Default to universal times throughout File

Author: José Valim

CHANGELOG.md

@@ -140,7 +140,7 @@ and is using Erlang 17.1, remember to update to at least Erlang 17.3.
   * [Code] `:delegate_locals_to` failed to delegate to the chosen module in many situations and messed up stacktraces. This option has therefore been replaced by imports
   * [Code] Store the documentation line in the metadata returned by `Code.get_docs/2`
   * [Exception] Do not fail when calculating an exception message, even if the message is invalid
-  * [File] Ensure `File.touch/2` and `File.touch!/2` work with universal time
+  * [File] Ensure `File.touch/2` and `File.stat/2` receive and return universal times. Previously they would work with local times which are not monotonically increasing, which could present issues on scripts. If the times are being shown to the user, `time: :local` can be given as argument
   * [Float] Support complete scientific notation in `Float.parse/1`
   * [Kernel] Do not expand `in/2` argument in module body
   * [Kernel] Throw syntax error for undefind atom/alias syntax `:foo.Bar`

lib/elixir/lib/file.ex

@@ -260,13 +260,14 @@ defmodule File do
 
   The values for `:time` can be:
 
+    * `:universal` - returns a `{date, time}` tuple in UTC (default)
     * `:local` - returns a `{date, time}` tuple using the machine time
-    * `:universal` - returns a `{date, time}` tuple in UTC
     * `:posix` - returns the time as integer seconds since epoch
 
   """
   @spec stat(Path.t, stat_options) :: {:ok, File.Stat.t} | {:error, posix}
   def stat(path, opts \\ []) do
+    opts = Keyword.put_new(opts, :time, :universal)
     case F.read_file_info(IO.chardata_to_string(path), opts) do
       {:ok, fileinfo} ->
         {:ok, File.Stat.from_record(fileinfo)}
@@ -304,13 +305,14 @@ defmodule File do
 
   The values for `:time` can be:
 
+    * `:universal` - returns a `{date, time}` tuple in UTC (default)
     * `:local` - returns a `{date, time}` tuple using the machine time
-    * `:universal` - returns a `{date, time}` tuple in UTC
     * `:posix` - returns the time as integer seconds since epoch
 
   """
   @spec lstat(Path.t, stat_options) :: {:ok, File.Stat.t} | {:error, posix}
   def lstat(path, opts \\ []) do
+    opts = Keyword.put_new(opts, :time, :universal)
     case F.read_link_info(IO.chardata_to_string(path), opts) do
       {:ok, fileinfo} ->
         {:ok, File.Stat.from_record(fileinfo)}
@@ -339,6 +341,7 @@ defmodule File do
   """
   @spec write_stat(Path.t, File.Stat.t, stat_options) :: :ok | {:error, posix}
   def write_stat(path, stat, opts \\ []) do
+    opts = Keyword.put_new(opts, :time, :universal)
     F.write_file_info(IO.chardata_to_string(path), File.Stat.to_record(stat), opts)
   end
 

lib/elixir/test/elixir/file_test.exs

@@ -1527,7 +1527,7 @@ defmodule FileTest do
       refute File.exists?(fixture)
       assert File.touch(fixture, time) == :ok
       assert {:ok, ""} == File.read(fixture)
-      assert File.stat!(fixture, time: :universal).mtime == time
+      assert File.stat!(fixture).mtime == time
     after
       File.rm(fixture)
     end

lib/mix/lib/mix/utils.ex

@@ -101,7 +101,7 @@ defmodule Mix.Utils do
   def last_modified(path) do
     now = :calendar.universal_time
 
-    case File.stat(path, time: :universal) do
+    case File.stat(path) do
       {:ok, %File.Stat{mtime: mtime}} when mtime > now ->
         Mix.shell.error("warning: mtime (modified time) for \"#{path}\" was set to the future, resetting to now")
         File.touch!(path, now)