Windows: Output an error message on calls to libusb_get_pollfds()

Signed-off-by: Michael Plante <michael.plante@gmail.com>

diff --git a/libusb/io.c b/libusb/io.c
index 58bdcdf..c4b3635 100644 (file)
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -2397,6 +2397,8 @@ out:
        usbi_mutex_unlock(&ctx->pollfds_lock);
        return (const struct libusb_pollfd **) ret;
 #else
+       usbi_err(ctx, "external polling of libusb's internal descriptors "\
+               "is not yet supported on Windows platforms");
        return NULL;
 #endif
 }