Merge pull request argotorg#3880 from ethereum/addressMemberDocAndWarn

Improve documentation and warning about accessing contract members in…

Author: chriseth

Changelog.md

@@ -18,6 +18,7 @@ Features:
  * Syntax Checker: Issue warning for empty structs (or error as experimental 0.5.0 feature).
  * Syntax Checker: Warn about modifiers on functions without implementation (this will turn into an error with version 0.5.0).
  * Syntax Tests: Add source locations to syntax test expectations.
+ * Type Checker: Improve documentation and warnings for accessing contract members inherited from ``address``.
  * General: Introduce new constructor syntax using the ``constructor`` keyword as experimental 0.5.0 feature.
  * Inheritance: Error when using empty parentheses for base class constructors that require arguments as experimental 0.5.0 feature.
  * Inheritance: Error when using no parentheses in modifier-style constructor calls as experimental 0.5.0 feature.

docs/types.rst

@@ -179,8 +179,8 @@ All three functions ``call``, ``delegatecall`` and ``callcode`` are very low-lev
 The ``.gas()`` option is available on all three methods, while the ``.value()`` option is not supported for ``delegatecall``.
 
 .. note::
-    All contracts inherit the members of address, so it is possible to query the balance of the
-    current contract using ``this.balance``.
+    All contracts can be converted to ``address`` type, so it is possible to query the balance of the
+    current contract using ``address(this).balance``.
 
 .. note::
     The use of ``callcode`` is discouraged and will be removed in the future.

libsolidity/analysis/TypeChecker.cpp

@@ -1988,7 +1988,8 @@ bool TypeChecker::visit(MemberAccess const& _memberAccess)
 				m_errorReporter.warning(
 					_memberAccess.location(),
 					"Using contract member \"" + memberName +"\" inherited from the address type is deprecated." +
-					" Convert the contract to \"address\" type to access the member."
+					" Convert the contract to \"address\" type to access the member,"
+					" for example use \"address(contract)." + memberName + "\" instead."
 				);
 			}