Do not try to display checksummed address for too-short/long address literals

libsolidity/analysis/TypeChecker.cpp

@@ -2000,8 +2000,8 @@ void TypeChecker::endVisit(Literal const& _literal)
 			m_errorReporter.warning(
 				_literal.location(),
 				"This looks like an address but has an invalid checksum. "
-				"If this is not used as an address, please prepend '00'. "
-				"Correct checksummed address: '" + _literal.getChecksummedAddress() + "'. "
+				"If this is not used as an address, please prepend '00'. " +
+				(!_literal.getChecksummedAddress().empty() ? "Correct checksummed address: '" + _literal.getChecksummedAddress() + "'. " : "") +
 				"For more information please see https://solidity.readthedocs.io/en/develop/types.html#address-literals"
 			);
 	}

libsolidity/ast/AST.cpp

@@ -587,5 +587,7 @@ bool Literal::passesAddressChecksum() const
 std::string Literal::getChecksummedAddress() const
 {
 	solAssert(isHexNumber(), "Expected hex number");
+	if (value().length != 42)
+		return string();
 	return dev::getChecksummedAddress(value());
 }

libsolidity/ast/AST.h

@@ -1613,7 +1613,7 @@ public:
 	bool looksLikeAddress() const;
 	/// @returns true if it passes the address checksum test.
 	bool passesAddressChecksum() const;
-	/// @returns the checksummed version of an address
+	/// @returns the checksummed version of an address (or empty string if not valid)
 	std::string getChecksummedAddress() const;
 
 private: