Store experimental flag in metadata CBOR

3 files changed, 37 insertions, 0 deletions

diff --git a/Changelog.md b/Changelog.md
index 0381d434..3f3d2e98 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -2,6 +2,8 @@
 
 Features:
  * Parser: Display previous visibility specifier in error if multiple are found.
+ * Syntax Checker: Support ``pragma experimental <feature>;`` to turn on experimental features.
+ * Metadata: Store experimental flag in metadata CBOR.
 
 Bugfixes:
 
diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 7c66a843..bc52ff7a 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -653,6 +653,12 @@ void CompilerStack::compileContract(
 		// CBOR-encoding of {"bzzr0": dev::swarmHash(metadata)}
 		bytes{0xa1, 0x65, 'b', 'z', 'z', 'r', '0', 0x58, 0x20} +
 		dev::swarmHash(metadata).asBytes();
+	if (!_contract.sourceUnit().annotation().experimentalFeatures.empty())
+		cborEncodedMetadata =
+		// CBOR-encoding of {"bzzr0": dev::swarmHash(metadata), "experimental": true}
+		bytes{0xa2, 0x65, 'b', 'z', 'z', 'r', '0', 0x58, 0x20} +
+		dev::swarmHash(metadata).asBytes() +
+		bytes{0x6c, 'e', 'x', 'p', 'e', 'r', 'i', 'm', 'e', 'n', 't', 'a', 'l', 0xf5};
 	solAssert(cborEncodedMetadata.size() <= 0xffff, "Metadata too large");
 	// 16-bit big endian length
 	cborEncodedMetadata += toCompactBigEndian(cborEncodedMetadata.size(), 2);
diff --git a/test/libsolidity/Metadata.cpp b/test/libsolidity/Metadata.cpp
index 0d3caddd..77679a32 100644
--- a/test/libsolidity/Metadata.cpp
+++ b/test/libsolidity/Metadata.cpp
@@ -58,6 +58,35 @@ BOOST_AUTO_TEST_CASE(metadata_stamp)
 	BOOST_CHECK(std::equal(expectation.begin(), expectation.end(), bytecode.end() - metadataCBORSize - 2));
 }
 
+BOOST_AUTO_TEST_CASE(metadata_stamp_experimental)
+{
+	// Check that the metadata stamp is at the end of the runtime bytecode.
+	char const* sourceCode = R"(
+		pragma solidity >=0.0;
+		pragma experimental __test;
+		contract test {
+			function g(function(uint) external returns (uint) x) {}
+		}
+	)";
+	CompilerStack compilerStack;
+	compilerStack.addSource("", std::string(sourceCode));
+	compilerStack.setOptimiserSettings(dev::test::Options::get().optimize);
+	ETH_TEST_REQUIRE_NO_THROW(compilerStack.compile(), "Compiling contract failed");
+	bytes const& bytecode = compilerStack.runtimeObject("test").bytecode;
+	std::string const& metadata = compilerStack.metadata("test");
+	BOOST_CHECK(dev::test::isValidMetadata(metadata));
+	bytes hash = dev::swarmHash(metadata).asBytes();
+	BOOST_REQUIRE(hash.size() == 32);
+	BOOST_REQUIRE(bytecode.size() >= 2);
+	size_t metadataCBORSize = (size_t(bytecode.end()[-2]) << 8) + size_t(bytecode.end()[-1]);
+	BOOST_REQUIRE(metadataCBORSize < bytecode.size() - 2);
+	bytes expectation =
+		bytes{0xa2, 0x65, 'b', 'z', 'z', 'r', '0', 0x58, 0x20} +
+		hash +
+		bytes{0x6c, 'e', 'x', 'p', 'e', 'r', 'i', 'm', 'e', 'n', 't', 'a', 'l', 0xf5};
+	BOOST_CHECK(std::equal(expectation.begin(), expectation.end(), bytecode.end() - metadataCBORSize - 2));
+}
+
 BOOST_AUTO_TEST_CASE(metadata_relevant_sources)
 {
 	CompilerStack compilerStack;