From 0cb93a5f7b0a12d205d9acfc9ed342494c90ab1f Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 4 Jul 2017 18:28:24 +0200
Subject: [PATCH 1/3] Test for internal "variable already present" error.

---
 test/libsolidity/SolidityEndToEndTest.cpp | 27 +++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp
index a6c01283c..c9771fbde 100644
--- a/test/libsolidity/SolidityEndToEndTest.cpp
+++ b/test/libsolidity/SolidityEndToEndTest.cpp
@@ -9696,6 +9696,33 @@ BOOST_AUTO_TEST_CASE(keccak256_assembly)
 	BOOST_CHECK(callContractFunction("i()") == fromHex("0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470"));
 }
 
+BOOST_AUTO_TEST_CASE(multi_modifiers)
+{
+	// This triggered a bug in some version because the variable in the modifier was not
+	// unregistered correctly.
+	char const* sourceCode = R"(
+		contract C {
+			uint public x;
+			modifier m1 {
+				address a1 = msg.sender;
+				x++;
+				_;
+			}
+			function f1() m1() {
+				x += 7;
+			}
+			function f2() m1() {
+				x += 3;
+			}
+		}
+	)";
+	compileAndRun(sourceCode, 0, "C");
+	BOOST_CHECK(callContractFunction("f1()") == bytes());
+	BOOST_CHECK(callContractFunction("x()") == encodeArgs(u256(8)));
+	BOOST_CHECK(callContractFunction("f2()") == bytes());
+	BOOST_CHECK(callContractFunction("x()") == encodeArgs(u256(12)));
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

From d58e4390942c6347c75cb5d45b503711338e80eb Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 4 Jul 2017 18:28:44 +0200
Subject: [PATCH 2/3] Fix internal "variable already present" error.

---
 libsolidity/codegen/ContractCompiler.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index c358a5192..cad388dfd 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -928,7 +928,10 @@ void ContractCompiler::appendModifierOrFunctionCode()
 				);
 			}
 			for (VariableDeclaration const* localVariable: modifier.localVariables())
+			{
+				addedVariables.push_back(localVariable);
 				appendStackVariableInitialisation(*localVariable);
+			}
 
 			stackSurplus =
 				CompilerUtils::sizeOnStack(modifier.parameters()) +

From 2432808793ea737a28f9c75042730724f4d050e8 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 4 Jul 2017 18:58:11 +0200
Subject: [PATCH 3/3] Changelog entry.

---
 Changelog.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Changelog.md b/Changelog.md
index 7c0c86a51..b44159785 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,8 @@
 ### 0.4.13 (unreleased)
 
+Bugfixes:
+ * Code Generator: Correctly unregister modifier variables.
+
 ### 0.4.12 (2017-07-03)
 
 Features: