Merge pull request #6097 from ethereum/meta-name

Provide access to the name of contracts.

Changelog.md

@@ -1,6 +1,7 @@
 ### 0.5.5 (unreleased)
 
 Language Features:
+ * Meta programming: Provide access to the name of contracts via ``type(C).name``.
 
 
 Compiler Features:

libsolidity/analysis/TypeChecker.cpp

@@ -2154,6 +2154,8 @@ bool TypeChecker::visit(MemberAccess const& _memberAccess)
 					"Circular reference for contract code access."
 				);
 		}
+		else if (magicType->kind() == MagicType::Kind::MetaType && memberName == "name")
+			annotation.isPure = true;
 	}
 
 	return false;

libsolidity/analysis/ViewPureChecker.cpp

@@ -340,7 +340,8 @@ void ViewPureChecker::endVisit(MemberAccess const& _memberAccess)
 			{MagicType::Kind::Message, "data"},
 			{MagicType::Kind::Message, "sig"},
 			{MagicType::Kind::MetaType, "creationCode"},
-			{MagicType::Kind::MetaType, "runtimeCode"}
+			{MagicType::Kind::MetaType, "runtimeCode"},
+			{MagicType::Kind::MetaType, "name"},
 		};
 		set<MagicMember> static const payableMembers{
 			{MagicType::Kind::Message, "value"}

libsolidity/ast/Types.cpp

@@ -3490,8 +3490,9 @@ MemberList::MemberMap MagicType::nativeMembers(ContractDefinition const*) const
 		ContractDefinition const& contract = dynamic_cast<ContractType const&>(*m_typeArgument).contractDefinition();
 		if (contract.canBeDeployed())
 			return MemberList::MemberMap({
-				{"creationCode", std::make_shared<ArrayType>(DataLocation::Memory)},
-				{"runtimeCode", std::make_shared<ArrayType>(DataLocation::Memory)}
+				{"creationCode", make_shared<ArrayType>(DataLocation::Memory)},
+				{"runtimeCode", make_shared<ArrayType>(DataLocation::Memory)},
+				{"name", make_shared<ArrayType>(DataLocation::Memory, true)},
 			});
 		else
 			return {};

libsolidity/codegen/CompilerUtils.h

@@ -186,6 +186,11 @@ public:
 	/// Stack post:
 	void memoryCopy();
 
+	/// Stores the given string in memory.
+	/// Stack pre: mempos
+	/// Stack post:
+	void storeStringData(bytesConstRef _data);
+
 	/// Converts the combined and left-aligned (right-aligned if @a _rightAligned is true)
 	/// external function type <address><function identifier> into two stack slots:
 	/// address (right aligned), function identifier (right aligned)
@@ -285,11 +290,6 @@ private:
 	/// Address of the precompiled identity contract.
 	static unsigned const identityContractAddress;
 
-	/// Stores the given string in memory.
-	/// Stack pre: mempos
-	/// Stack post:
-	void storeStringData(bytesConstRef _data);
-
 	/// Appends code that cleans higher-order bits for integer types.
 	void cleanHigherOrderBits(IntegerType const& _typeOnStack);
 

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1361,6 +1361,18 @@ bool ExpressionCompiler::visit(MemberAccess const& _memberAccess)
 			);
 			m_context << Instruction::POP;
 		}
+		else if (member == "name")
+		{
+			TypePointer arg = dynamic_cast<MagicType const&>(*_memberAccess.expression().annotation().type).typeArgument();
+			ContractDefinition const& contract = dynamic_cast<ContractType const&>(*arg).contractDefinition();
+			m_context << u256(contract.name().length() + 32);
+			utils().allocateMemory();
+			// store string length
+			m_context << u256(contract.name().length()) << Instruction::DUP2 << Instruction::MSTORE;
+			// adjust pointer
+			m_context << Instruction::DUP1 << u256(32) << Instruction::ADD;
+			utils().storeStringData(contract.name());
+		}
 		else
 			solAssert(false, "Unknown magic member.");
 		break;

test/libsolidity/SolidityEndToEndTest.cpp

@@ -15113,6 +15113,55 @@ BOOST_AUTO_TEST_CASE(code_access_content)
 	ABI_CHECK(callContractFunction("testCreation()"), encodeArgs(true));
 }
 
+BOOST_AUTO_TEST_CASE(contract_name)
+{
+	char const* sourceCode = R"(
+		contract C {
+			string public nameAccessor = type(C).name;
+			string public constant constantNameAccessor = type(C).name;
+
+			function name() public pure returns (string memory) {
+				return type(C).name;
+			}
+		}
+		contract D is C {
+			function name() public pure returns (string memory) {
+				return type(D).name;
+			}
+			function name2() public pure returns (string memory) {
+				return type(C).name;
+			}
+		}
+		contract ThisIsAVeryLongContractNameExceeding256bits {
+			string public nameAccessor = type(ThisIsAVeryLongContractNameExceeding256bits).name;
+			string public constant constantNameAccessor = type(ThisIsAVeryLongContractNameExceeding256bits).name;
+
+			function name() public pure returns (string memory) {
+				return type(ThisIsAVeryLongContractNameExceeding256bits).name;
+			}
+		}
+	)";
+
+	compileAndRun(sourceCode, 0, "C");
+	bytes argsC = encodeArgs(u256(0x20), u256(1), "C");
+	ABI_CHECK(callContractFunction("name()"), argsC);
+	ABI_CHECK(callContractFunction("nameAccessor()"), argsC);
+	ABI_CHECK(callContractFunction("constantNameAccessor()"), argsC);
+
+	compileAndRun(sourceCode, 0, "D");
+	bytes argsD = encodeArgs(u256(0x20), u256(1), "D");
+	ABI_CHECK(callContractFunction("name()"), argsD);
+	ABI_CHECK(callContractFunction("name2()"), argsC);
+
+	string longName = "ThisIsAVeryLongContractNameExceeding256bits";
+	compileAndRun(sourceCode, 0, longName);
+	bytes argsLong = encodeArgs(u256(0x20), u256(longName.length()), longName);
+	ABI_CHECK(callContractFunction("name()"), argsLong);
+	ABI_CHECK(callContractFunction("nameAccessor()"), argsLong);
+	ABI_CHECK(callContractFunction("constantNameAccessor()"), argsLong);
+}
+
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/syntaxTests/metaTypes/name.sol

@@ -0,0 +1,5 @@
+contract Test {
+    function f() public pure returns (string memory) {
+        return type(Test).name;
+    }
+}

test/libsolidity/syntaxTests/metaTypes/name_constant.sol

@@ -0,0 +1,4 @@
+contract C {
+  string public constant name = type(C).name;
+}
+// ----

test/libsolidity/syntaxTests/metaTypes/name_other_contract.sol

@@ -0,0 +1,10 @@
+contract Test {
+    function f() public pure returns (string memory) {
+        return type(C).name;
+    }
+}
+
+contract C {
+    function f() pure public {
+    }
+}