Hi,
At FNAL, we build the XRootD client for binary distribution and use by
several experiments with our ecosystem which usually involves a specific
compiler which is different to that native to the system. We are
currently refreshing our software stack to support clang 5.0.0 at C++17
on Linux (and MacOS, but that's not the point of this query).
We are building XRootD 2.7.0 on (e.g. SL7), configured as follows:
CC=clang \
CXX=clang++ \
CXXFLAGS='-fno-omit-frame-pointer -std=c++17' \
CFLAGS=-fno-omit-frame-pointer \
cmake /home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0 \
-DCMAKE_BUILD_TYPE=RelWithDebInfo \
-DPYTHON_LIBRARY=/home/greenc/work/cet-is/test-products/python/v2_7_14/Linux64bit+3.10-2.17/lib/python2.7 \
-DPYTHON_INCLUDE_DIR=/home/greenc/work/cet-is/test-products/python/v2_7_14/Linux64bit+3.10-2.17/include/python2.7 \
-DCMAKE_INSTALL_PREFIX=/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/Linux64bit+3.10-2.17-c1-prof \
-DENABLE_LIBEVENT=FALSE
Unfortunately, CC and CXX do not appear to be propagated to the
compilation commands used to produce the library for the python
bindings, so I patched setup.py, viz:
diff -Naur xrootd-4.7.0/bindings/python/setup.py.in xrootd-4.7.0-new/bindings/python/setup.py.in
--- xrootd-4.7.0/bindings/python/setup.py.in 2017-08-25 09:16:16.000000000 -0500
+++ xrootd-4.7.0-new/bindings/python/setup.py.in 2017-09-19 08:49:59.271173898 -0500
@@ -16,7 +16,13 @@
py_cflags = cfg_vars["PY_CFLAGS"]
cfg_vars["PY_CFLAGS"] = " ".join( flag for flag in py_cflags.split() if flag not in ['-Wstrict-prototypes' ${CLANG_PROHIBITED} ] )
+ccl=cfg_vars["CC"].split()
+ccl[0]="${CMAKE_C_COMPILER}"
+cfg_vars["CC"] = " ".join(ccl)
+cxxl=cfg_vars["CXX"].split()
+cxxl[0]="${CMAKE_CXX_COMPILER}"
+cfg_vars["CXX"] = " ".join(cxxl)
+cfg_vars["PY_CXXFLAGS"] = "${CMAKE_CXX_FLAGS}"
sources = list()
depends = list()
This appears to get the compiler series correct, but based on verbose
log entries, C++ source code files appear to be being compiled with the
C compiler executable, viz:
/home/greenc/work/cet-is/test-products/clang/v5_0_0/Linux64bit+3.10-2.17/bin/clang \
-pthread -fno-strict-aliasing -g -O2 -DNDEBUG -g -fwrapv -O3 -Wall -fPIC \
-I/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/src \
-I/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/build/Linux64bit+3.10-2.17-c1-prof/src \
-I/home/greenc/work/cet-is/test-products/python/v2_7_14/Linux64bit+3.10-2.17/include/python2.7 \
-c /home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDFile.cc \
-o build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDFile.o -g
although clang++ is invoked as expected for the final link step:
/home/greenc/work/cet-is/test-products/clang/v5_0_0/Linux64bit+3.10-2.17/bin/clang++ \
-pthread -shared \
-L/home/greenc/work/cet-is/test-products/sqlite/v3_20_01_00/Linux64bit+3.10-2.17/lib \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDFile.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDModule.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDCopyProcess.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDCopyProgressHandler.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDFileSystem.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/Utils.o \
build/temp.linux-x86_64-2.7/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/source/xrootd-4.7.0/bindings/python/src/PyXRootDURL.o \
-L/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/build/Linux64bit+3.10-2.17-c1-prof/src \
-L/home/greenc/work/cet-is/test-products/xrootd/v4_7_0/build/Linux64bit+3.10-2.17-c1-prof/src/XrdCl \
-L/home/greenc/work/cet-is/test-products/python/v2_7_14/Linux64bit+3.10-2.17/lib \
-lXrdCl -lXrdUtils -ldl -lpython2.7 -o \
build/lib.linux-x86_64-2.7/pyxrootd/client.so \
I am somewhat ignorant of compiling extensions for Python bindings, but
PY_CXXFLAGS is obviously not being passed to the compilation of the C++
code because the C front end is apparently being invoked instead. I've
even tried renaming the .cc files to .cpp just in case setuptools is
confused by the .cc file extension, but no joy there either.
By way of further information, this is with Python 2.7.14 and setuptools
36.5.0.
Is there someone out there to tell me what I should be doing to get what
I need (or perhaps, to tell me authoritatively that I don't need it
after all)?
Thanks for any help,
Chris Green.
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