Disallow the unless...else code pattern.

Author: nirvdrum

.rubocop.yml

@@ -369,3 +369,8 @@ Style/StringLiterals:
   - single_quotes
   - double_quotes
   ConsistentQuotesInMultiline: false
+
+# Supports --auto-correct
+Style/UnlessElse:
+  Description: Checks for unless expressions with else clauses.
+  Enabled: true

src/main/ruby/core/hash.rb

@@ -245,12 +245,7 @@ def keep_if
   def merge(*others)
     current = self.dup
 
-    unless block_given?
-      others.each do |other|
-        other = Truffle::Type.coerce_to(other, Hash, :to_hash)
-        current = Truffle::HashOperations.hash_merge(current, other)
-      end
-    else
+    if block_given?
       others.each do |other|
         other.each do |k, v|
           other = Truffle::Type.coerce_to(other, Hash, :to_hash)
@@ -261,6 +256,11 @@ def merge(*others)
           end
         end
       end
+    else
+      others.each do |other|
+        other = Truffle::Type.coerce_to(other, Hash, :to_hash)
+        current = Truffle::HashOperations.hash_merge(current, other)
+      end
     end
     current
   end

src/main/ruby/core/kernel.rb

@@ -231,14 +231,14 @@ def eval(str, a_binding=nil, file=nil, line=nil)
     str = str.to_str unless str.class == String
     file = file.to_str unless file.class == String
     line = line.to_i unless line.is_a?(Integer)
-    unless a_binding
-      receiver = self
-      a_binding = Truffle.invoke_primitive(:caller_binding)
-    else
+    if a_binding
       unless a_binding.class == Binding
         raise TypeError, "Wrong argument type #{a_binding.class} (expected binding)"
       end
       receiver = a_binding.receiver
+    else
+      receiver = self
+      a_binding = Truffle.invoke_primitive(:caller_binding)
     end
 
     Truffle.invoke_primitive(:kernel_eval, receiver, str, a_binding, file, line)

src/main/ruby/core/regexp.rb

@@ -166,10 +166,10 @@ def self.union(*patterns)
     str = ''.encode(enc)
 
     patterns = patterns.map do |pat|
-      unless pat.kind_of? Regexp
-        StringValue(pat)
-      else
+      if pat.kind_of? Regexp
         pat
+      else
+        StringValue(pat)
       end
     end