Introduce address(...).code

test/libsolidity/semanticTests/various/address_code.sol

@@ -0,0 +1,22 @@
+contract C {
+    bytes public initCode;
+
+    constructor() {
+        // This should catch problems, but lets also test the case the optimiser is buggy.
+        assert(address(this).code.length == 0);
+        initCode = address(this).code;
+    }
+
+    // To avoid dependency on exact length.
+    function f() public view returns (bool) { return address(this).code.length > 400; }
+    function g() public view returns (uint) { return address(0).code.length; }
+    function h() public view returns (uint) { return address(1).code.length; }
+}
+// ====
+// compileViaYul: false
+// ----
+// constructor() ->
+// initCode() -> 0x20, 0
+// f() -> true
+// g() -> 0
+// h() -> 0

test/libsolidity/semanticTests/various/address_code_complex.sol

@@ -0,0 +1,19 @@
+contract A {
+    constructor() {
+        assembly {
+            // This is only 7 bytes here.
+            mstore(0, 0x48aa5566000000)
+            return(0, 32)
+        }
+    }
+}
+
+contract C {
+    function f() public returns (bytes memory) { return address(new A()).code; }
+    function g() public returns (uint) { return address(new A()).code.length; }
+}
+// ====
+// compileViaYul: false
+// ----
+// f() -> 0x20, 0x20, 0x48aa5566000000
+// g() -> 0x20