Test cases for bindng operators to builtin functions

test/libsolidity/syntaxTests/operators/custom/bind_encode_function.sol

@@ -0,0 +1,10 @@
+type Int is int16;
+
+using {abi.encode as +} for Int;
+
+function f(Int, Int) pure returns (Int) {
+    return Int.wrap(0);
+}
+
+// ----
+// DeclarationError 7920: (27-37): Identifier not found or not unique.

test/libsolidity/syntaxTests/operators/custom/bind_event.sol

@@ -0,0 +1,8 @@
+type Int is int16;
+
+using {IntError as +} for Int;
+
+error IntError(Int a, Int b);
+
+// ----
+// TypeError 8187: (27-35): Expected function name.

test/libsolidity/syntaxTests/operators/custom/bind_keccak_function.sol

@@ -0,0 +1,6 @@
+type Int is int16;
+
+using {keccak256 as +} for Int;
+
+// ----
+// TypeError 8187: (27-36): Expected function name.

test/libsolidity/syntaxTests/operators/custom/bind_revert_function.sol

@@ -0,0 +1,6 @@
+type Int is int16;
+
+using {revert as +} for Int;
+
+// ----
+// DeclarationError 7920: (27-33): Identifier not found or not unique.