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

Clang Frontend
1

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?

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.

2

Hi Simone,

Have you tried compiling with -save-temps and looking at the preprocessor output (.ii) ?

Csaba

3

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.

4

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).

Thanks.

Simone

5

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.