Arch linux clang doesn't find standard library headers

[joejoepie]

Describe the bug
With standard clang version 6.0.1 and gcc version 8.2.1 (delivers std lib on arch) there is an issue of clang complaining that he does not find following headers:

• string
• map
• cmath
• functional
• limits

When compiling self written programs these issues do not occur. I've tried to edit the CMakeLists.txt by adding the include_directories where these files reside. This works, but then multiple files complain about an undeclared identifier "strlen".
I suppose the issue resides in customizing parameters when executing clang.

The cmake generator line i use is provided in your build guide:
CC=/usr/bin/clang CXX=/usr/bin/clang++ \ cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=../debug/filament ../..

This happens on a standard clean install of arch linux with the newest version of clang and gcc.

[romainguy]

Thanks for the report. Do you have libc++-dev installed? We require the use of clang and of the clang STL. Based on the error you're describing it sounds like you don't have libc++dev. The README has more information on the prerequisites.

[joejoepie]

Let me inform you that Arch linux has no such package. Clang in arch uses the gcc standard library by default if i'm not mistaken.

[romainguy]

That may be but our code doesn't compile with GCC's standard library.

[joejoepie]

Ok then it's a personal problem of mine, and i'll try to fix it. Just consider this a headsup than that your project does not compile on arch linux out of the box.

[romainguy]

I definitely appreciate the heads up. I'll investigate a bit more and try to find the package name for arch Linux to update our readme.

[romainguy]

libc++ might be available under the name libcxx. AUR has a libc++ apparently.

[joejoepie]

Building it now, i'll get back to you with results. My mistake that i didn't check that out before creating an issue.

[romainguy]

No need to apologize, I know it would be a lot easier if it worked with any combination of gcc/clang/libstdc++/libc++ :)

[joejoepie]

Thank you my friend! It compiles now :) Sorry for wasting your time. I'm excited to explore your engine ;)

[romainguy]

Glad you were able to get it to compile, don't hesitate if you run into other issues!

[krzysztofsroga]

I also can't build it on Arch due to libc++ problem
I installed the libc++ package from AUR so in my /usr/lib/ directory I see files:

-rwxr-xr-x  1 root root       28 Aug 25 12:18 libc++.so
lrwxrwxrwx  1 root root       13 Aug 25 12:18 libc++.so.1 -> libc++.so.1.0
-rwxr-xr-x  1 root root   849936 Aug 25 12:18 libc++.so.1.0

I can run examples from Clion, but when I try to build release(no matter if it's via build.sh file or CMake/Ninja) then I get:

/usr/bin/ld: cannot find -lc++
clang-6.0: error: linker command failed with exit code 1 (use -v to see invocation)

[UberLambda]

Same as @wefhy, I have both libc++ and libc++abi installed from the AUR (on Manjaro) but ld still can't find -lc++.

[eduardobraun]

I have the same problem with Arch and the libc++ from AUR.

Building with ./build release says that ld cannot find -lc++.

But if I try ld -lc++ --verbose then ld finds libc++:

attempt to open /usr/x86_64-pc-linux-gnu/lib64/libc++.so failed
attempt to open /usr/x86_64-pc-linux-gnu/lib64/libc++.a failed
attempt to open /usr/lib/libc++.so succeeded
...

Maybe It's something to do with how ninja finds the libraries, I don't really know how ninja works. I think I'll try to build using a Docker image when I have the time.

[lasagnaphil]

I don't think Ninja is a problem here, because the same thing has happened to me when using make (using the -m option).

Right now, the Manjaro repository hosts a libc++ / libc++abi package, but it does not include static libs. To fix this, you need to clone the PKGBUILD from the manjaro package Git repo (https://gitlab.manjaro.org/packages/community/libcxx.git), add the option options=('staticlibs') for the functions package_libc++() and package_libc++abi() in the PKGBUILD, and install it manually using makepkg -si --nocheck.

However, even when the libc++ static libraries are detected, it seems like there are still some problems left. I get a lot of linker errors, such as:

(.text._ZNSt3__17promiseIvE28set_exception_at_thread_exitESt13exception_ptr+0x63): undefined reference to `__cxa_allocate_exception'
/usr/bin/ld: (.text._ZNSt3__17promiseIvE28set_exception_at_thread_exitESt13exception_ptr+0x7d): undefined reference to `__cxa_guard_acquire'
/usr/bin/ld: (.text._ZNSt3__17promiseIvE28set_exception_at_thread_exitESt13exception_ptr+0xc3): undefined reference to `__cxa_guard_release'
/usr/bin/ld: (.text._ZNSt3__17promiseIvE28set_exception_at_thread_exitESt13exception_ptr+0xed): undefined reference to `__cxa_throw'
/usr/bin/ld: (.text._ZNSt3__17promiseIvE28set_exception_at_thread_exitESt13exception_ptr+0xfd): undefined reference to `__cxa_free_exception'

I thought maybe there are some incompatibilities between my current system's clang and libc++. But then I've checked that the two are both version 7.0.1. I am still investigating this error...

[lasagnaphil]

Finally solved the problem!

To compile release builds in Arch Linux (or Manjaro), you need to also link libc++abi. You need to use the flag FILAMENT_REQUIRES_CXXABI=ON when running build.sh. (Reading the project's CMakeLists.txt file, this flag was originally intended for CI environments...)

EDIT: exactly the same solution as #16...

[romainguy]

Thanks for the report! Note that this workaround is mentioned in the README.md file.