Implemented events with function type as one of its indexed parameters

test/libsolidity/syntaxTests/events/event_function_type_indexed.sol

@@ -0,0 +1,6 @@
+contract C {
+	event Test(function() external indexed);
+	function f() public {
+		emit Test(this.f);
+	}
+}

test/libsolidity/syntaxTests/events/event_library_function.sol

@@ -0,0 +1,35 @@
+library L {
+	function f() public {
+		int x = 1;
+	}
+}
+
+contract C {
+	event Test(function() external indexed);
+
+	function g() public {
+		Test(L.f);
+	}
+}
+
+contract D {
+	event Test(function() external);
+
+	function f() public {
+		Test(L.f);
+	}
+}
+
+contract E {
+	event Test(function() external indexed);
+
+	using L for D;
+
+	function k() public {
+		Test(D.f);
+	}
+}
+// ----
+// TypeError 9553: (140-143): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested.
+// TypeError 9553: (230-233): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested.
+// TypeError 9553: (345-348): Invalid type for argument in function call. Invalid implicit conversion from function D.f() to function () external requested.