No writing to numbered parameters

Fixes [Bug #21117]

Author: kddnewton

lib/prism/parse_result/newlines.rb

@@ -63,7 +63,7 @@ def visit_statements_node(node)
 
   class Node
     def newline_flag? # :nodoc:
-      @newline_flag ? true : false
+      defined?(@newline_flag)
     end
 
     def newline_flag!(lines) # :nodoc:

src/prism.c

@@ -21223,6 +21223,7 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    pm_refute_numbered_parameter(parser, node->location.start, node->location.end);
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 
@@ -21341,6 +21342,7 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    pm_refute_numbered_parameter(parser, node->location.start, node->location.end);
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 
@@ -21469,6 +21471,7 @@ parse_expression_infix(pm_parser_t *parser, pm_node_t *node, pm_binding_power_t
                     return result;
                 }
                 case PM_LOCAL_VARIABLE_READ_NODE: {
+                    pm_refute_numbered_parameter(parser, node->location.start, node->location.end);
                     pm_local_variable_read_node_t *cast = (pm_local_variable_read_node_t *) node;
                     parser_lex(parser);
 

test/prism/errors/numbered_and_write.txt

@@ -0,0 +1,3 @@
+tap { _1 &&= 1 }
+      ^~ _1 is reserved for numbered parameters
+

test/prism/errors/numbered_operator_write.txt

@@ -0,0 +1,3 @@
+tap { _1 += 1 }
+      ^~ _1 is reserved for numbered parameters
+

test/prism/errors/numbered_or_write.txt

@@ -0,0 +1,3 @@
+tap { _1 ||= 1 }
+      ^~ _1 is reserved for numbered parameters
+

test/prism/errors_test.rb

@@ -14,7 +14,10 @@ class ErrorsTest < TestCase
         "targeting_numbered_parameter.txt",
         "defining_numbered_parameter.txt",
         "defining_numbered_parameter_2.txt",
-        "numbered_parameters_in_block_arguments.txt"
+        "numbered_parameters_in_block_arguments.txt",
+        "numbered_and_write.txt",
+        "numbered_or_write.txt",
+        "numbered_operator_write.txt"
       ]
     end