GMT_IN or GMT_IN|GMT_IS_REFERENCE for external vectors? #3515
Description
The issue was first reported in GenericMappingTools/pygmt#406. The PyGMT script plots two vectors, and PyGMT crashes when plotting the second one.
Here is an equivalent C code, which mimics what PyGMT does.
#include "gmt.h"
int main () {
void *API = NULL; /* The API control structure */
struct GMT_VECTOR *V = NULL; /* Structure to hold input dataset as vectors */
char input[GMT_VF_LEN] = {""}; /* String to hold virtual input filename */
char args[128] = {""}; /* String to hold module command arguments */
uint64_t dim[4] = {2, 2, 1, 0};
double x[2] = {5.0, 5.0};
double y[2] = {3.0, 8.0};
/* Initialize the GMT session */
API = GMT_Create_Session ("test", 2U, GMT_SESSION_EXTERNAL, NULL);
/* Create a dataset */
if ((V = GMT_Create_Data (API, GMT_IS_DATASET|GMT_VIA_VECTOR, GMT_IS_POINT, GMT_CONTAINER_ONLY, dim, NULL, NULL, 0, 0, NULL)) == NULL) return (EXIT_FAILURE);
/**/
GMT_Put_Vector(API, V, 0, GMT_DOUBLE, x);
GMT_Put_Vector(API, V, 1, GMT_DOUBLE, y);
/* Associate our data table with a virtual file */
//GMT_Open_VirtualFile (API, GMT_IS_DATASET|GMT_VIA_VECTOR, GMT_IS_POINT, GMT_IN|GMT_IS_REFERENCE, V, input);
GMT_Open_VirtualFile (API, GMT_IS_DATASET|GMT_VIA_VECTOR, GMT_IS_POINT, GMT_IN, V, input);
/* Prepare the module arguments */
sprintf (args, "%s -JX10c -R0/10/0/10 -Baf -W1p,black+ve0.2c -P -Vd > vectors.ps", input);
/* Call the psxy module */
GMT_Call_Module (API, "psxy", GMT_MODULE_CMD, args);
GMT_Close_VirtualFile (API, input);
/* Destroy the GMT session */
if (GMT_Destroy_Session (API)) return EXIT_FAILURE;
};The C code crashes at this line
Line 415 in e5b54a4
However, if I change the parameter GMT_IN to GMT_IN|GMT_IS_REFERENCE when calling GMT_Open_VirtualFile, it works fine.
Is it a bug in function gmtvector_fix_up_path_cartesian? What's the difference between GMT_IN to GMT_IN|GMT_IS_REFERENCE? Should PyGMT always uses GMT_IN|GMT_IS_REFERENCE?