[cfe-dev] Can't compile C++ complex type number example after building Clang with non-standard gcc installation (AARCH64)

Mon Sep 7 17:48:39 PDT 2020

On Mon, 7 Sep 2020 at 17:18, Simone Atzeni <satzeni at nvidia.com> wrote:

> Thanks Csaba and Richard.
>
>
>
> I understand now, indeed if I add a “#define complex _Complex”, it
> compiles.
>
> I can’t understand why before adding the define, it worked with Clang 5
> and fails with Clang 8, though. Looks like this behavior changed after
> clang 5 (not sure about the exact version).
>

This probably means that your system didn't have a C++ <complex.h> that
Clang could find before, and so the C <complex.h> was picked up instead.

> Thanks.
>
> Simone
>
>
>
> *From:* Richard Smith <richard at metafoo.co.uk>
> *Sent:* Monday, September 7, 2020 4:21 PM
> *To:* Simone Atzeni <satzeni at nvidia.com>
> *Cc:* cfe-dev at lists.llvm.org
> *Subject:* Re: [cfe-dev] Can't compile C++ complex type number example
> after building Clang with non-standard gcc installation (AARCH64)
>
>
>
> *External email: Use caution opening links or attachments*
>
>
>
> On Mon, 7 Sep 2020, 14:27 Simone Atzeni via cfe-dev, <
> cfe-dev at lists.llvm.org> wrote:
>
> Hi,
>
>
>
> I built Clang using my own build of gcc-7.4.0.
>
>
>
> My cmake command looks like this:
>
>
>
> toolchain=/path/to/gcc-7.4.0/install
>
> CC=${toolchain}/bin/gcc
>
>
> CXX=${toolchain}/bin/g++
>
>
> cmake -G
> "Ninja"
>
> -DGCC_INSTALL_PREFIX=${toolchain}
>
>
> -DCMAKE_CXX_LINK_FLAGS="-Wl,-rpath,${toolchain}/lib64
> -L${toolchain}/lib64"
>
> -DTARGET_TRIPLE=aarch64-unknown-linux-gnu
>
>
> -DCMAKE_INSTALL_PREFIX="${install_dir}"
>
>
> -DCMAKE_BUILD_TYPE="Release"
>
>
> -DLLVM_ENABLE_PROJECTS="clang;compiler-rt"
>
>
> ${src}
>
>
>
> Then when I try to compile this example:
>
>
>
> $ cat complex.cpp
>
> #include <complex.h>
>
>
>
> int main()
>
> {
>
>     typedef float complex kmp_cmplx32;
>
> }
>
>
>
> I get the the error below.
>
> The include paths used by clang have `complex.h`, etc. The same example in
> “C” compiles fine.
>
> What am I missing?
>
> <complex.h> in C++ has nothing to do with <complex.h> in C, and in
> particular does not define a "complex" macro expanding to _Complex.
>
> Thanks!
>
> Simone
>
>
>
> $
> /home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/bin/clang++
> complex.cpp -v
>
> clang version 8.0.1
>
> Target: aarch64-unknown-linux-gnu
>
> Thread model: posix
>
> InstalledDir:
> /home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/bin
>
> Found candidate GCC installation:
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0
>
> Selected GCC installation:
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0
>
> Candidate multilib: .;@m64
>
> Selected multilib: .;@m64
>
> "/home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/bin/clang-8"
> -cc1 -triple aarch64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free
> -disable-llvm-verifier -discard-value-names -main-file-name complex.cpp
> -mrelocation-model static -mthread-model posix -mdisable-fp-elim
> -fmath-errno -masm-verbose -mconstructor-aliases -fuse-init-array
> -target-cpu generic -target-feature +neon -target-abi aapcs
> -fallow-half-arguments-and-returns -dwarf-column-info -debugger-tuning=gdb
> -v -resource-dir
> /home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/lib/clang/8.0.1
> -internal-isystem
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0
> -internal-isystem
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0/aarch64-unknown-linux-gnu
> -internal-isystem
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0/backward
> -internal-isystem /usr/local/include -internal-isystem
> /home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/lib/clang/8.0.1/include
> -internal-externc-isystem /usr/include/aarch64-linux-gnu
> -internal-externc-isystem /include -internal-externc-isystem /usr/include
> -fdeprecated-macro -fdebug-compilation-dir /home/satzeni -ferror-limit 19
> -fmessage-length 191 -fno-signed-char -fobjc-runtime=gcc -fcxx-exceptions
> -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o
> /tmp/complex-b60b10.o -x c++ complex.cpp -faddrsig
>
> clang -cc1 version 8.0.1 based upon LLVM 8.0.1 default target
> aarch64-unknown-linux-gnu
>
> ignoring nonexistent directory "/include"
>
> #include "..." search starts here:
>
> #include <...> search starts here:
>
>
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0
>
>
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0/aarch64-unknown-linux-gnu
>
>
> /home/sw/thirdparty/llvm-project/toolchains/install/Linux_aarch64/gcc-7.4.0/lib/gcc/aarch64-unknown-linux-gnu/7.4.0/../../../../include/c++/7.4.0/backward
>
> /usr/local/include
>
>
> /home/sw/thirdparty/llvm-project/install/Linux_aarch64/llvm-8.0/lib/clang/8.0.1/include
>
> /usr/include/aarch64-linux-gnu
>
> /usr/include
>
> End of search list.
>
> complex.cpp:5:26: error: expected ';' at end of declaration
>
>     typedef float complex kmp_cmplx32;
>
>                          ^
>
>                          ;
>
> 1 error generated.
>
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