Support address().codehash

test/libsolidity/semanticTests/various/codehash.sol

@@ -0,0 +1,21 @@
+contract C {
+    function f() public returns (bytes32) {
+        // non-existent in tests
+        return address(0).codehash;
+    }
+    function g() public returns (bytes32) {
+        // precompile
+        return address(0x1).codehash;
+    }
+    function h() public returns (bool) {
+        return address(this).codehash != 0;
+    }
+}
+
+// ====
+// EVMVersion: >=constantinople
+// compileViaYul: also
+// ----
+// f() -> 0x0
+// g() -> 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470
+// h() -> true

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

@@ -0,0 +1,8 @@
+contract C {
+    function f() public view returns (bytes32) {
+        return address(this).codehash;
+    }
+}
+// ====
+// EVMVersion: >=constantinople
+// ----

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

@@ -0,0 +1,9 @@
+contract C {
+    function f() public view returns (bytes32) {
+        return address(this).codehash;
+    }
+}
+// ====
+// EVMVersion: <constantinople
+// ----
+// TypeError 7598: (77-99): "codehash" is not supported by the VM version.

test/libsolidity/syntaxTests/viewPureChecker/address_constantinople.sol

@@ -0,0 +1,11 @@
+contract C {
+    function f() public view returns (bytes32) {
+        return address(this).codehash;
+    }
+    function g() public view returns (bytes32) {
+        return address(0).codehash;
+    }
+}
+// ====
+// EVMVersion: >=constantinople
+// ----