Disallow explicit conversion of bytesXX to contract

Changelog.md

@@ -8,6 +8,7 @@ Features:
 Bugfixes:
  * Type Checker: Do not complain about new-style constructor and fallback function to have the same name.
  * Type Checker: Detect multiple constructor declarations in the new syntax and old syntax.
+ * Type Checker: Explicit conversion of ``bytesXX`` to ``contract`` is properly disallowed.
 
 ### 0.4.22 (2018-04-16)
 

libsolidity/ast/Types.cpp

@@ -1299,7 +1299,6 @@ bool FixedBytesType::isExplicitlyConvertibleTo(Type const& _convertTo) const
 {
 	return _convertTo.category() == Category::Integer ||
 		_convertTo.category() == Category::FixedPoint ||
-		_convertTo.category() == Category::Contract ||
 		_convertTo.category() == category();
 }
 

test/libsolidity/syntaxTests/types/bytes_to_contract.sol

@@ -0,0 +1,7 @@
+contract C {
+        function f() public pure {
+                C(bytes20(0x1234));
+        }
+}
+// ----
+// TypeError: (64-82): Explicit type conversion not allowed from "bytes20" to "contract C".