Avoid usage of the magic number `(NODE*)-1`

This magic number has two meanings depending upon the context:

* "required keyword argument (no name)" on NODE_LASGN (`def foo(x:)`)
* "rest argument (no name)" on NODE_MASGN and NODE_POSTARG
  ('a, b, * = ary` or `a, b, *, z = ary`)

To show this intention explicitly, two macros are introduced:
NODE_SPECIAL_REQUIRED_KEYWORD and NODE_SPECIAL_NO_NAME_REST.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60650 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

4 files changed, 23 insertions, 20 deletions

diff --git a/compile.c b/compile.c
index 4bcbd0cec8..76bc107abe 100644
--- a/compile.c
+++ b/compile.c
@@ -3708,7 +3708,7 @@ compile_massign(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node,
     const NODE *rhsn = node->nd_value;
     const NODE *splatn = node->nd_args;
     const NODE *lhsn = node->nd_head;
-    int lhs_splat = (splatn && (VALUE)splatn != (VALUE)-1) ? 1 : 0;
+    int lhs_splat = (splatn && splatn != NODE_SPECIAL_NO_NAME_REST) ? 1 : 0;
 
     if (!popped || splatn || !compile_massign_opt(iseq, ret, rhsn, lhsn)) {
 	int llen = 0;
@@ -3765,12 +3765,12 @@ compile_massign(rb_iseq_t *iseq, LINK_ANCHOR *const ret, const NODE *const node,
 		const NODE *postn = splatn->nd_2nd;
 		const NODE *restn = splatn->nd_1st;
 		int num = (int)postn->nd_alen;
-		int flag = 0x02 | (((VALUE)restn == (VALUE)-1) ? 0x00 : 0x01);
+		int flag = 0x02 | ((restn == NODE_SPECIAL_NO_NAME_REST) ? 0x00 : 0x01);
 
 		ADD_INSN2(ret, nd_line(splatn), expandarray,
 			  INT2FIX(num), INT2FIX(flag));
 
-		if ((VALUE)restn != (VALUE)-1) {
+		if (restn != NODE_SPECIAL_NO_NAME_REST) {
 		    CHECK(compile_massign_lhs(iseq, ret, restn));
 		}
 		while (postn) {
diff --git a/node.c b/node.c
index 71a6d18023..48fdf03c0a 100644
--- a/node.c
+++ b/node.c
@@ -366,12 +366,12 @@ dump_node(VALUE buf, VALUE indent, int comment, NODE *node)
 	ANN("example: a, b = foo");
 	F_NODE(nd_value, "rhsn");
 	F_NODE(nd_head, "lhsn");
-	if ((VALUE)node->nd_args != (VALUE)-1) {
+	if (node->nd_args != NODE_SPECIAL_NO_NAME_REST) {
 	    LAST_NODE;
 	    F_NODE(nd_args, "splatn");
 	}
 	else {
-	    F_MSG(nd_args, "splatn", "-1 (rest argument without name)");
+	    F_MSG(nd_args, "splatn", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
 	}
 	return;
 
@@ -402,8 +402,8 @@ dump_node(VALUE buf, VALUE indent, int comment, NODE *node)
       asgn:
 	F_ID(nd_vid, "variable");
 	LAST_NODE;
-	if (node->nd_value == (NODE *)-1) {
-	    F_MSG(nd_value, "rvalue", "(required keyword argument)");
+	if (node->nd_value == NODE_SPECIAL_REQUIRED_KEYWORD) {
+	    F_MSG(nd_value, "rvalue", "NODE_SPECIAL_REQUIRED_KEYWORD (required keyword argument)");
 	}
 	else {
 	    F_NODE(nd_value, "rvalue");
@@ -983,11 +983,11 @@ dump_node(VALUE buf, VALUE indent, int comment, NODE *node)
 	ANN("post arguments");
 	ANN("format: *[nd_1st], [nd_2nd..] = ..");
 	ANN("example: a, *rest, z = foo");
-	if ((VALUE)node->nd_1st != (VALUE)-1) {
+	if (node->nd_1st != NODE_SPECIAL_NO_NAME_REST) {
 	    F_NODE(nd_1st, "rest argument");
 	}
 	else {
-	    F_MSG(nd_1st, "rest argument", "-1 (rest argument without name)");
+	    F_MSG(nd_1st, "rest argument", "NODE_SPECIAL_NO_NAME_REST (rest argument without name)");
 	}
 	LAST_NODE;
 	F_NODE(nd_2nd, "post arguments");
diff --git a/node.h b/node.h
index 848ef1b76e..d85f86746a 100644
--- a/node.h
+++ b/node.h
@@ -445,6 +445,9 @@ typedef struct RNode {
 #define NEW_ATTRASGN(r,m,a) NEW_NODE(NODE_ATTRASGN,r,m,a)
 #define NEW_PRELUDE(p,b,o) NEW_NODE(NODE_PRELUDE,p,b,o)
 
+#define NODE_SPECIAL_REQUIRED_KEYWORD ((NODE *)-1)
+#define NODE_SPECIAL_NO_NAME_REST     ((NODE *)-1)
+
 RUBY_SYMBOL_EXPORT_BEGIN
 
 typedef struct node_buffer_struct node_buffer_t;
diff --git a/parse.y b/parse.y
index a608cfa556..e87a0fb22b 100644
--- a/parse.y
+++ b/parse.y
@@ -1804,7 +1804,7 @@ mlhs_basic	: mlhs_head
 		| mlhs_head tSTAR
 		    {
 		    /*%%%*/
-			$$ = new_masgn($1, (NODE *)-1, &@1);
+			$$ = new_masgn($1, NODE_SPECIAL_NO_NAME_REST, &@1);
 		    /*%
 			$$ = mlhs_add_star($1, Qnil);
 		    %*/
@@ -1812,7 +1812,7 @@ mlhs_basic	: mlhs_head
 		| mlhs_head tSTAR ',' mlhs_post
 		    {
 		    /*%%%*/
-			$$ = new_masgn($1, new_postarg((NODE *)-1, $4, &@1), &@1);
+			$$ = new_masgn($1, new_postarg(NODE_SPECIAL_NO_NAME_REST, $4, &@1), &@1);
 		    /*%
 			$1 = mlhs_add_star($1, Qnil);
 			$$ = mlhs_add_post($1, $4);
@@ -1838,7 +1838,7 @@ mlhs_basic	: mlhs_head
 		| tSTAR
 		    {
 		    /*%%%*/
-			$$ = new_masgn(0, (NODE *)-1, &@1);
+			$$ = new_masgn(0, NODE_SPECIAL_NO_NAME_REST, &@1);
 		    /*%
 			$$ = mlhs_add_star(mlhs_new(), Qnil);
 		    %*/
@@ -1846,7 +1846,7 @@ mlhs_basic	: mlhs_head
 		| tSTAR ',' mlhs_post
 		    {
 		    /*%%%*/
-			$$ = new_masgn(0, new_postarg((NODE *)-1, $3, &@1), &@1);
+			$$ = new_masgn(0, new_postarg(NODE_SPECIAL_NO_NAME_REST, $3, &@1), &@1);
 		    /*%
 			$$ = mlhs_add_star(mlhs_new(), Qnil);
 			$$ = mlhs_add_post($$, $3);
@@ -3353,7 +3353,7 @@ f_margs		: f_marg_list
 		| f_marg_list ',' tSTAR
 		    {
 		    /*%%%*/
-			$$ = new_masgn($1, (NODE *)-1, &@1);
+			$$ = new_masgn($1, NODE_SPECIAL_NO_NAME_REST, &@1);
 		    /*%
 			$$ = mlhs_add_star($1, Qnil);
 		    %*/
@@ -3361,7 +3361,7 @@ f_margs		: f_marg_list
 		| f_marg_list ',' tSTAR ',' f_marg_list
 		    {
 		    /*%%%*/
-			$$ = new_masgn($1, new_postarg((NODE *)-1, $5, &@1), &@1);
+			$$ = new_masgn($1, new_postarg(NODE_SPECIAL_NO_NAME_REST, $5, &@1), &@1);
 		    /*%
 			$$ = mlhs_add_star($1, Qnil);
 			$$ = mlhs_add_post($$, $5);
@@ -3389,7 +3389,7 @@ f_margs		: f_marg_list
 		| tSTAR
 		    {
 		    /*%%%*/
-			$$ = new_masgn(0, (NODE *)-1, &@1);
+			$$ = new_masgn(0, NODE_SPECIAL_NO_NAME_REST, &@1);
 		    /*%
 			$$ = mlhs_add_star(mlhs_new(), Qnil);
 		    %*/
@@ -3397,7 +3397,7 @@ f_margs		: f_marg_list
 		| tSTAR ',' f_marg_list
 		    {
 		    /*%%%*/
-			$$ = new_masgn(0, new_postarg((NODE *)-1, $3, &@1), &@1);
+			$$ = new_masgn(0, new_postarg(NODE_SPECIAL_NO_NAME_REST, $3, &@1), &@1);
 		    /*%
 			$$ = mlhs_add_star(mlhs_new(), Qnil);
 			$$ = mlhs_add_post($$, $3);
@@ -4753,7 +4753,7 @@ f_kw		: f_label arg_value
 		| f_label
 		    {
 			current_arg = 0;
-			$$ = assignable($1, (NODE *)-1, &@1);
+			$$ = assignable($1, NODE_SPECIAL_REQUIRED_KEYWORD, &@1);
 		    /*%%%*/
 			$$ = new_kw_arg($$, &@1);
 		    /*%
@@ -4773,7 +4773,7 @@ f_block_kw	: f_label primary_value
 		    }
 		| f_label
 		    {
-			$$ = assignable($1, (NODE *)-1, &@1);
+			$$ = assignable($1, NODE_SPECIAL_REQUIRED_KEYWORD, &@1);
 		    /*%%%*/
 			$$ = new_kw_arg($$, &@1);
 		    /*%
@@ -10836,7 +10836,7 @@ new_args_tail_gen(struct parser_params *parser, NODE *k, ID kr, ID b, YYLTYPE *l
 	    NODE *val_node = kwn->nd_body->nd_value;
 	    ID vid = kwn->nd_body->nd_vid;
 
-	    if (val_node == (NODE *)-1) {
+	    if (val_node == NODE_SPECIAL_REQUIRED_KEYWORD) {
 		vtable_add(required_kw_vars, vid);
 	    }
 	    else {