnvFile, EnvLocation} = env_format(Meta, E),
-      Warning = Module:format_error(Desc),
-      print_warning(EnvLine, EnvFile, Warning, [Warning, "\n  ", EnvLocation, $\n])
+      Message = Module:format_error(Desc),
+      print_diagnostic(warning, EnvLine, EnvFile, Message, [Message, "\n  ", EnvLocation, $\n])
   end.
 
 -spec file_error(list(), binary() | #{file := binary(), _ => _}, module(), any()) -> no_return().
@@ -78,8 +79,7 @@ function_error(Meta, Env, Module, Desc) ->
 print_error(Meta, Env, Module, Desc) ->
   {EnvLine, EnvFile, EnvLocation} = env_format(Meta, Env),
   Message = Module:format_error(Desc),
-  send_diagnostic(error, EnvLine, EnvFile, Message),
-  io:put_chars(standard_error, [error_prefix(), Message, "\n  ", EnvLocation, $\n, $\n]),
+  print_diagnostic(error, EnvLine, EnvFile, Message, [Message, "\n  ", EnvLocation, $\n]),
   ok.
 
 %% Compilation error.
@@ -210,20 +210,27 @@ snippet(InputString, Location, StartLine, StartColumn) ->
 
 %% Helpers
 
-send_diagnostic(Type, Line, File, Message) ->
+send_diagnostic(Severity, Position, File, Message) ->
   case get(elixir_compiler_info) of
     undefined -> ok;
-    {CompilerPid, _} -> CompilerPid ! {diagnostic, Type, File, Line, Message}
+    {CompilerPid, _} ->
+      Diagnostic = #{
+        severity => Severity,
+        file => if File =:= nil -> nil; true -> filename:absname(File) end,
+        position => Position,
+        message => unicode:characters_to_binary(Message)
+      },
+
+      CompilerPid ! {diagnostic, Diagnostic}
   end,
   ok.
 
-warning_prefix() ->
+prefix(warning) ->
   case application:get_env(elixir, ansi_enabled, false) of
     true -> <<"\e[33mwarning: \e[0m">>;
     false -> <<"warning: ">>
-  end.
-
-error_prefix() ->
+  end;
+prefix(error) ->
   case application:get_env(elixir, ansi_enabled, false) of
     true -> <<"\e[31merror: \e[0m">>;
     false -> <<"error: ">>
diff --git a/lib/mix/lib/mix/compilers/elixir.ex b/lib/mix/lib/mix/compilers/elixir.ex
index 8accc7cba..c4a48742a 100644
--- a/lib/mix/lib/mix/compilers/elixir.ex
+++ b/lib/mix/lib/mix/compilers/elixir.ex
@@ -1,7 +1,7 @@
 defmodule Mix.Compilers.Elixir do
   @moduledoc false
 
-  @manifest_vsn 18
+  @manifest_vsn 19
   @checkpoint_vsn 2
 
   import Record
@@ -190,14 +190,14 @@ defmodule Mix.Compilers.Elixir do
 
           put_compile_env(sources)
           info_warnings = info.runtime_warnings ++ info.compile_warnings
-          all_warnings = previous_warnings ++ Enum.map(info_warnings, &diagnostic(&1, :warning))
+          all_warnings = previous_warnings ++ Enum.map(info_warnings, &diagnostic/1)
           unless_previous_warnings_as_errors(previous_warnings, opts, {:ok, all_warnings})
 
         {:error, errors, %{runtime_warnings: r_warnings, compile_warnings: c_warnings}, state} ->
           # In case of errors, we show all previous warnings and all new ones.
           {_, _, sources, _, _} = state
-          errors = Enum.map(errors, &diagnostic(&1, :error))
-          warnings = Enum.map(r_warnings ++ c_warnings, &diagnostic(&1, :warning))
+          errors = Enum.map(errors, &diagnostic/1)
+          warnings = Enum.map(r_warnings ++ c_warnings, &diagnostic/1)
           all_warnings = Keyword.get(opts, :all_warnings, true)
           {:error, previous_warnings(sources, all_warnings) ++ warnings ++ errors}
       after
@@ -697,21 +697,27 @@ defmodule Mix.Compilers.Elixir do
           runtime_warnings: runtime_warnings
         ) <- sources,
         file = Path.absname(source),
-        {location, message} <- compile_warnings ++ runtime_warnings do
-      warning = {file, location, message}
+        {position, message} <- compile_warnings ++ runtime_warnings do
+      diagnostic = %Mix.Task.Compiler.Diagnostic{
+        severity: :warning,
+        file: file,
+        position: position,
+        message: message,
+        compiler_name: "Elixir"
+      }
 
       if print? do
         Mix.shell().print_app()
-        Kernel.ParallelCompiler.print_warning(warning)
+        Kernel.ParallelCompiler.print_diagnostic(diagnostic)
       end
 
-      diagnostic(warning, :warning)
+      diagnostic
     end
   end
 
   defp apply_warnings(sources, %{runtime_warnings: r_warnings, compile_warnings: c_warnings}) do
-    runtime_group = Enum.group_by(r_warnings, &elem(&1, 0), &{elem(&1, 1), elem(&1, 2)})
-    compile_group = Enum.group_by(c_warnings, &elem(&1, 0), &{elem(&1, 1), elem(&1, 2)})
+    runtime_group = Enum.group_by(r_warnings, & &1.file, &{&1.position, &1.message})
+    compile_group = Enum.group_by(c_warnings, & &1.file, &{&1.position, &1.message})
 
     for source(
           source: source_path,
@@ -727,10 +733,10 @@ defmodule Mix.Compilers.Elixir do
     end
   end
 
-  defp diagnostic({file, location, message}, severity) do
+  defp diagnostic(%{file: file, position: position, message: message, severity: severity}) do
     %Mix.Task.Compiler.Diagnostic{
       file: file,
-      position: location,
+      position: position,
       message: message,
       severity: severity,
       compiler_name: "Elixir"