Tests and changelog for <address>.code.length shortcut

test/libsolidity/semanticTests/various/code_length.sol

@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-3.0
+contract C {
+    uint len1;
+    uint len2;
+    constructor() {
+        uint mem_ptr_before;
+        uint mem_ptr_after;
+
+        assembly {
+            mem_ptr_before := mload(64)
+        }
+
+        len1 = address(0).code.length;
+
+        assembly {
+            mem_ptr_after := mload(64)
+        }
+
+        // To check that no memory was allocated and written.
+        assert(mem_ptr_before == mem_ptr_after);
+
+        len2 = address(this).code.length;
+
+        // To check that no memory was allocated and written.
+        assembly {
+            mem_ptr_after := mload(64)
+        }
+
+        assert(mem_ptr_before == mem_ptr_after);
+
+    }
+
+    function f() public view returns (bool r1, bool r2) {
+        uint mem_ptr_before;
+        uint mem_ptr_after;
+
+        assembly {
+            mem_ptr_before := mload(64)
+        }
+
+        r1 = address(this).code.length > 50;
+
+        assembly {
+            mem_ptr_after := mload(64)
+        }
+
+        // To check that no memory was allocated and written.
+        assert(mem_ptr_before == mem_ptr_after);
+
+        address a = address(0);
+        r2 = a.code.length == 0;
+
+        // To check that no memory was allocated and written.
+        assembly {
+            mem_ptr_after := mload(64)
+        }
+
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// constructor()
+// f(): true, true -> true, true

test/libsolidity/semanticTests/various/code_length_contract_member.sol

@@ -0,0 +1,17 @@
+// Test to see if type.code.length does extcodesize(type) only when type is an address.
+struct S {
+    bytes32 code;
+    bytes32 another;
+}
+
+contract C {
+    S s;
+
+    function f() public returns (uint, uint, bool) {
+        return (s.code.length, s.another.length, address(this).code.length > 50);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> 0x20, 0x20, true