Merge pull request #281 from ethereum/fix_result_raw

cpp: Fix evmc::result::raw()

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## [6.2.2] - unreleased
+
+- Fixed: [[#281](https://github.com/ethereum/evmc/pull/281)]
+  Compilation error of evmc::result::raw() in Visual Studio fixed.
+
 ## [6.2.1] - 2019-04-29
 
 - Fixed:

include/evmc/evmc.hpp

@@ -56,8 +56,8 @@ public:
     /// releases the ownership of the resources and invalidates this object.
     evmc_result raw() noexcept
     {
-        auto out = evmc_result{};
-        std::swap<evmc_result>(out, *this);
+        const auto out = evmc_result{*this};  // Copy data.
+        this->release = nullptr;              // Disable releasing of this object.
         return out;
     }
 };

test/unittests/test_cpp.cpp

@@ -2,6 +2,10 @@
 // Copyright 2018-2019 The EVMC Authors.
 // Licensed under the Apache License, Version 2.0.
 
+// The vector is not used here, but including it was causing compilation issues
+// previously related to using explicit template argument (SFINAE disabled).
+#include <vector>
+
 #include "../../examples/example_host.h"
 #include "../../examples/example_vm.h"
 
@@ -120,3 +124,40 @@ TEST(cpp, host_call)
 
     example_host_destroy_context(host_context);
 }
+
+TEST(cpp, result_raii)
+{
+    static auto release_called = 0;
+    release_called = 0;
+    auto release_fn = [](const evmc_result*) noexcept { ++release_called; };
+
+    {
+        auto raw_result = evmc_result{};
+        raw_result.status_code = EVMC_INTERNAL_ERROR;
+        raw_result.release = release_fn;
+
+        auto raii_result = evmc::result{raw_result};
+        EXPECT_EQ(raii_result.status_code, EVMC_INTERNAL_ERROR);
+        EXPECT_EQ(raii_result.gas_left, 0);
+        raii_result.gas_left = -1;
+
+        auto raw_result2 = raii_result.raw();
+        EXPECT_EQ(raw_result2.status_code, EVMC_INTERNAL_ERROR);
+        EXPECT_EQ(raw_result.status_code, EVMC_INTERNAL_ERROR);
+        EXPECT_EQ(raw_result2.gas_left, -1);
+        EXPECT_EQ(raw_result.gas_left, 0);
+        EXPECT_EQ(raw_result2.release, release_fn);
+        EXPECT_EQ(raw_result.release, release_fn);
+    }
+    EXPECT_EQ(release_called, 0);
+
+    {
+        auto raw_result = evmc_result{};
+        raw_result.status_code = EVMC_INTERNAL_ERROR;
+        raw_result.release = release_fn;
+
+        auto raii_result = evmc::result{raw_result};
+        EXPECT_EQ(raii_result.status_code, EVMC_INTERNAL_ERROR);
+    }
+    EXPECT_EQ(release_called, 1);
+}