From a459269fa89137ab232928cfeedfd3edeca3d74b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?George=20Guimar=C3=A3es?= <george.guimaraes@gmail.com>
Date: Fri, 27 Feb 2026 11:21:43 -0300
Subject: [PATCH 1/2] Print formatted file names in mix format --verbose, add
 --verbose flag

---
 lib/mix/lib/mix/tasks/format.ex        | 32 ++++++++++++++++++++------
 lib/mix/test/mix/tasks/format_test.exs | 29 +++++++++++++++++++++++
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/lib/mix/lib/mix/tasks/format.ex b/lib/mix/lib/mix/tasks/format.ex
index 9f84edc7c71..ef22c2c4501 100644
--- a/lib/mix/lib/mix/tasks/format.ex
+++ b/lib/mix/lib/mix/tasks/format.ex
@@ -77,6 +77,8 @@ defmodule Mix.Tasks.Format do
 
     * `--dry-run` - does not save files after formatting.
 
+    * `--verbose` - prints the names of files that were formatted.
+
     * `--dot-formatter` - path to the file with formatter configuration.
       Defaults to `.formatter.exs` if one is available. See the
       "Formatting options" section above for more information.
@@ -199,6 +201,7 @@ defmodule Mix.Tasks.Format do
     no_exit: :boolean,
     dot_formatter: :string,
     dry_run: :boolean,
+    verbose: :boolean,
     stdin_filename: :string,
     force: :boolean,
     migrate: :boolean
@@ -764,18 +767,27 @@ defmodule Mix.Tasks.Format do
         :ok
 
       true ->
-        write_or_print(file, input, output)
+        write_or_print(file, input, output, task_opts)
     end
   rescue
     exception ->
       {:exit, file, exception, __STACKTRACE__}
   end
 
-  defp write_or_print(file, input, output) do
+  defp write_or_print(file, input, output, task_opts) do
     cond do
-      file == :stdin -> IO.write(output)
-      input == output -> :ok
-      true -> File.write!(file, output)
+      file == :stdin ->
+        IO.write(output)
+
+      input == output ->
+        :ok
+
+      true ->
+        File.write!(file, output)
+
+        if task_opts[:verbose] do
+          Mix.shell().info([:green, "* formatting ", :reset, Path.relative_to_cwd(file)])
+        end
     end
 
     :ok
@@ -795,12 +807,18 @@ defmodule Mix.Tasks.Format do
     :ok
   end
 
-  defp check!({[{:exit, :stdin, exception, stacktrace} | _], _not_formatted}, _task_opts) do
+  defp check!(
+         {[{:exit, :stdin, exception, stacktrace} | _], _not_formatted},
+         _task_opts
+       ) do
     Mix.shell().error("mix format failed for stdin")
     reraise exception, stacktrace
   end
 
-  defp check!({[{:exit, file, exception, stacktrace} | _], _not_formatted}, _task_opts) do
+  defp check!(
+         {[{:exit, file, exception, stacktrace} | _], _not_formatted},
+         _task_opts
+       ) do
     Mix.shell().error("mix format failed for file: #{Path.relative_to_cwd(file)}")
     reraise exception, stacktrace
   end
diff --git a/lib/mix/test/mix/tasks/format_test.exs b/lib/mix/test/mix/tasks/format_test.exs
index d5d17bbace4..eaf1aa1aade 100644
--- a/lib/mix/test/mix/tasks/format_test.exs
+++ b/lib/mix/test/mix/tasks/format_test.exs
@@ -85,6 +85,35 @@ defmodule Mix.Tasks.FormatTest do
     end)
   end
 
+  test "prints formatted file names with --verbose", context do
+    in_tmp(context.test, fn ->
+      File.write!("a.ex", """
+      foo bar
+      """)
+
+      File.write!("b.ex", """
+      foo(bar)
+      """)
+
+      Mix.Tasks.Format.run(["a.ex", "b.ex", "--verbose"])
+
+      assert_received {:mix_shell, :info, ["* formatting a.ex"]}
+      refute_received {:mix_shell, :info, ["* formatting b.ex"]}
+    end)
+  end
+
+  test "does not print formatted file names by default", context do
+    in_tmp(context.test, fn ->
+      File.write!("a.ex", """
+      foo bar
+      """)
+
+      Mix.Tasks.Format.run(["a.ex"])
+
+      refute_received {:mix_shell, :info, ["* formatting a.ex"]}
+    end)
+  end
+
   test "does not try to format a directory that matches a given pattern", context do
     in_tmp(context.test, fn ->
       File.mkdir_p!("a.ex")

From 07e4d73b3c5e4448624437c57703e6883c156634 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Valim?= <jose.valim@gmail.com>
Date: Sat, 28 Feb 2026 11:43:06 +0100
Subject: [PATCH 2/2] Apply suggestions from code review

---
 lib/mix/lib/mix/tasks/format.ex | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/lib/mix/lib/mix/tasks/format.ex b/lib/mix/lib/mix/tasks/format.ex
index ef22c2c4501..de5f0dd85ef 100644
--- a/lib/mix/lib/mix/tasks/format.ex
+++ b/lib/mix/lib/mix/tasks/format.ex
@@ -807,18 +807,12 @@ defmodule Mix.Tasks.Format do
     :ok
   end
 
-  defp check!(
-         {[{:exit, :stdin, exception, stacktrace} | _], _not_formatted},
-         _task_opts
-       ) do
+  defp check!({[{:exit, :stdin, exception, stacktrace} | _], _not_formatted}, _task_opts) do
     Mix.shell().error("mix format failed for stdin")
     reraise exception, stacktrace
   end
 
-  defp check!(
-         {[{:exit, file, exception, stacktrace} | _], _not_formatted},
-         _task_opts
-       ) do
+  defp check!({[{:exit, file, exception, stacktrace} | _], _not_formatted}, _task_opts) do
     Mix.shell().error("mix format failed for file: #{Path.relative_to_cwd(file)}")
     reraise exception, stacktrace
   end