Adding syntax tests for bytes.concat.

test/libsolidity/syntaxTests/array/concat/bytes_concat_empty_invalid.sol

@@ -0,0 +1,7 @@
+contract C {
+    function g() public pure returns (bytes memory) {
+        return bytes.concat;
+    }
+}
+// ----
+// TypeError 6359: (82-94): Return argument type function () pure returns (bytes memory) is not implicitly convertible to expected type (type of first return variable) bytes memory.

test/libsolidity/syntaxTests/array/concat/bytes_concat_on_type_info.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public {
+        bytes memory a;
+        bytes memory b = type(bytes).concat(a);
+    }
+}
+// ----
+// TypeError 4259: (93-98): Invalid type for argument in the function call. A contract type or an integer type is required, but type(bytes) provided.

test/libsolidity/syntaxTests/array/concat/bytes_concat_on_variable.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f() public {
+        bytes memory a;
+        bytes memory b = a.concat();
+    }
+}
+// ----
+// TypeError 9582: (88-96): Member "concat" not found or not visible after argument-dependent lookup in bytes memory.

test/libsolidity/syntaxTests/array/concat/bytes_concat_wrong_type.sol

@@ -0,0 +1,14 @@
+contract C {
+    bytes s;
+    function f(bytes calldata c, string calldata c1) public {
+        bytes memory a;
+        bytes16 b;
+        uint8[] memory num;
+        bytes1[] memory m;
+        bytes memory d = bytes.concat(a, b, c, num, s, "abc", m, c1, bytes(c1));
+    }
+}
+// ----
+// TypeError 8015: (233-236): Invalid type for argument in the bytes.concat function call. bytes or fixed bytes type is required, but uint8[] provided.
+// TypeError 8015: (248-249): Invalid type for argument in the bytes.concat function call. bytes or fixed bytes type is required, but bytes1[] provided.
+// TypeError 8015: (251-253): Invalid type for argument in the bytes.concat function call. bytes or fixed bytes type is required, but string provided.