Fix Regexp.new - warn when 3d argument has unsupported value

Author: andrykonchin

CHANGELOG.md

@@ -22,6 +22,7 @@ Compatibility:
 * Range literals of integers are now created at parse time like in CRuby (#2622, @aardvark179).
 * Fix `IO.pipe` - allow overriding `IO.new` that is used to create new pipes (#2692, @andykonchin).
 * Fix exception message when there are missing or extra keyword arguments - it contains all the missing/extra keywords now (#1522, @andrykonchin).
+* Fix `Regexp.new` to coerce non-String arguments (#2705, @andrykonchin).
 
 Performance:
 

spec/tags/core/regexp/compile_tags.txt

@@ -1,4 +1 @@
-fails:Regexp.compile given a String ignores the third argument if it is 'e' or 'euc' (case-insensitive)
-fails:Regexp.compile given a String ignores the third argument if it is 's' or 'sjis' (case-insensitive)
-fails:Regexp.compile given a String ignores the third argument if it is 'u' or 'utf8' (case-insensitive)
 fails(immutable regexp):Regexp.compile works by default for subclasses with overridden #initialize

spec/tags/core/regexp/new_tags.txt

@@ -1,4 +1 @@
-fails:Regexp.new given a String ignores the third argument if it is 'e' or 'euc' (case-insensitive)
-fails:Regexp.new given a String ignores the third argument if it is 's' or 'sjis' (case-insensitive)
-fails:Regexp.new given a String ignores the third argument if it is 'u' or 'utf8' (case-insensitive)
 fails(immutable regexp):Regexp.new works by default for subclasses with overridden #initialize

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

@@ -130,12 +130,11 @@ def self.union(*patterns)
   end
   Truffle::Graal.always_split(method(:union))
 
-  def self.new(pattern, opts=undefined, lang=nil)
+  def self.new(pattern, opts=undefined, encoding=nil)
     if Primitive.object_kind_of?(pattern, Regexp)
       warn 'flags ignored' unless Primitive.undefined?(opts)
       opts = pattern.options
       pattern = pattern.source
-    elsif Primitive.object_kind_of?(pattern, String)
     else
       pattern = Truffle::Type.rb_convert_type pattern, String, :to_str
     end
@@ -148,8 +147,15 @@ def self.new(pattern, opts=undefined, lang=nil)
       opts = 0
     end
 
-    code = lang[0] if lang
-    opts |= NOENCODING if code == ?n or code == ?N
+    if encoding
+      encoding = Truffle::Type.rb_convert_type encoding, String, :to_str
+      code = encoding[0]
+      if code == ?n or code == ?N
+        opts |= NOENCODING
+      else
+        warn "encoding option is ignored - #{encoding}"
+      end
+    end
 
     Primitive.regexp_compile pattern, opts # may be overridden by subclasses
   end