Deprecate Kernel#open and IO support for subprocess creation/forking

Deprecate Kernel#open and IO support for subprocess creation and
forking. This deprecates subprocess creation and forking in

- Kernel#open
- URI.open
- IO.binread
- IO.foreach
- IO.readlines
- IO.read
- IO.write

This behavior is slated to be removed in Ruby 4.0

[Feature #19630]

1 files changed, 19 insertions, 2 deletions

diff --git a/spec/ruby/core/io/readlines_spec.rb b/spec/ruby/core/io/readlines_spec.rb
index d6c4d539cf..3a6ff3d0f3 100644
--- a/spec/ruby/core/io/readlines_spec.rb
+++ b/spec/ruby/core/io/readlines_spec.rb
@@ -180,13 +180,20 @@ describe "IO.readlines" do
       platform_is :windows do
         cmd = "|cmd.exe /C echo hello&echo line2"
       end
-      lines = IO.readlines(cmd)
+
+      lines = nil
+      suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+        lines = IO.readlines(cmd)
+      end
       lines.should == ["hello\n", "line2\n"]
     end
 
     platform_is_not :windows do
       it "gets data from a fork when passed -" do
-        lines = IO.readlines("|-")
+        lines = nil
+        suppress_warning do # https://bugs.ruby-lang.org/issues/19630
+          lines = IO.readlines("|-")
+        end
 
         if lines # parent
           lines.should == ["hello\n", "from a fork\n"]
@@ -199,6 +206,16 @@ describe "IO.readlines" do
     end
   end
 
+  ruby_version_is "3.3" do
+    # https://bugs.ruby-lang.org/issues/19630
+    it "warns about deprecation given a path with a pipe" do
+      cmd = "|echo ok"
+      -> {
+        IO.readlines(cmd)
+      }.should complain(/IO process creation with a leading '\|'/)
+    end
+  end
+
   it_behaves_like :io_readlines, :readlines
   it_behaves_like :io_readlines_options_19, :readlines
 end