[GR-18163] Update IO.readlines to ignore negative limit parameters

PullRequest: truffleruby/3228

Author: bjfish

CHANGELOG.md

@@ -45,6 +45,7 @@ Compatibility:
 * Update `String#lstrip!` to remove leading null characters (#2607, @bjfish).
 * Update `File.utime` to return the number of file names in the arguments (#2616, @bjfish).
 * Update `Dir.foreach` to accept an `encoding` parameter (#2627, @bjfish).
+* Update `IO.readlines` to ignore negative limit parameters (#2625 , @bjfish).
 
 Performance:
 

spec/ruby/core/io/shared/readlines.rb

@@ -73,6 +73,11 @@
         result = IO.send(@method, @name, 10, &@object)
         (result ? result : ScratchPad.recorded).should == IOSpecs.lines_limit
       end
+
+      it "ignores the object as a limit if it is negative" do
+        result = IO.send(@method, @name, -2, &@object)
+        (result ? result : ScratchPad.recorded).should == IOSpecs.lines
+      end
     end
 
     describe "when the object is a String" do

src/main/ruby/truffleruby/core/io.rb

@@ -464,6 +464,7 @@ def self.foreach(name, separator=undefined, limit=undefined, options=undefined,
         options = Truffle::Type.coerce_to value, Hash, :to_hash
       end
     end
+    limit = nil if limit && limit < 0
 
     options = {} if Primitive.undefined?(options)
     case options