Equality operator allowed for external function types

test/libsolidity/syntaxTests/functionTypes/comparison_operator_for_external_functions_with_extra_gas_slots.sol

@@ -0,0 +1,12 @@
+contract C {
+    function external_test_function() external {}
+    function comparison_operator_for_external_function_with_extra_slots() external returns (bool) {
+        return (
+            (this.external_test_function{gas: 4} == this.external_test_function) &&
+            (this.external_test_function{gas: 4} == this.external_test_function{gas: 4})
+        );
+    }
+}
+// ----
+// TypeError 2271: (193-259): Operator == not compatible with types function () external and function () external
+// TypeError 2271: (277-351): Operator == not compatible with types function () external and function () external

test/libsolidity/syntaxTests/functionTypes/comparison_operators_between_internal_and_external_function_pointers.sol

@@ -0,0 +1,23 @@
+contract C {
+    function external_test_function() external {}
+    function internal_test_function() internal {}
+
+    function comparison_operator_between_internal_and_external_function_pointers() external returns (bool) {
+        function () external external_function_pointer_local = this.external_test_function;
+        function () internal internal_function_pointer_local = internal_test_function;
+
+        assert(
+            this.external_test_function == external_function_pointer_local &&
+            internal_function_pointer_local == internal_test_function
+        );
+        assert(
+            internal_function_pointer_local != external_function_pointer_local &&
+            internal_test_function != this.external_test_function
+        );
+
+        return true;
+    }
+}
+// ----
+// TypeError 2271: (606-672): Operator != not compatible with types function () and function () external
+// TypeError 2271: (688-741): Operator != not compatible with types function () and function () external

test/libsolidity/syntaxTests/functionTypes/comparison_operators_external_functions_with_different_parameters.sol

@@ -0,0 +1,26 @@
+contract C {
+    function external_test_function1(uint num) external {}
+    function external_test_function2(bool val) external {}
+
+    function comparison_operator_between_internal_and_external_function_pointers() external returns (bool) {
+        function () external external_function_pointer_local1 = this.external_test_function1;
+        function () external external_function_pointer_local2 = this.external_test_function2;
+
+        assert(
+            this.external_test_function1 == external_function_pointer_local1 &&
+            this.external_test_function2 == external_function_pointer_local2
+        );
+        assert(
+            external_function_pointer_local2 != external_function_pointer_local1 &&
+            this.external_test_function2 != this.external_test_function1
+        );
+
+        return true;
+    }
+}
+// ----
+// TypeError 9574: (249-333): Type function (uint256) external is not implicitly convertible to expected type function () external.
+// TypeError 9574: (343-427): Type function (bool) external is not implicitly convertible to expected type function () external.
+// TypeError 2271: (458-522): Operator == not compatible with types function (uint256) external and function () external
+// TypeError 2271: (538-602): Operator == not compatible with types function (bool) external and function () external
+// TypeError 2271: (726-786): Operator != not compatible with types function (bool) external and function (uint256) external