1 files changed, 44 insertions, 0 deletions
diff --git a/warning.rb b/warning.rb
new file mode 100644
index 0000000000..8361176491
--- /dev/null
+++ b/warning.rb
@@ -0,0 +1,44 @@
+# encoding: utf-8
+# fronzen-string-literal: true
+
+module Kernel
+
+  # call-seq:
+  #    warn(*msgs, uplevel: nil)   -> nil
+  #
+  # If warnings have been disabled (for example with the
+  # <code>-W0</code> flag), does nothing.  Otherwise,
+  # converts each of the messages to strings, appends a newline
+  # character to the string if the string does not end in a newline,
+  # and calls Warning.warn with the string.
+  #
+  #    warn("warning 1", "warning 2")
+  #
+  #  <em>produces:</em>
+  #
+  #    warning 1
+  #    warning 2
+  #
+  # If the <code>uplevel</code> keyword argument is given, the string will
+  # be prepended with information for the given caller frame in
+  # the same format used by the <code>rb_warn</code> C function.
+  #
+  #    # In baz.rb
+  #    def foo
+  #      warn("invalid call to foo", uplevel: 1)
+  #    end
+  #
+  #    def bar
+  #      foo
+  #    end
+  #
+  #    bar
+  #
+  #  <em>produces:</em>
+  #
+  #    baz.rb:6: warning: invalid call to foo
+  #
+  def warn(*msgs, uplevel: nil)
+    __builtin_rb_warn_m(msgs, uplevel)
+  end
+end