[SMTChecker] Fixing conversion from StringLiteral to FixedBytes

test/libsolidity/smtCheckerTests/operators/bitwise_and_fixed_bytes.sol

@@ -1,7 +1,11 @@
 pragma experimental SMTChecker;
 contract C {
-  function f() public pure returns (byte) {
-    return (byte("") & (""));
-  }
+	function f() public pure {
+		assert(byte("") & ("") == byte(0)); // should hold
+		assert(byte(0xAA) & byte(0x55) == byte(0)); // should hold
+		assert(byte(0xFF) & byte(0xAA) == byte(0xAA)); // should hold
+		assert(byte(0xFF) & byte(0xAA) == byte(0)); // should fail
+	}
 }
 // ----
+// Warning 6328: (253-295): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/operators/bitwise_not_fixed_bytes.sol

@@ -9,4 +9,4 @@ contract C {
 	}
 }
 // ----
-// Warning 6328: (175-198): CHC: Assertion violation happens here.
+// Warning 6328: (133-156): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/operators/bitwise_or_fixed_bytes.sol

@@ -1,7 +1,11 @@
 pragma experimental SMTChecker;
 contract C {
-  function f() public pure returns (byte) {
-    return (byte(0x0F) | (byte(0xF0)));
-  }
+	function f() public pure returns (byte) {
+		byte b = (byte(0x0F) | (byte(0xF0)));
+		assert(b == byte(0xFF)); // should hold
+		assert(b == byte(0x00)); // should fail
+		return b;
+	}
 }
 // ----
+// Warning 6328: (172-195): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/operators/bitwise_xor_fixed_bytes.sol

@@ -1,8 +1,11 @@
 pragma experimental SMTChecker;
 contract Simp {
-    function f3() public pure returns (byte) {
-        bytes memory y = "def";
-        return y[0] ^ "e";
-    }
+	function f3() public pure returns (byte) {
+		bytes memory y = "def";
+		assert(y[0] ^ "e" != byte(0)); // should hold
+		assert(y[1] ^ "e" != byte(0)); // should fail
+		return y[0];
+	}
 }
 // ----
+// Warning 6328: (168-197): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/typecast/string_literal_to_dynamic_bytes.sol

@@ -0,0 +1,12 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f() public pure {
+		bytes memory b = bytes(hex"ffff");
+		assert(b.length == 2); // should hold
+		assert(b[0] == byte(uint8(255))); // should hold
+		assert(b[1] == byte(uint8(100))); // should fail
+	}
+}
+// ----
+// Warning 6328: (204-236): CHC: Assertion violation happens here.

test/libsolidity/smtCheckerTests/typecast/string_literal_to_fixed_bytes_upcast.sol

@@ -0,0 +1,10 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function f() public pure {
+		assert(bytes4(hex"0000ffff") == bytes4(hex"ffff")); // should fail
+		assert(bytes4(hex"ffff0000") == bytes4(hex"ffff")); // should hold
+	}
+}
+// ----
+// Warning 6328: (76-126): CHC: Assertion violation happens here.