Merge pull request #2758 from ethereum/warnShift

Warn about shift of literals.

3 files changed, 42 insertions, 2 deletions

diff --git a/Changelog.md b/Changelog.md
index 9bc0b354..7d026862 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -7,6 +7,7 @@ Features:
  * Static Analyzer: Warn about large storage structures.
  * Metadata: Store experimental flag in metadata CBOR.
  * Type Checker: More detailed error message for invalid overrides.
+ * Type Checker: Warn about shifting a literal.
 
 Bugfixes:
  * Parser: Enforce commas between array and tuple elements.
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index dbc95c4f..ca848dd0 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -1305,8 +1305,9 @@ void TypeChecker::endVisit(BinaryOperation const& _operation)
 		_operation.leftExpression().annotation().isPure &&
 		_operation.rightExpression().annotation().isPure;
 
-	if (_operation.getOperator() == Token::Exp)
+	if (_operation.getOperator() == Token::Exp || _operation.getOperator() == Token::SHL)
 	{
+		string operation = _operation.getOperator() == Token::Exp ? "exponentiation" : "shift";
 		if (
 			leftType->category() == Type::Category::RationalNumber &&
 			rightType->category() != Type::Category::RationalNumber
@@ -1320,7 +1321,7 @@ void TypeChecker::endVisit(BinaryOperation const& _operation)
 			))
 				m_errorReporter.warning(
 					_operation.location(),
-					"Result of exponentiation has type " + commonType->toString() + " and thus "
+					"Result of " + operation + " has type " + commonType->toString() + " and thus "
 					"might overflow. Silence this warning by converting the literal to the "
 					"expected type."
 				);
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 51d60596..1c83e1a3 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -1765,6 +1765,44 @@ BOOST_AUTO_TEST_CASE(exp_warn_literal_base)
 	CHECK_SUCCESS(sourceCode);
 }
 
+BOOST_AUTO_TEST_CASE(shift_warn_literal_base)
+{
+	char const* sourceCode = R"(
+		contract test {
+			function f() returns(uint) {
+				uint8 x = 100;
+				return 10 << x;
+			}
+		}
+	)";
+	CHECK_WARNING(sourceCode, "might overflow");
+	sourceCode = R"(
+		contract test {
+			function f() returns(uint) {
+				uint8 x = 100;
+				return uint8(10) << x;
+			}
+		}
+	)";
+	CHECK_SUCCESS(sourceCode);
+	sourceCode = R"(
+		contract test {
+			function f() returns(uint) {
+				return 2 << 80;
+			}
+		}
+	)";
+	CHECK_SUCCESS(sourceCode);
+	sourceCode = R"(
+		contract test {
+			function f() returns(uint) {
+				 uint8 x = 100;
+				 return 10 >> x;
+			}
+		}
+	)";
+	CHECK_SUCCESS(sourceCode);
+}
 
 BOOST_AUTO_TEST_CASE(warn_var_from_zero)
 {