@Axel I also noticed another two warnings about redefined Vc macros (for all three C++11, C++14 and C++17 builds):
(...)
[ 72%] Built target Imt
[ 72%] Generating G__MathCore.cxx, ../../lib/MathCore.pcm
While building module 'MathCore':
While building module 'Vc' imported from /.../v6-24-00-patches/include/Math/Types.h:19:
In file included from <module-includes>:1:
In file included from /usr/include/Vc/Vc:30:
In file included from /usr/include/Vc/vector.h:37:
In file included from /usr/include/Vc/sse/vector.h:402:
In file included from /usr/include/Vc/scalar/../common/../sse/vector.tcc:30:
/usr/include/Vc/scalar/../common/../sse/../common/bitscanintrinsics.h:37:13: warning: '_bit_scan_forward' macro redefined [-Wmacro-redefined]
# define _bit_scan_forward(x) __builtin_ctz(x)
^
/.../v6-24-00-patches/etc//cling/lib/clang/9.0.1/include/ia32intrin.h:72:9: note: previous definition is here
#define _bit_scan_forward(A) __bsfd((A))
^
While building module 'MathCore':
While building module 'Vc' imported from /.../v6-24-00-patches/include/Math/Types.h:19:
In file included from <module-includes>:1:
In file included from /usr/include/Vc/Vc:30:
In file included from /usr/include/Vc/vector.h:37:
In file included from /usr/include/Vc/sse/vector.h:402:
In file included from /usr/include/Vc/scalar/../common/../sse/vector.tcc:30:
/usr/include/Vc/scalar/../common/../sse/../common/bitscanintrinsics.h:44:13: warning: '_bit_scan_reverse' macro redefined [-Wmacro-redefined]
# define _bit_scan_reverse(x) _Vc_bit_scan_reverse_asm(x)
^
/.../v6-24-00-patches/etc//cling/lib/clang/9.0.1/include/ia32intrin.h:73:9: note: previous definition is here
#define _bit_scan_reverse(A) __bsrd((A))
^
Scanning dependencies of target G__MathCore
[ 72%] Building CXX object math/mathcore/CMakeFiles/G__MathCore.dir/G__MathCore.cxx.o
[ 72%] Built target G__MathCore
Scanning dependencies of target MathCore
(...)