Fix compiler warnings.

This reverts changes made in b0d00823eb96de733510354.  The warnings
are fixed by changing the functions signatures, instead of casting
their pointers.

14 files changed, 129 insertions, 120 deletions

diff --git a/src/bank-lib/bank_api_admin.c b/src/bank-lib/bank_api_admin.c
index a18b95c3f..3a1ec4efa 100644
--- a/src/bank-lib/bank_api_admin.c
+++ b/src/bank-lib/bank_api_admin.c
@@ -70,16 +70,17 @@ struct TALER_BANK_AdminAddIncomingHandle
  *
  * @param cls the `struct TALER_BANK_AdminAddIncomingHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_admin_add_incoming_finished (void *cls,
                                     long response_code,
-                                    const json_t *json)
+                                    const void *response)
 {
   struct TALER_BANK_AdminAddIncomingHandle *aai = cls;
   uint64_t row_id = UINT64_MAX;
   enum TALER_ErrorCode ec;
+  const json_t *j = response;
 
   aai->job = NULL;
   switch (response_code)
@@ -96,7 +97,7 @@ handle_admin_add_incoming_finished (void *cls,
       };
 
       if (GNUNET_OK !=
-          GNUNET_JSON_parse (json,
+          GNUNET_JSON_parse (j,
                              spec,
                              NULL, NULL))
       {
@@ -111,27 +112,27 @@ handle_admin_add_incoming_finished (void *cls,
   case MHD_HTTP_BAD_REQUEST:
     /* This should never happen, either us or the bank is buggy
        (or API version conflict); just pass JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_FORBIDDEN:
     /* Access denied */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_UNAUTHORIZED:
     /* Nothing really to verify, bank says one of the signatures is
        invalid; as we checked them, this should never happen, we
        should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_NOT_FOUND:
     /* Nothing really to verify, this should never
        happen, we should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_INTERNAL_SERVER_ERROR:
     /* Server had an internal issue; we should retry, but this API
        leaves this to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   default:
     /* unexpected response code */
@@ -139,7 +140,7 @@ handle_admin_add_incoming_finished (void *cls,
                 "Unexpected response code %u\n",
                 (unsigned int) response_code);
     GNUNET_break (0);
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     response_code = 0;
     break;
   }
@@ -147,7 +148,7 @@ handle_admin_add_incoming_finished (void *cls,
            response_code,
            ec,
            row_id,
-           json);
+           j);
   TALER_BANK_admin_add_incoming_cancel (aai);
 }
 
@@ -247,7 +248,7 @@ TALER_BANK_admin_add_incoming (struct GNUNET_CURL_Context *ctx,
   aai->job = GNUNET_CURL_job_add (ctx,
                                   eh,
                                   GNUNET_NO,
-                                  (GC_JCC) &handle_admin_add_incoming_finished,
+                                  &handle_admin_add_incoming_finished,
                                   aai);
   return aai;
 }
diff --git a/src/bank-lib/bank_api_history.c b/src/bank-lib/bank_api_history.c
index 46be1085a..844f9b0cd 100644
--- a/src/bank-lib/bank_api_history.c
+++ b/src/bank-lib/bank_api_history.c
@@ -169,15 +169,16 @@ parse_account_history (struct TALER_BANK_HistoryHandle *hh,
  *
  * @param cls the `struct TALER_BANK_HistoryHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_history_finished (void *cls,
                          long response_code,
-                         const json_t *json)
+                         const void *response)
 {
   struct TALER_BANK_HistoryHandle *hh = cls;
   enum TALER_ErrorCode ec;
+  const json_t *j = response;
 
   hh->job = NULL;
   switch (response_code)
@@ -188,7 +189,7 @@ handle_history_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         parse_account_history (hh,
-                               json))
+                               j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -204,27 +205,27 @@ handle_history_finished (void *cls,
   case MHD_HTTP_BAD_REQUEST:
     /* This should never happen, either us or the bank is buggy
        (or API version conflict); just pass JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_FORBIDDEN:
     /* Access denied */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_UNAUTHORIZED:
     /* Nothing really to verify, bank says one of the signatures is
        invalid; as we checked them, this should never happen, we
        should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_NOT_FOUND:
     /* Nothing really to verify, this should never
        happen, we should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_INTERNAL_SERVER_ERROR:
     /* Server had an internal issue; we should retry, but this API
        leaves this to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   default:
     /* unexpected response code */
@@ -232,7 +233,7 @@ handle_history_finished (void *cls,
                 "Unexpected response code %u\n",
                 (unsigned int) response_code);
     GNUNET_break (0);
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     response_code = 0;
     break;
   }
@@ -242,7 +243,7 @@ handle_history_finished (void *cls,
            TALER_BANK_DIRECTION_NONE,
            0LLU,
            NULL,
-           json);
+           j);
   TALER_BANK_history_cancel (hh);
 }
 
@@ -350,7 +351,7 @@ TALER_BANK_history (struct GNUNET_CURL_Context *ctx,
   hh->job = GNUNET_CURL_job_add (ctx,
                                  eh,
                                  GNUNET_NO,
-                                 (GC_JCC) &handle_history_finished,
+                                 &handle_history_finished,
                                  hh);
   return hh;
 }
diff --git a/src/bank-lib/bank_api_reject.c b/src/bank-lib/bank_api_reject.c
index 00a49bd16..5e7a1ac29 100644
--- a/src/bank-lib/bank_api_reject.c
+++ b/src/bank-lib/bank_api_reject.c
@@ -70,15 +70,16 @@ struct TALER_BANK_RejectHandle
  *
  * @param cls the `struct TALER_BANK_RejectHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_reject_finished (void *cls,
                         long response_code,
-                        const json_t *json)
+                        const void *response)
 {
   struct TALER_BANK_RejectHandle *rh = cls;
   enum TALER_ErrorCode ec;
+  const json_t *j = response;
 
   rh->job = NULL;
   switch (response_code)
@@ -97,27 +98,27 @@ handle_reject_finished (void *cls,
   case MHD_HTTP_BAD_REQUEST:
     /* This should never happen, either us or the bank is buggy
        (or API version conflict); just pass JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_FORBIDDEN:
     /* Access denied */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_UNAUTHORIZED:
     /* Nothing really to verify, bank says one of the signatures is
        invalid; as we checked them, this should never happen, we
        should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_NOT_FOUND:
     /* Nothing really to verify, this should never
        happen, we should pass the JSON reply to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   case MHD_HTTP_INTERNAL_SERVER_ERROR:
     /* Server had an internal issue; we should retry, but this API
        leaves this to the application */
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     break;
   default:
     /* unexpected response code */
@@ -125,7 +126,7 @@ handle_reject_finished (void *cls,
                 "Unexpected response code %u\n",
                 (unsigned int) response_code);
     GNUNET_break (0);
-    ec = TALER_BANK_parse_ec_ (json);
+    ec = TALER_BANK_parse_ec_ (j);
     response_code = 0;
     break;
   }
@@ -215,7 +216,7 @@ TALER_BANK_reject (struct GNUNET_CURL_Context *ctx,
   rh->job = GNUNET_CURL_job_add (ctx,
                                  eh,
                                  GNUNET_NO,
-                                 (GC_JCC) &handle_reject_finished,
+                                 &handle_reject_finished,
                                  rh);
   return rh;
 }
diff --git a/src/exchange-lib/exchange_api_deposit.c b/src/exchange-lib/exchange_api_deposit.c
index 71a1f2d68..c388e6816 100644
--- a/src/exchange-lib/exchange_api_deposit.c
+++ b/src/exchange-lib/exchange_api_deposit.c
@@ -193,16 +193,17 @@ verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *d
  *
  * @param cls the `struct TALER_EXCHANGE_DepositHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_deposit_finished (void *cls,
                          long response_code,
-                         const json_t *json)
+                         const void *response)
 {
   struct TALER_EXCHANGE_DepositHandle *dh = cls;
   struct TALER_ExchangePublicKeyP exchange_pub;
   struct TALER_ExchangePublicKeyP *ep = NULL;
+  const json_t *j = response;
 
   dh->job = NULL;
   switch (response_code)
@@ -212,7 +213,7 @@ handle_deposit_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_deposit_signature_ok (dh,
-                                     json,
+                                     j,
                                      &exchange_pub))
     {
       GNUNET_break_op (0);
@@ -231,7 +232,7 @@ handle_deposit_finished (void *cls,
     /* Double spending; check signatures on transaction history */
     if (GNUNET_OK !=
         verify_deposit_signature_forbidden (dh,
-                                            json))
+                                            j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -261,9 +262,9 @@ handle_deposit_finished (void *cls,
   }
   dh->cb (dh->cb_cls,
           response_code,
-	  TALER_JSON_get_error_code (json),
+	  TALER_JSON_get_error_code (j),
           ep,
-          json);
+          j);
   TALER_EXCHANGE_deposit_cancel (dh);
 }
 
@@ -511,7 +512,7 @@ TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange,
   dh->job = GNUNET_CURL_job_add (ctx,
 				 eh,
 				 GNUNET_YES,
-				 (GC_JCC) &handle_deposit_finished,
+				 &handle_deposit_finished,
 				 dh);
   return dh;
 }
diff --git a/src/exchange-lib/exchange_api_handle.c b/src/exchange-lib/exchange_api_handle.c
index eb81a79fa..27ee257d9 100644
--- a/src/exchange-lib/exchange_api_handle.c
+++ b/src/exchange-lib/exchange_api_handle.c
@@ -834,13 +834,14 @@ TALER_EXCHANGE_check_keys_current (struct TALER_EXCHANGE_Handle *exchange,
 static void
 keys_completed_cb (void *cls,
                    long response_code,
-                   const json_t *resp_obj)
+                   const void *resp_obj)
 {
   struct KeysRequest *kr = cls;
   struct TALER_EXCHANGE_Handle *exchange = kr->exchange;
   struct TALER_EXCHANGE_Keys kd;
   struct TALER_EXCHANGE_Keys kd_old;
   enum TALER_EXCHANGE_VersionCompatibility vc;
+  const json_t *j = resp_obj;
 
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Received keys from URL `%s' with status %ld.\n",
@@ -863,7 +864,7 @@ keys_completed_cb (void *cls,
                                                          exchange);
     return;
   case MHD_HTTP_OK:
-    if (NULL == resp_obj)
+    if (NULL == j)
     {
       response_code = 0;
       break;
@@ -902,7 +903,7 @@ keys_completed_cb (void *cls,
     }
 
     if (GNUNET_OK !=
-        decode_keys_json (resp_obj,
+        decode_keys_json (j,
 			  GNUNET_YES,
                           &kd,
 			  &vc))
@@ -927,7 +928,7 @@ keys_completed_cb (void *cls,
       break;
     }
     json_decref (exchange->key_data_raw);
-    exchange->key_data_raw = json_deep_copy (resp_obj);
+    exchange->key_data_raw = json_deep_copy (j);
     exchange->retry_delay = GNUNET_TIME_UNIT_ZERO;
     break;
   default:
@@ -1484,7 +1485,7 @@ request_keys (void *cls)
   kr->job = GNUNET_CURL_job_add (exchange->ctx,
                                  eh,
                                  GNUNET_NO,
-                                 (GC_JCC) &keys_completed_cb,
+                                 &keys_completed_cb,
                                  kr);
   exchange->kr = kr;
 }
diff --git a/src/exchange-lib/exchange_api_payback.c b/src/exchange-lib/exchange_api_payback.c
index 79eb55838..5bfed2cfe 100644
--- a/src/exchange-lib/exchange_api_payback.c
+++ b/src/exchange-lib/exchange_api_payback.c
@@ -158,14 +158,15 @@ verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph,
  *
  * @param cls the `struct TALER_EXCHANGE_PaybackHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_payback_finished (void *cls,
                          long response_code,
-                         const json_t *json)
+                         const void *response)
 {
   struct TALER_EXCHANGE_PaybackHandle *ph = cls;
+  const json_t *j = response;
 
   ph->job = NULL;
   switch (response_code)
@@ -175,7 +176,7 @@ handle_payback_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_payback_signature_ok (ph,
-                                     json))
+                                     j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -194,7 +195,7 @@ handle_payback_finished (void *cls,
       const struct TALER_EXCHANGE_DenomPublicKey *dki;
 
       dki = ph->pk;
-      history = json_object_get (json,
+      history = json_object_get (j,
 				 "history");
       if (GNUNET_OK !=
 	  TALER_EXCHANGE_verify_coin_history (dki->fee_deposit.currency,
@@ -207,11 +208,11 @@ handle_payback_finished (void *cls,
       }
       ph->cb (ph->cb_cls,
 	      response_code,
-	      TALER_JSON_get_error_code (json),
+	      TALER_JSON_get_error_code (j),
 	      &total,
 	      GNUNET_TIME_UNIT_FOREVER_ABS,
 	      NULL,
-	      json);
+	      j);
       TALER_EXCHANGE_payback_cancel (ph);
       return;
     }
@@ -243,11 +244,11 @@ handle_payback_finished (void *cls,
   }
   ph->cb (ph->cb_cls,
           response_code,
-	  TALER_JSON_get_error_code (json),
+	  TALER_JSON_get_error_code (j),
           NULL,
           GNUNET_TIME_UNIT_FOREVER_ABS,
           NULL,
-          json);
+          j);
   TALER_EXCHANGE_payback_cancel (ph);
 }
 
@@ -344,7 +345,7 @@ TALER_EXCHANGE_payback (struct TALER_EXCHANGE_Handle *exchange,
   ph->job = GNUNET_CURL_job_add (ctx,
 				 eh,
 				 GNUNET_YES,
-				 (GC_JCC) &handle_payback_finished,
+				 &handle_payback_finished,
 				 ph);
   return ph;
 }
diff --git a/src/exchange-lib/exchange_api_refresh.c b/src/exchange-lib/exchange_api_refresh.c
index 035d9d6da..443ba7d23 100644
--- a/src/exchange-lib/exchange_api_refresh.c
+++ b/src/exchange-lib/exchange_api_refresh.c
@@ -1032,16 +1032,17 @@ verify_refresh_melt_signature_forbidden (struct TALER_EXCHANGE_RefreshMeltHandle
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshMeltHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_refresh_melt_finished (void *cls,
                               long response_code,
-                              const json_t *json)
+                              const void *response)
 {
   struct TALER_EXCHANGE_RefreshMeltHandle *rmh = cls;
   uint32_t noreveal_index = TALER_CNC_KAPPA; /* invalid value */
   struct TALER_ExchangePublicKeyP exchange_pub;
+  const json_t *j = response;
 
   rmh->job = NULL;
   switch (response_code)
@@ -1051,7 +1052,7 @@ handle_refresh_melt_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_refresh_melt_signature_ok (rmh,
-                                          json,
+                                          j,
                                           &exchange_pub,
                                           &noreveal_index))
     {
@@ -1062,10 +1063,10 @@ handle_refresh_melt_finished (void *cls,
     {
       rmh->melt_cb (rmh->melt_cb_cls,
                     response_code,
-		    TALER_JSON_get_error_code (json),
+		    TALER_JSON_get_error_code (j),
                     noreveal_index,
                     (0 == response_code) ? NULL : &exchange_pub,
-                    json);
+                    j);
       rmh->melt_cb = NULL;
     }
     break;
@@ -1077,7 +1078,7 @@ handle_refresh_melt_finished (void *cls,
     /* Double spending; check signatures on transaction history */
     if (GNUNET_OK !=
         verify_refresh_melt_signature_forbidden (rmh,
-                                                 json))
+                                                 j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -1108,10 +1109,10 @@ handle_refresh_melt_finished (void *cls,
   if (NULL != rmh->melt_cb)
     rmh->melt_cb (rmh->melt_cb_cls,
                   response_code,
-		  TALER_JSON_get_error_code (json),
+		  TALER_JSON_get_error_code (j),
                   UINT32_MAX,
                   NULL,
-                  json);
+                  j);
   TALER_EXCHANGE_refresh_melt_cancel (rmh);
 }
 
@@ -1218,7 +1219,7 @@ TALER_EXCHANGE_refresh_melt (struct TALER_EXCHANGE_Handle *exchange,
   rmh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
-                          (GC_JCC) &handle_refresh_melt_finished,
+                          &handle_refresh_melt_finished,
                           rmh);
   return rmh;
 }
@@ -1411,14 +1412,15 @@ refresh_reveal_ok (struct TALER_EXCHANGE_RefreshRevealHandle *rrh,
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_refresh_reveal_finished (void *cls,
                                 long response_code,
-                                const json_t *json)
+                                const void *response)
 {
   struct TALER_EXCHANGE_RefreshRevealHandle *rrh = cls;
+  const json_t *j = response;
 
   rrh->job = NULL;
   switch (response_code)
@@ -1433,7 +1435,7 @@ handle_refresh_reveal_finished (void *cls,
 
       memset (sigs, 0, sizeof (sigs));
       ret = refresh_reveal_ok (rrh,
-                               json,
+                               j,
                                coin_privs,
                                sigs);
       if (GNUNET_OK != ret)
@@ -1448,7 +1450,7 @@ handle_refresh_reveal_finished (void *cls,
                         rrh->md->num_fresh_coins,
                         coin_privs,
                         sigs,
-                        json);
+                        j);
         rrh->reveal_cb = NULL;
       }
       for (unsigned int i=0;i<rrh->md->num_fresh_coins;i++)
@@ -1481,11 +1483,11 @@ handle_refresh_reveal_finished (void *cls,
   if (NULL != rrh->reveal_cb)
     rrh->reveal_cb (rrh->reveal_cb_cls,
                     response_code,
-		    TALER_JSON_get_error_code (json),
+		    TALER_JSON_get_error_code (j),
 		    0,
 		    NULL,
 		    NULL,
-                    json);
+                    j);
   TALER_EXCHANGE_refresh_reveal_cancel (rrh);
 }
 
@@ -1645,7 +1647,7 @@ TALER_EXCHANGE_refresh_reveal (struct TALER_EXCHANGE_Handle *exchange,
   rrh->job = GNUNET_CURL_job_add (ctx,
                                   eh,
                                   GNUNET_YES,
-                                  (GC_JCC) &handle_refresh_reveal_finished,
+                                  &handle_refresh_reveal_finished,
                                   rrh);
   return rrh;
 }
diff --git a/src/exchange-lib/exchange_api_refresh_link.c b/src/exchange-lib/exchange_api_refresh_link.c
index f882491ea..545c96a7c 100644
--- a/src/exchange-lib/exchange_api_refresh_link.c
+++ b/src/exchange-lib/exchange_api_refresh_link.c
@@ -301,14 +301,15 @@ parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
  *
  * @param cls the `struct TALER_EXCHANGE_RefreshLinkHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_refresh_link_finished (void *cls,
                               long response_code,
-                              const json_t *json)
+                              const void *response)
 {
   struct TALER_EXCHANGE_RefreshLinkHandle *rlh = cls;
+  const json_t *j = response;
 
   rlh->job = NULL;
   switch (response_code)
@@ -318,7 +319,7 @@ handle_refresh_link_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         parse_refresh_link_ok (rlh,
-                               json))
+                               j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -348,12 +349,12 @@ handle_refresh_link_finished (void *cls,
   if (NULL != rlh->link_cb)
     rlh->link_cb (rlh->link_cb_cls,
                   response_code,
-		  TALER_JSON_get_error_code (json),
+		  TALER_JSON_get_error_code (j),
                   0,
 		  NULL,
 		  NULL,
 		  NULL,
-                  json);
+                  j);
   TALER_EXCHANGE_refresh_link_cancel (rlh);
 }
 
@@ -415,7 +416,7 @@ TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
   rlh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
-                          (GC_JCC) &handle_refresh_link_finished,
+                          &handle_refresh_link_finished,
                           rlh);
   return rlh;
 }
diff --git a/src/exchange-lib/exchange_api_refund.c b/src/exchange-lib/exchange_api_refund.c
index 80eed74dc..1f1e66942 100644
--- a/src/exchange-lib/exchange_api_refund.c
+++ b/src/exchange-lib/exchange_api_refund.c
@@ -133,16 +133,17 @@ verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
  *
  * @param cls the `struct TALER_EXCHANGE_RefundHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_refund_finished (void *cls,
                         long response_code,
-                        const json_t *json)
+                        const void *response)
 {
   struct TALER_EXCHANGE_RefundHandle *rh = cls;
   struct TALER_ExchangePublicKeyP exchange_pub;
   struct TALER_ExchangePublicKeyP *ep = NULL;
+  const json_t *j = response;
 
   rh->job = NULL;
   switch (response_code)
@@ -152,7 +153,7 @@ handle_refund_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         verify_refund_signature_ok (rh,
-				    json,
+				    j,
                                     &exchange_pub))
     {
       GNUNET_break_op (0);
@@ -203,9 +204,9 @@ handle_refund_finished (void *cls,
   }
   rh->cb (rh->cb_cls,
           response_code,
-	  TALER_JSON_get_error_code (json),
+	  TALER_JSON_get_error_code (j),
           ep,
-          json);
+          j);
   TALER_EXCHANGE_refund_cancel (rh);
 }
 
@@ -386,7 +387,7 @@ refund_obj = json_pack ("{s:o, s:o," /* amount/fee */
   rh->job = GNUNET_CURL_job_add (ctx,
 				 eh,
 				 GNUNET_YES,
-				 (GC_JCC) &handle_refund_finished,
+				 &handle_refund_finished,
 				 rh);
   return rh;
 }
diff --git a/src/exchange-lib/exchange_api_reserve.c b/src/exchange-lib/exchange_api_reserve.c
index 1f9a3a36e..99e7588c0 100644
--- a/src/exchange-lib/exchange_api_reserve.c
+++ b/src/exchange-lib/exchange_api_reserve.c
@@ -456,14 +456,15 @@ free_rhistory (struct TALER_EXCHANGE_ReserveHistory *rhistory,
  *
  * @param cls the `struct TALER_EXCHANGE_ReserveStatusHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_reserve_status_finished (void *cls,
                                 long response_code,
-                                const json_t *json)
+                                const void *response)
 {
   struct TALER_EXCHANGE_ReserveStatusHandle *rsh = cls;
+  const json_t *j = response;
 
   rsh->job = NULL;
   switch (response_code)
@@ -483,7 +484,7 @@ handle_reserve_status_finished (void *cls,
       };
 
       if (GNUNET_OK !=
-          GNUNET_JSON_parse (json,
+          GNUNET_JSON_parse (j,
                              spec,
                              NULL,
 			     NULL))
@@ -492,7 +493,7 @@ handle_reserve_status_finished (void *cls,
         response_code = 0;
         break;
       }
-      history = json_object_get (json,
+      history = json_object_get (j,
                                  "history");
       if (NULL == history)
       {
@@ -531,7 +532,7 @@ handle_reserve_status_finished (void *cls,
           rsh->cb (rsh->cb_cls,
                    response_code,
                    TALER_EC_NONE,
-                   json,
+                   j,
                    &balance,
                    len,
                    rhistory);
@@ -567,8 +568,8 @@ handle_reserve_status_finished (void *cls,
   {
     rsh->cb (rsh->cb_cls,
              response_code,
-	     TALER_JSON_get_error_code (json),
-             json,
+	     TALER_JSON_get_error_code (j),
+             j,
              NULL,
              0, NULL);
     rsh->cb = NULL;
@@ -631,7 +632,7 @@ TALER_EXCHANGE_reserve_status (struct TALER_EXCHANGE_Handle *exchange,
   rsh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_NO,
-                          (GC_JCC) &handle_reserve_status_finished,
+                          &handle_reserve_status_finished,
                           rsh);
   return rsh;
 }
@@ -891,14 +892,15 @@ reserve_withdraw_payment_required (struct TALER_EXCHANGE_ReserveWithdrawHandle *
  *
  * @param cls the `struct TALER_EXCHANGE_ReserveWithdrawHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_reserve_withdraw_finished (void *cls,
                                   long response_code,
-                                  const json_t *json)
+                                  const void *response)
 {
   struct TALER_EXCHANGE_ReserveWithdrawHandle *wsh = cls;
+  const json_t *j = response;
 
   wsh->job = NULL;
   switch (response_code)
@@ -908,7 +910,7 @@ handle_reserve_withdraw_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK !=
         reserve_withdraw_ok (wsh,
-                             json))
+                             j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -923,7 +925,7 @@ handle_reserve_withdraw_finished (void *cls,
        check the signatures in the history... */
     if (GNUNET_OK !=
         reserve_withdraw_payment_required (wsh,
-                                           json))
+                                           j))
     {
       GNUNET_break_op (0);
       response_code = 0;
@@ -958,9 +960,9 @@ handle_reserve_withdraw_finished (void *cls,
   {
     wsh->cb (wsh->cb_cls,
              response_code,
-	     TALER_JSON_get_error_code (json),
+	     TALER_JSON_get_error_code (j),
              NULL,
-             json);
+             j);
     wsh->cb = NULL;
   }
   TALER_EXCHANGE_reserve_withdraw_cancel (wsh);
@@ -1039,7 +1041,7 @@ reserve_withdraw_internal (struct TALER_EXCHANGE_Handle *exchange,
   wsh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
-                          (GC_JCC) &handle_reserve_withdraw_finished,
+                          &handle_reserve_withdraw_finished,
                           wsh);
   return wsh;
 }
diff --git a/src/exchange-lib/exchange_api_track_transaction.c b/src/exchange-lib/exchange_api_track_transaction.c
index 9027acf52..0d9f97ee4 100644
--- a/src/exchange-lib/exchange_api_track_transaction.c
+++ b/src/exchange-lib/exchange_api_track_transaction.c
@@ -134,12 +134,12 @@ verify_deposit_wtid_signature_ok (const struct TALER_EXCHANGE_TrackTransactionHa
  *
  * @param cls the `struct TALER_EXCHANGE_TrackTransactionHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_deposit_wtid_finished (void *cls,
                               long response_code,
-                              const json_t *json)
+                              const void *response)
 {
   struct TALER_EXCHANGE_TrackTransactionHandle *dwh = cls;
   const struct TALER_WireTransferIdentifierRawP *wtid = NULL;
@@ -148,6 +148,7 @@ handle_deposit_wtid_finished (void *cls,
   struct TALER_Amount coin_contribution_s;
   struct TALER_ExchangePublicKeyP exchange_pub;
   struct TALER_ExchangePublicKeyP *ep = NULL;
+  const json_t *j = response;
 
   dwh->job = NULL;
   switch (response_code)
@@ -164,7 +165,7 @@ handle_deposit_wtid_finished (void *cls,
       };
 
       if (GNUNET_OK !=
-          GNUNET_JSON_parse (json,
+          GNUNET_JSON_parse (j,
                              spec,
                              NULL, NULL))
       {
@@ -179,7 +180,7 @@ handle_deposit_wtid_finished (void *cls,
       coin_contribution = &coin_contribution_s;
       if (GNUNET_OK !=
           verify_deposit_wtid_signature_ok (dwh,
-                                            json,
+                                            j,
                                             &exchange_pub))
       {
         GNUNET_break_op (0);
@@ -200,7 +201,7 @@ handle_deposit_wtid_finished (void *cls,
       };
 
       if (GNUNET_OK !=
-          GNUNET_JSON_parse (json,
+          GNUNET_JSON_parse (j,
                              spec,
                              NULL, NULL))
       {
@@ -238,9 +239,9 @@ handle_deposit_wtid_finished (void *cls,
   }
   dwh->cb (dwh->cb_cls,
            response_code,
-	   TALER_JSON_get_error_code (json),
+	   TALER_JSON_get_error_code (j),
            ep,
-           json,
+           j,
            wtid,
            execution_time,
            coin_contribution);
@@ -337,7 +338,7 @@ TALER_EXCHANGE_track_transaction (struct TALER_EXCHANGE_Handle *exchange,
   dwh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
-                          (GC_JCC) &handle_deposit_wtid_finished,
+                          &handle_deposit_wtid_finished,
                           dwh);
   return dwh;
 }
diff --git a/src/exchange-lib/exchange_api_track_transfer.c b/src/exchange-lib/exchange_api_track_transfer.c
index 5d46ffa5a..7d4c92f7c 100644
--- a/src/exchange-lib/exchange_api_track_transfer.c
+++ b/src/exchange-lib/exchange_api_track_transfer.c
@@ -248,14 +248,15 @@ check_track_transfer_response_ok (struct TALER_EXCHANGE_TrackTransferHandle *wdh
  *
  * @param cls the `struct TALER_EXCHANGE_TrackTransferHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_track_transfer_finished (void *cls,
                                 long response_code,
-                                const json_t *json)
+                                const void *response)
 {
   struct TALER_EXCHANGE_TrackTransferHandle *wdh = cls;
+  const json_t *j = response;
 
   wdh->job = NULL;
   switch (response_code)
@@ -265,7 +266,7 @@ handle_track_transfer_finished (void *cls,
   case MHD_HTTP_OK:
     if (GNUNET_OK ==
         check_track_transfer_response_ok (wdh,
-                                          json))
+                                          j))
       return;
     GNUNET_break_op (0);
     response_code = 0;
@@ -298,9 +299,9 @@ handle_track_transfer_finished (void *cls,
   }
   wdh->cb (wdh->cb_cls,
            response_code,
-	   TALER_JSON_get_error_code (json),
+	   TALER_JSON_get_error_code (j),
            NULL,
-           json,
+           j,
            NULL,
            GNUNET_TIME_UNIT_ZERO_ABS,
            NULL,
@@ -359,7 +360,7 @@ TALER_EXCHANGE_track_transfer (struct TALER_EXCHANGE_Handle *exchange,
   wdh->job = GNUNET_CURL_job_add (ctx,
                           eh,
                           GNUNET_YES,
-                          (GC_JCC) &handle_track_transfer_finished,
+                          &handle_track_transfer_finished,
                           wdh);
   return wdh;
 }
diff --git a/src/exchange-lib/exchange_api_wire.c b/src/exchange-lib/exchange_api_wire.c
index ef64a777b..894fd4944 100644
--- a/src/exchange-lib/exchange_api_wire.c
+++ b/src/exchange-lib/exchange_api_wire.c
@@ -202,15 +202,16 @@ lookup_fee (const struct FeeMap *fm,
  *
  * @param cls the `struct TALER_EXCHANGE_WireHandle`
  * @param response_code HTTP response code, 0 on error
- * @param json parsed JSON result, NULL on error
+ * @param response parsed JSON result, NULL on error
  */
 static void
 handle_wire_finished (void *cls,
                       long response_code,
-                      const json_t *json)
+                      const void *response)
 {
   struct TALER_EXCHANGE_WireHandle *wh = cls;
   enum TALER_ErrorCode ec;
+  const json_t *j = response;
 
   wh->job = NULL;
   ec = TALER_EC_NONE;
@@ -232,7 +233,7 @@ handle_wire_finished (void *cls,
       };
 
       if (GNUNET_OK !=
-          GNUNET_JSON_parse (json,
+          GNUNET_JSON_parse (j,
                              spec,
                              NULL, NULL))
       {
@@ -359,7 +360,7 @@ handle_wire_finished (void *cls,
   if (NULL != wh->cb)
     wh->cb (wh->cb_cls,
             response_code,
-            (0 == response_code) ? ec : TALER_JSON_get_error_code (json),
+            (0 == response_code) ? ec : TALER_JSON_get_error_code (j),
             0,
             NULL);
   TALER_EXCHANGE_wire_cancel (wh);
@@ -412,7 +413,7 @@ TALER_EXCHANGE_wire (struct TALER_EXCHANGE_Handle *exchange,
   wh->job = GNUNET_CURL_job_add (ctx,
                          eh,
                          GNUNET_YES,
-                         (GC_JCC) &handle_wire_finished,
+                         &handle_wire_finished,
                          wh);
   return wh;
 }
diff --git a/src/include/taler_json_lib.h b/src/include/taler_json_lib.h
index 3d4b944a6..53dbec3cf 100644
--- a/src/include/taler_json_lib.h
+++ b/src/include/taler_json_lib.h
@@ -37,12 +37,6 @@
               "JSON parsing failed at %s:%u: %s (%s)\n",                  \
               __FILE__, __LINE__, error.text, error.source)
 
-
-/**
- * A shorter name to make type casts less verbose.
- */
-typedef GNUNET_CURL_JobCompletionCallback GC_JCC;
-
 /**
  * Convert a TALER amount to a JSON object.
  *