[Python-checkins] devguide: Issue #27270: `parentheses-equality` warnings when building with clang and

Tue Jun 14 05:46:22 EDT 2016

https://hg.python.org/devguide/rev/18e960f930ab
changeset: 810:18e960f930ab
user: Xavier de Gaye <xdegaye at users.sourceforge.net>
date: Tue Jun 14 11:45:34 2016 +0200
summary:
 Issue #27270: `parentheses-equality` warnings when building with clang and ccache.
files:
 setup.rst | 7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/setup.rst b/setup.rst
--- a/setup.rst
+++ b/setup.rst
@@ -182,6 +182,7 @@
 root access is beyond the scope of this guide.
 
 .. _clang: http://clang.llvm.org/
+.. _ccache: https://ccache.samba.org/
 
 .. note:: While you need a C compiler to build CPython, you don't need any
 knowledge of the C language to contribute! Vast areas of CPython are
@@ -247,6 +248,12 @@
 ``-Wno-unused-value -Wno-empty-body -Qunused-arguments``. You can set your
 ``CFLAGS`` environment variable to these flags when running ``configure``.
 
+If you are using clang_ with ccache_, turn off the noisy
+``parentheses-equality`` warnings with the ``-Wno-parentheses-equality`` flag.
+These warnings are caused by clang not having enough information to detect
+that extraneous parentheses in expanded macros are valid, because the
+preprocessing is done separately by ccache.
+
 If you are using LLVM 2.8, also use the ``-no-integrated-as`` flag in order to
 build the :py:mod:`ctypes` module (without the flag the rest of CPython will
 still build properly).
-- 
Repository URL: https://hg.python.org/devguide
