One-line pattern matching is no longer experimental

https://github.com/ruby/dev-meeting-log/blob/master/DevelopersMeeting20210715Japan.md#feature-17724-make-the-pin-operator-support-instanceclassglobal-variables-jeremyevans0

NEWS.md

@@ -23,6 +23,8 @@ Note that each entry is kept to a minimum, see links for details.
     #=> [3, 5]
     ```
 
+* One-line pattern matching is no longer experimental.
+
 * Multiple assignment evaluation order has been made consistent with
   single assignment evaluation order.  With single assignment, Ruby
   uses a left-to-right evaluation order.  With this code:

doc/syntax/pattern_matching.rdoc

@@ -441,7 +441,7 @@ Additionally, when matching custom classes, the expected class can be specified
 
 == Current feature status
 
-As of Ruby 3.0, one-line pattern matching and find patterns are considered _experimental_: its syntax can change in the future. Every time you use these features in code, a warning will be printed:
+As of Ruby 3.1, find patterns are considered _experimental_: its syntax can change in the future. Every time you use these features in code, a warning will be printed:
 
   [0] => [*, 0, *]
   # warning: Find pattern is experimental, and the behavior may change in future versions of Ruby!

parse.y

@@ -523,7 +523,6 @@ static NODE *new_find_pattern(struct parser_params *p, NODE *constant, NODE *fnd
 static NODE *new_find_pattern_tail(struct parser_params *p, ID pre_rest_arg, NODE *args, ID post_rest_arg, const YYLTYPE *loc);
 static NODE *new_hash_pattern(struct parser_params *p, NODE *constant, NODE *hshptn, const YYLTYPE *loc);
 static NODE *new_hash_pattern_tail(struct parser_params *p, NODE *kw_args, ID kw_rest_arg, const YYLTYPE *loc);
-static void warn_one_line_pattern_matching(struct parser_params *p, NODE *node, NODE *pattern, bool right_assign);
 
 static NODE *new_kw_arg(struct parser_params *p, NODE *k, const YYLTYPE *loc);
 static NODE *args_with_numbered(struct parser_params*,NODE*,int);
@@ -1739,7 +1738,6 @@ expr		: command_call
 			p->ctxt.in_kwarg = $<ctxt>3.in_kwarg;
 		    /*%%%*/
 			$$ = NEW_CASE3($1, NEW_IN($5, 0, 0, &@5), &@$);
-			warn_one_line_pattern_matching(p, $$, $5, true);
 		    /*% %*/
 		    /*% ripper: case!($1, in!($5, Qnil, Qnil)) %*/
 		    }
@@ -1758,7 +1756,6 @@ expr		: command_call
 			p->ctxt.in_kwarg = $<ctxt>3.in_kwarg;
 		    /*%%%*/
 			$$ = NEW_CASE3($1, NEW_IN($5, NEW_TRUE(&@5), NEW_FALSE(&@5), &@5), &@$);
-			warn_one_line_pattern_matching(p, $$, $5, false);
 		    /*% %*/
 		    /*% ripper: case!($1, in!($5, Qnil, Qnil)) %*/
 		    }
@@ -12152,17 +12149,6 @@ new_hash_pattern_tail(struct parser_params *p, NODE *kw_args, ID kw_rest_arg, co
     return node;
 }
 
-static void
-warn_one_line_pattern_matching(struct parser_params *p, NODE *node, NODE *pattern, bool right_assign)
-{
-    enum node_type type;
-    type = nd_type(pattern);
-
-    if (rb_warning_category_enabled_p(RB_WARN_CATEGORY_EXPERIMENTAL) &&
-	!(right_assign && (type == NODE_LASGN || type == NODE_DASGN || type == NODE_DASGN_CURR)))
-	rb_warn0L_experimental(nd_line(node), "One-line pattern matching is experimental, and the behavior may change in future versions of Ruby!");
-}
-
 static NODE*
 dsym_node(struct parser_params *p, NODE *node, const YYLTYPE *loc)
 {

test/ruby/test_pattern_matching.rb

@@ -1545,8 +1545,6 @@ END
 
   def test_experimental_warning
     assert_experimental_warning("case [0]; in [*, 0, *]; end")
-    assert_experimental_warning("0 => 0")
-    assert_experimental_warning("0 in a")
   end
 end
 END_of_GUARD