From 3c86a6b93487d9fa321b2a45ca58c5020e374524 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <chfast@gmail.com>
Date: Wed, 29 Aug 2018 23:00:11 +0200
Subject: [PATCH] Return result from call_fn

This changes the evmc_call_fn signature to return evmc_result object instead of getting result as an output parameter.
---
 bindings/go/evmc/host.go       |  4 ++--
 examples/capi.c                |  7 +++----
 include/evmc/evmc.h            | 14 +++++---------
 test/vmtester/mock_context.cpp |  6 ++++--
 4 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/bindings/go/evmc/host.go b/bindings/go/evmc/host.go
index 47f4f63..f3b804b 100644
--- a/bindings/go/evmc/host.go
+++ b/bindings/go/evmc/host.go
@@ -208,7 +208,7 @@ func emitLog(pCtx unsafe.Pointer, pAddr *C.struct_evmc_address, pData unsafe.Poi
 }
 
 //export call
-func call(pResult *C.struct_evmc_result, pCtx unsafe.Pointer, msg *C.struct_evmc_message) {
+func call(pCtx unsafe.Pointer, msg *C.struct_evmc_message) C.struct_evmc_result {
 	idx := int((*C.struct_extended_context)(pCtx).index)
 	ctx := getHostContext(idx)
 
@@ -234,5 +234,5 @@ func call(pResult *C.struct_evmc_result, pCtx unsafe.Pointer, msg *C.struct_evmc
 		result.release = (C.evmc_release_result_fn)(C.evmc_go_free_result_output)
 	}
 
-	*pResult = result
+	return result
 }
diff --git a/examples/capi.c b/examples/capi.c
index 55383bc..8b23226 100644
--- a/examples/capi.c
+++ b/examples/capi.c
@@ -118,13 +118,12 @@ static void selfdestruct(struct evmc_context* context,
     printf("\n");
 }
 
-static void call(struct evmc_result* result,
-                 struct evmc_context* context,
-                 const struct evmc_message* msg)
+static struct evmc_result call(struct evmc_context* context, const struct evmc_message* msg)
 {
     (void)context;
     printf("EVM-C: CALL (depth: %d)\n", msg->depth);
-    result->status_code = EVMC_FAILURE;
+    struct evmc_result result = {.status_code = EVMC_FAILURE};
+    return result;
 }
 
 static void get_tx_context(struct evmc_tx_context* result, struct evmc_context* context)
diff --git a/include/evmc/evmc.h b/include/evmc/evmc.h
index e0c3ce5..bd81912 100644
--- a/include/evmc/evmc.h
+++ b/include/evmc/evmc.h
@@ -574,16 +574,12 @@ typedef void (*evmc_emit_log_fn)(struct evmc_context* context,
 /**
  * Pointer to the callback function supporting EVM calls.
  *
- *  @param[out] result  The result of the call. The result object is not
- *                      initialized by the EVM, the Client MUST correctly
- *                      initialize all expected fields of the structure.
- *  @param      context The pointer to the Host execution context.
- *                      @see ::evmc_context.
- *  @param      msg     Call parameters. @see ::evmc_message.
+ * @param  context The pointer to the Host execution context.
+ * @param  msg     The call parameters.
+ * @return         The result of the call.
  */
-typedef void (*evmc_call_fn)(struct evmc_result* result,
-                             struct evmc_context* context,
-                             const struct evmc_message* msg);
+typedef struct evmc_result (*evmc_call_fn)(struct evmc_context* context,
+                                           const struct evmc_message* msg);
 
 /**
  * The context interface.
diff --git a/test/vmtester/mock_context.cpp b/test/vmtester/mock_context.cpp
index bc59548..eb12f0e 100644
--- a/test/vmtester/mock_context.cpp
+++ b/test/vmtester/mock_context.cpp
@@ -88,11 +88,13 @@ static void selfdestruct(evmc_context* context,
     (void)beneficiary;
 }
 
-static void call(evmc_result* result, evmc_context* context, const evmc_message* msg)
+static evmc_result call(evmc_context* context, const evmc_message* msg)
 {
     (void)context;
     (void)msg;
-    result->status_code = EVMC_FAILURE;
+    evmc_result result{};
+    result.status_code = EVMC_FAILURE;
+    return result;
 }
 
 static void get_tx_context(evmc_tx_context* result, evmc_context* context)