We have an enum AXIS_INDEX. Use it.

ChangeLog

@@ -5,6 +5,9 @@
 	"set link x2 via f(x) inv g(x)" (primary axis x1).
 	Bug #1973
 
+	* src/graphics.h src/unset.c:  We have an enum AXIS_INDEX. Use it.
+	(mostly to aid debugging; shouldn't affect code generation).
+
 2017-10-08  Ethan A Merritt  <[email protected]>
 
 	* src/axis.c (reconcile_linked_axes) src/axis.h src/plot2d.c:

src/graphics.h

@@ -1,5 +1,5 @@
 /*
- * $Id: graphics.h,v 1.73 2017-09-11 20:13:24 sfeam Exp $
+ * $Id: graphics.h,v 1.74 2017-10-09 20:56:36 sfeam Exp $
  */
 
 /* GNUPLOT - graphics.h */
@@ -43,6 +43,10 @@
 #include "gadgets.h"
 #include "term_api.h"
 
+#ifndef AXIS_INDEX
+#include "axis.h"
+#endif
+
 /* types defined for 2D plotting */
 
 typedef struct curve_points {
@@ -76,9 +80,9 @@ typedef struct curve_points {
     int boxplot_factors;	/* Only used if plot_style == BOXPLOT */
     int p_max;			/* how many points are allocated */
     int p_count;		/* count of points in points */
-    int x_axis;			/* FIRST_X_AXIS or SECOND_X_AXIS */
-    int y_axis;			/* FIRST_Y_AXIS or SECOND_Y_AXIS */
-    int z_axis;			/* same as either x_axis or y_axis, for 5-column plot types */
+    AXIS_INDEX x_axis;		/* FIRST_X_AXIS or SECOND_X_AXIS */
+    AXIS_INDEX y_axis;		/* FIRST_Y_AXIS or SECOND_Y_AXIS */
+    AXIS_INDEX z_axis;		/* same as either x_axis or y_axis, for 5-column plot types */
     int current_plotno;		/* Only used by "pn" option of linespoints */
     int n_par_axes;		/* Only used for parallel axis plots */
     double **z_n;		/* Only used for parallel axis plots */

src/unset.c

@@ -1,5 +1,5 @@
 #ifndef lint
-static char *RCSid() { return RCSid("$Id: unset.c,v 1.258 2017-09-11 20:13:24 sfeam Exp $"); }
+static char *RCSid() { return RCSid("$Id: unset.c,v 1.259 2017-10-09 20:56:36 sfeam Exp $"); }
 #endif
 
 /* GNUPLOT - unset.c */
@@ -721,7 +721,7 @@ unset_autoscale()
     } else {
 	/* HBB 20000506: parse axis name, and unset the right element
 	 * of the array: */
-	int axis = lookup_table(axisname_tbl, c_token);
+	AXIS_INDEX axis = lookup_table(axisname_tbl, c_token);
 	if (axis >= 0) {
 	    axis_array[axis].set_autoscale = AUTOSCALE_NONE;
 	c_token++;