[GR-18163] Update String#split to raise TypeError when false is given

PullRequest: truffleruby/3213

Author: eregon

CHANGELOG.md

@@ -36,6 +36,7 @@ Compatibility:
 * Rewrote `ArrayEachIteratorNode` and re-introduced `each` specs for MRI parity when mutating arrays whilst iterating, rather than crashing (#2587, @MattAlp)
 * Update `String#rindex` to only accept `Regexp` or objects convertable to `String` as the first parameter (#2608, @bjfish).
 * Update `String#<<` to require one argument (#2609, @bjfish).
+* Update `String#split` to raise `TypeError` when false is given (#2606, @bjfish).
 
 Performance:
 

spec/ruby/core/string/split_spec.rb

@@ -589,4 +589,11 @@
       end
     end
   end
+
+  it "raises a TypeError when not called with nil, String, or Regexp" do
+    -> { "hello".split(42) }.should raise_error(TypeError)
+    -> { "hello".split(:ll) }.should raise_error(TypeError)
+    -> { "hello".split(false) }.should raise_error(TypeError)
+    -> { "hello".split(Object.new) }.should raise_error(TypeError)
+  end
 end

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

@@ -61,7 +61,9 @@ def split(string, pattern, limit, &orig_block)
           return orig_block ? dup_string : result
         end
 
-        pattern ||= ($; || DEFAULT_PATTERN)
+        if Primitive.nil?(pattern)
+          pattern = ($; || DEFAULT_PATTERN)
+        end
 
         if pattern == DEFAULT_PATTERN
           awk_limit = limit < 0 ? -1 : limit