Merge pull request #5775 from ethereum/codeAccess

Provide access to code of contract types.

3 files changed, 36 insertions, 1 deletions

diff --git a/docs/miscellaneous.rst b/docs/miscellaneous.rst
index 5a6f3875..69124c77 100644
--- a/docs/miscellaneous.rst
+++ b/docs/miscellaneous.rst
@@ -385,6 +385,8 @@ Global Variables
 - ``<address>.balance`` (``uint256``): balance of the :ref:`address` in Wei
 - ``<address payable>.send(uint256 amount) returns (bool)``: send given amount of Wei to :ref:`address`, returns ``false`` on failure
 - ``<address payable>.transfer(uint256 amount)``: send given amount of Wei to :ref:`address`, throws on failure
+- ``type(C).creationCode`` (``bytes memory``): creation bytecode of the given contract, see :ref:`Type Information<meta-type>`.
+- ``type(C).runtimeCode`` (``bytes memory``): runtime bytecode of the given contract, see :ref:`Type Information<meta-type>`.
 
 .. note::
     Do not rely on ``block.timestamp``, ``now`` and ``blockhash`` as a source of randomness,
@@ -445,7 +447,7 @@ These keywords are reserved in Solidity. They might become part of the syntax in
 ``abstract``, ``after``, ``alias``, ``apply``, ``auto``, ``case``, ``catch``, ``copyof``, ``default``,
 ``define``, ``final``, ``immutable``, ``implements``, ``in``, ``inline``, ``let``, ``macro``, ``match``,
 ``mutable``, ``null``, ``of``, ``override``, ``partial``, ``promise``, ``reference``, ``relocatable``,
-``sealed``, ``sizeof``, ``static``, ``supports``, ``switch``, ``try``, ``type``, ``typedef``, ``typeof``,
+``sealed``, ``sizeof``, ``static``, ``supports``, ``switch``, ``try``, ``typedef``, ``typeof``,
 ``unchecked``.
 
 Language Grammar
diff --git a/docs/types/value-types.rst b/docs/types/value-types.rst
index 077587dd..09db1423 100644
--- a/docs/types/value-types.rst
+++ b/docs/types/value-types.rst
@@ -329,6 +329,9 @@ Contracts do not support any operators.
 The members of contract types are the external functions of the contract
 including public state variables.
 
+For a contract ``C`` you can use ``type(C)`` to access
+:ref:`type information<meta-type>` about the contract.
+
 .. index:: byte array, bytes32
 
 Fixed-size byte arrays
diff --git a/docs/units-and-global-variables.rst b/docs/units-and-global-variables.rst
index c47f257b..ce7706c1 100644
--- a/docs/units-and-global-variables.rst
+++ b/docs/units-and-global-variables.rst
@@ -244,3 +244,33 @@ Furthermore, all functions of the current contract are callable directly includi
 .. note::
     Prior to version 0.5.0, there was a function called ``suicide`` with the same
     semantics as ``selfdestruct``.
+
+.. index:: type, creationCode, runtimeCode
+
+.. _meta-type:
+
+Type Information
+----------------
+
+The expression ``type(X)`` can be used to retrieve information about the
+type ``X``. Currently, there is limited support for this feature, but
+it might be expanded in the future. The following properties are
+available for a conract type ``C``:
+
+``type(C).creationCode``:
+    Memory byte array that contains the creation bytecode of the contract.
+    This can be used in inline assembly to build custom creation routines,
+    especially by using the ``create2`` opcode.
+    This property can **not** be accessed in the contract itself or any
+    derived contract. It causes the bytecode to be included in the bytecode
+    of the call site and thus circular references like that are not possible.
+
+``type(C).runtimeCode``:
+    Memory byte array that contains the runtime bytecode of the contract.
+    This is the code that is usually deployed by the constructor of ``C``.
+    If ``C`` has a constructor that uses inline assembly, this might be
+    different from the actually deployed bytecode. Also note that libraries
+    modify their runtime bytecode at time of deployment to guard against
+    regular calls.
+    The same restrictions as with ``.creationCode`` also apply for this
+    property.