Track source for warnings, closes #14093

Author: josevalim

lib/elixir/lib/module/parallel_checker.ex

@@ -239,7 +239,7 @@ defmodule Module.ParallelChecker do
       |> Module.Types.warnings(file, definitions, no_warn_undefined, cache)
       |> Kernel.++(behaviour_warnings)
       |> group_warnings()
-      |> emit_warnings(log?)
+      |> emit_warnings(file, log?)
 
     Enum.each(after_verify, fn {verify_mod, verify_fun} ->
       apply(verify_mod, verify_fun, [module])
@@ -320,9 +320,9 @@ defmodule Module.ParallelChecker do
     Enum.sort(ungrouped ++ grouped)
   end
 
-  defp emit_warnings(warnings, log?) do
+  defp emit_warnings(warnings, file, log?) do
     Enum.flat_map(warnings, fn {locations, diagnostic} ->
-      diagnostics = Enum.map(locations, &to_diagnostic(diagnostic, &1))
+      diagnostics = Enum.map(locations, &to_diagnostic(diagnostic, file, &1))
       log? and print_diagnostics(diagnostics)
       diagnostics
     end)
@@ -336,10 +336,12 @@ defmodule Module.ParallelChecker do
     :elixir_errors.print_diagnostics(diagnostics)
   end
 
-  defp to_diagnostic(diagnostic, {file, position, mfa}) when is_list(position) do
+  defp to_diagnostic(diagnostic, source, {file, position, mfa}) when is_list(position) do
+    file = Path.absname(file)
+
     %{
       severity: :warning,
-      source: file,
+      source: source,
       file: file,
       position: position_to_tuple(position),
       stacktrace: [to_stacktrace(file, position, mfa)],

lib/elixir/src/elixir_errors.erl

@@ -92,7 +92,10 @@ emit_diagnostic(Severity, Position, File, Message, Stacktrace, Options) ->
 
   Diagnostic = #{
     severity => Severity,
-    source => File,
+    source => case get(elixir_compiler_file) of
+      undefined -> File;
+      CompilerFile -> CompilerFile
+    end,
     file => File,
     position => Position,
     message => unicode:characters_to_binary(Message),

lib/elixir/test/elixir/module/types/integration_test.exs

@@ -36,7 +36,7 @@ defmodule Module.Types.IntegrationTest do
         """
       }
 
-      modules = compile(files)
+      modules = compile_modules(files)
 
       assert [
                {{:c, 0}, %{}},
@@ -243,6 +243,37 @@ defmodule Module.Types.IntegrationTest do
 
       assert_no_warnings(files)
     end
+
+    test "returns diagnostics with source and file" do
+      files = %{
+        "a.ex" => """
+        defmodule A do
+          @file "generated.ex"
+          def fun(arg) do
+            :ok = List.to_tuple(arg)
+          end
+        end
+        """
+      }
+
+      {_modules, warnings} = with_compile_warnings(files)
+
+      assert [
+               %{
+                 message: "the following pattern will never match" <> _,
+                 file: file,
+                 source: source
+               }
+             ] = warnings.runtime_warnings
+
+      assert String.ends_with?(source, "a.ex")
+      assert Path.type(source) == :absolute
+      assert String.ends_with?(file, "generated.ex")
+      assert Path.type(file) == :absolute
+    after
+      :code.delete(A)
+      :code.purge(A)
+    end
   end
 
   describe "undefined warnings" do
@@ -980,27 +1011,39 @@ defmodule Module.Types.IntegrationTest do
   defp capture_compile_warnings(files) do
     in_tmp(fn ->
       paths = generate_files(files)
-      capture_io(:stderr, fn -> compile_files(paths) end)
+      capture_io(:stderr, fn -> compile_to_path(paths) end)
+    end)
+  end
+
+  defp with_compile_warnings(files) do
+    in_tmp(fn ->
+      paths = generate_files(files)
+      with_io(:stderr, fn -> compile_to_path(paths) end) |> elem(0)
     end)
   end
 
-  defp compile(files) do
+  defp compile_modules(files) do
     in_tmp(fn ->
       paths = generate_files(files)
-      compile_files(paths)
+      {modules, _warnings} = compile_to_path(paths)
+
+      Map.new(modules, fn module ->
+        {^module, binary, _filename} = :code.get_object_code(module)
+        {module, binary}
+      end)
     end)
   end
 
-  defp compile_files(paths) do
-    {:ok, modules, _warnings} =
+  defp compile_to_path(paths) do
+    {:ok, modules, warnings} =
       Kernel.ParallelCompiler.compile_to_path(paths, ".", return_diagnostics: true)
 
-    Map.new(modules, fn module ->
-      {^module, binary, _filename} = :code.get_object_code(module)
+    for module <- modules do
       :code.delete(module)
       :code.purge(module)
-      {module, binary}
-    end)
+    end
+
+    {modules, warnings}
   end
 
   defp generate_files(files) do

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -1045,12 +1045,15 @@ defmodule Mix.Tasks.Compile.ElixirTest do
 
       # Compiles with missing external resources
       file = Path.absname("lib/a.eex")
+      source = Path.absname("lib/a.ex")
 
       assert capture_io(:stderr, fn ->
-               assert {:ok, [%Mix.Task.Compiler.Diagnostic{file: ^file, position: 13}]} =
+               assert {:ok,
+                       [%Mix.Task.Compiler.Diagnostic{source: ^source, file: ^file, position: 13}]} =
                         Mix.Tasks.Compile.Elixir.run([])
 
-               assert {:noop, [%Mix.Task.Compiler.Diagnostic{file: ^file, position: 13}]} =
+               assert {:noop,
+                       [%Mix.Task.Compiler.Diagnostic{source: ^source, file: ^file, position: 13}]} =
                         Mix.Tasks.Compile.Elixir.run(["--all-warnings"])
              end) =~ "oops"