From 2df60bec923e1bac74cde00ae9bda641ca29d6c1 Mon Sep 17 00:00:00 2001
From: chriseth <c@ethdev.com>
Date: Mon, 5 Dec 2016 18:40:50 +0100
Subject: Type after shift should be type of left operand.

---
 libsolidity/ast/Types.cpp                 | 47 +++++++++++++++++++++++++++----
 test/libsolidity/SolidityEndToEndTest.cpp | 15 ++++++++++
 2 files changed, 57 insertions(+), 5 deletions(-)

diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index 6b4dd432..896d51fa 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -340,6 +340,28 @@ TypePointer IntegerType::binaryOperatorResult(Token::Value _operator, TypePointe
 		_other->category() != category()
 	)
 		return TypePointer();
+	if (Token::isShiftOp(_operator))
+	{
+		// Disable >>> here.
+		if (_operator == Token::SHR)
+			return TypePointer();
+
+		// Shifts are not symmetric with respect to the type
+		if (isAddress())
+			return TypePointer();
+		if (IntegerType const* otherInt = dynamic_cast<decltype(otherInt)>(_other.get()))
+		{
+			if (!otherInt->isAddress())
+				return shared_from_this();
+		}
+		else if (RationalNumberType const* otherRat = dynamic_cast<decltype(otherRat)>(_other.get()))
+		{
+			if (!otherRat->isFractional())
+				return shared_from_this();
+		}
+		return TypePointer();
+	}
+
 	auto commonType = Type::commonType(shared_from_this(), _other); //might be a integer or fixed point
 	if (!commonType)
 		return TypePointer();
@@ -347,11 +369,6 @@ TypePointer IntegerType::binaryOperatorResult(Token::Value _operator, TypePointe
 	// All integer types can be compared
 	if (Token::isCompareOp(_operator))
 		return commonType;
-	// Disable >>> here.
-	if (_operator == Token::SHR)
-		return TypePointer();
-	if (Token::isShiftOp(_operator) && !isAddress()) // && !_other->isAddress())
-		return shared_from_this();
 	if (Token::isBooleanOp(_operator))
 		return TypePointer();
 	if (auto intType = dynamic_pointer_cast<IntegerType const>(commonType))
@@ -959,6 +976,26 @@ TypePointer FixedBytesType::unaryOperatorResult(Token::Value _operator) const
 
 TypePointer FixedBytesType::binaryOperatorResult(Token::Value _operator, TypePointer const& _other) const
 {
+	if (Token::isShiftOp(_operator))
+	{
+		// Disable >>> here.
+		if (_operator == Token::SHR)
+			return TypePointer();
+
+		// Shifts are not symmetric with respect to the type
+		if (IntegerType const* otherInt = dynamic_cast<decltype(otherInt)>(_other.get()))
+		{
+			if (!otherInt->isAddress())
+				return shared_from_this();
+		}
+		else if (RationalNumberType const* otherRat = dynamic_cast<decltype(otherRat)>(_other.get()))
+		{
+			if (!otherRat->isFractional())
+				return shared_from_this();
+		}
+		return TypePointer();
+	}
+
 	auto commonType = dynamic_pointer_cast<FixedBytesType const>(Type::commonType(shared_from_this(), _other));
 	if (!commonType)
 		return TypePointer();
diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp
index 837caa2d..0ac88a81 100644
--- a/test/libsolidity/SolidityEndToEndTest.cpp
+++ b/test/libsolidity/SolidityEndToEndTest.cpp
@@ -8505,6 +8505,21 @@ BOOST_AUTO_TEST_CASE(shift_left_uint8)
 	BOOST_CHECK(callContractFunction("f(uint8,uint8)", u256(0x66), u256(8)) == encodeArgs(u256(0)));
 }
 
+BOOST_AUTO_TEST_CASE(shift_left_larger_type)
+{
+	char const* sourceCode = R"(
+		contract C {
+			function f() returns (int8) {
+				uint8 x = 255;
+				int8 y = 1;
+				return a << b;
+			}
+		}
+	)";
+	compileAndRun(sourceCode, 0, "C");
+	BOOST_CHECK(callContractFunction("f()") == encodeArgs(u256(1) << 255));
+}
+
 BOOST_AUTO_TEST_CASE(shift_left_assignment)
 {
 	char const* sourceCode = R"(
-- 
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