[ruby/irb] Support --noscript option to not use first non-option argument as script

Also add --script option to turn the option back on.

Previously there wasn't a way to get an interactive IRB session
and access arguments provided on the command line.

Additionally, handle `-` as script as stdin. In Unix-like tools, `-`
means to take standard input instead of a file.  This doesn't
result in exactly the same output for:

```
echo 'p ARGV' > args.rb; irb args.rb a b c
```

and

```
echo 'p ARGV' | irb - a b c
```

Due to how irb handles whether stdin is a tty.

However, this change allows use of `-` as a argument, instead of
giving an unrecognized switch error. This required some small
changes to context.rb (to handle `-` as standard input) and
input-method.rb (to have FileInputMethod accept IO arguments in
addition to strings).

Implements [Feature #15371]

https://github.com/ruby/irb/commit/4192683ba2

1 files changed, 12 insertions, 4 deletions

diff --git a/lib/irb/init.rb b/lib/irb/init.rb
index d2baee2017..d9c4353f39 100644
--- a/lib/irb/init.rb
+++ b/lib/irb/init.rb
@@ -289,6 +289,10 @@ module IRB # :nodoc:
         @CONF[:PROMPT_MODE] = prompt_mode
       when "--noprompt"
         @CONF[:PROMPT_MODE] = :NULL
+      when "--script"
+        noscript = false
+      when "--noscript"
+        noscript = true
       when "--inf-ruby-mode"
         @CONF[:PROMPT_MODE] = :INF_RUBY
       when "--sample-book-mode", "--simple-prompt"
@@ -309,16 +313,20 @@ module IRB # :nodoc:
         IRB.print_usage
         exit 0
       when "--"
-        if opt = argv.shift
+        if !noscript && (opt = argv.shift)
           @CONF[:SCRIPT] = opt
           $0 = opt
         end
         break
-      when /^-/
+      when /^-./
         fail UnrecognizedSwitch, opt
       else
-        @CONF[:SCRIPT] = opt
-        $0 = opt
+        if noscript
+          argv.unshift(opt)
+        else
+          @CONF[:SCRIPT] = opt
+          $0 = opt
+        end
         break
       end
     end