Files
clang-p2996/clang-tools-extra/docs/UseNullptrTransform.rst
Tareq A. Siraj c2aa348dd0 Allow users to specify NULL like macros to be replaced
-use-nullptr only replaced macro named NULL and ignored any user defined
macros that behaved like NULL. This patch introduces -user-null-macros
command line option to let users specify their custom NULL like macros.

- Added a -user-null-macros command line option that takes a
  comma-separated list of user-defined macros to be replaced when using
  the -use-nullptr transform.
- Added documentation.
- Updated testcase to reflect current behavior.
- Whitespace fixes.

Reviewers: revane, klimek, gribozavr
llvm-svn: 178243
2013-03-28 16:06:59 +00:00

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1.4 KiB
ReStructuredText

.. index:: Use-Nullptr Transform
=====================
Use-Nullptr Transform
=====================
The Use-Nullptr Transform is a transformation to convert the usage of null
pointer constants (eg. ``NULL``, ``0``) to use the new C++11 ``nullptr``
keyword. The transform is enabled with the :option:`-use-nullptr` option of
:program:`cpp11-migrate`.
Example
=======
.. code-block:: c++
void assignment() {
char *a = NULL;
char *b = 0;
char c = 0;
}
int *ret_ptr() {
return 0;
}
transforms to:
.. code-block:: c++
void assignment() {
char *a = nullptr;
char *b = nullptr;
char c = 0;
}
int *ret_ptr() {
return nullptr;
}
User defined macros
===================
By default this transform will only replace the ``NULL`` macro and will skip any
user-defined macros that behaves like ``NULL``. The user can use the
:option:`-user-null-macros` option to specify a comma-separated list of macro
names that will be transformed along with ``NULL``.
Example
-------
.. code-block:: c++
#define MY_NULL (void*)0
void assignment() {
void *p = MY_NULL;
}
using the command-line
.. code-block:: bash
cpp11-migrate -use-nullptr -user-null-macros=MY_NULL foo.cpp
transforms to:
.. code-block:: c++
#define MY_NULL NULL
void assignment() {
int *p = nullptr;
}
Risk
====
:option:`-risk` has no effect in this transform.