irb.rb: restore the last error

* lib/irb.rb (eval_input): restore the last error `$!`, as the
  previous result.  [Feature #14684]

* lib/irb/context.rb (evaluate): add `exception` keyword argument
  to set the last error.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63150 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/irb/context.rb b/lib/irb/context.rb
index 1a06ebfad1..b82aaea6a6 100644
--- a/lib/irb/context.rb
+++ b/lib/irb/context.rb
@@ -376,8 +376,12 @@ module IRB
       @debug_level > 0
     end
 
-    def evaluate(line, line_no) # :nodoc:
+    def evaluate(line, line_no, exception: nil) # :nodoc:
       @line_no = line_no
+      if exception
+        line = "begin ::Kernel.raise _; rescue _.class; #{line}; end"
+        @workspace.local_variable_set(:_, exception)
+      end
       set_last_value(@workspace.evaluate(self, line, irb_path, line_no))
     end