5 files changed, 10 insertions, 3 deletions
diff --git a/compile.c b/compile.c
index 1b23d2133b..3139e9807f 100644
--- a/compile.c
+++ b/compile.c
@@ -2011,6 +2011,9 @@ rb_iseq_cdhash_cmp(VALUE val, VALUE lit)
         const struct RComplex *comp2 = RCOMPLEX(lit);
         return rb_iseq_cdhash_cmp(comp1->real, comp2->real) || rb_iseq_cdhash_cmp(comp1->imag, comp2->imag);
     }
+    else if (tlit == T_REGEXP) {
+        return rb_reg_equal(val, lit) ? 0 : -1;
+    }
     else {
         UNREACHABLE_RETURN(-1);
     }
@@ -2033,6 +2036,8 @@ rb_iseq_cdhash_hash(VALUE a)
         return rb_rational_hash(a);
       case T_COMPLEX:
         return rb_complex_hash(a);
+      case T_REGEXP:
+        return NUM2LONG(rb_reg_hash(a));
       default:
         UNREACHABLE_RETURN(0);
     }
diff --git a/internal/re.h b/internal/re.h
index 28fa3fb51c..a19ad934f7 100644
--- a/internal/re.h
+++ b/internal/re.h
@@ -18,6 +18,8 @@ VALUE rb_reg_check_preprocess(VALUE);
 long rb_reg_search0(VALUE, VALUE, long, int, int);
 VALUE rb_reg_match_p(VALUE re, VALUE str, long pos);
 bool rb_reg_start_with_p(VALUE re, VALUE str);
+VALUE rb_reg_hash(VALUE re);
+VALUE rb_reg_equal(VALUE re1, VALUE re2);
 void rb_backref_set_string(VALUE string, long pos, long len);
 void rb_match_unbusy(VALUE);
 int rb_match_count(VALUE match);
diff --git a/parse.y b/parse.y
index 0b69bc1d7e..e333730935 100644
--- a/parse.y
+++ b/parse.y
@@ -12189,7 +12189,6 @@ hash_literal_key_p(VALUE k)
 {
     switch (OBJ_BUILTIN_TYPE(k)) {
       case T_NODE:
-      case T_REGEXP:
 	return false;
       default:
 	return true;
diff --git a/re.c b/re.c
index 5809d26bf3..64078aefd2 100644
--- a/re.c
+++ b/re.c
@@ -3009,7 +3009,7 @@ static st_index_t reg_hash(VALUE re);
  * See also Object#hash.
  */
 
-static VALUE
+VALUE
 rb_reg_hash(VALUE re)
 {
     st_index_t hashval = reg_hash(re);
@@ -3043,7 +3043,7 @@ reg_hash(VALUE re)
  *     /abc/u == /abc/n   #=> false
  */
 
-static VALUE
+VALUE
 rb_reg_equal(VALUE re1, VALUE re2)
 {
     if (re1 == re2) return Qtrue;
diff --git a/test/ruby/test_literal.rb b/test/ruby/test_literal.rb
index ed93b74cff..579a39dee8 100644
--- a/test/ruby/test_literal.rb
+++ b/test/ruby/test_literal.rb
@@ -484,6 +484,7 @@ class TestRubyLiteral < Test::Unit::TestCase
       '1.0r',
       '1.0i',
       '1.72723e-77',
+      '//',
     ) do |key|
       assert_warning(/key #{Regexp.quote(eval(key).inspect)} is duplicated/) do
         eval("{#{key} => :bar, #{key} => :foo}")