Make non-payable default for conversion to address.

test/libsolidity/syntaxTests/functionTypes/external_function_type_to_address_payable.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f() public view returns (address payable) {
+        return address(this.f);
+    }
+}
+// ----
+// TypeError: (85-100): Return argument type address is not implicitly convertible to expected type (type of first return variable) address payable.

test/libsolidity/syntaxTests/types/address/address_to_payable_address_double.sol

@@ -0,0 +1,7 @@
+contract C {
+    function f(address a) public pure returns (address payable) {
+        return address(address(a));
+    }
+}
+// ----
+// TypeError: (94-113): Return argument type address is not implicitly convertible to expected type (type of first return variable) address payable.

test/libsolidity/syntaxTests/types/address/bytes_long_to_payable_address.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f(bytes32 x) public pure returns (address payable) {
+        return address(x);
+    }
+}
+// ----
+// TypeError: (94-104): Explicit type conversion not allowed from "bytes32" to "address".
+// TypeError: (94-104): Return argument type address is not implicitly convertible to expected type (type of first return variable) address payable.

test/libsolidity/syntaxTests/types/address/bytes_short_to_payable_address.sol

@@ -0,0 +1,8 @@
+contract C {
+    function f(bytes10 x) public pure returns (address payable) {
+        return address(x);
+    }
+}
+// ----
+// TypeError: (94-104): Explicit type conversion not allowed from "bytes10" to "address".
+// TypeError: (94-104): Return argument type address is not implicitly convertible to expected type (type of first return variable) address payable.

test/libsolidity/syntaxTests/types/address/bytes_to_payable_address.sol

@@ -0,0 +1,5 @@
+contract C {
+    function f(bytes20 x) public pure returns (address payable) {
+        return address(x);
+    }
+}

test/libsolidity/syntaxTests/types/address/uint_to_payable_address.sol

@@ -0,0 +1,5 @@
+contract C {
+    function f(uint x) public pure returns (address payable) {
+        return address(x);
+    }
+}