Document that libc++-dev is a build dependency

[SimonSapin]

In DioxusLabs/taffy#450 at first I didn’t manage to compile yoga-rs. Output line that seems most relevant:

  src/yoga/yoga/Yoga.h:371:10: fatal error: 'functional' file not found

Full output:

   Compiling yoga v0.4.0
error: failed to run custom build command for `yoga v0.4.0`

Caused by:
  process didn't exit successfully: `/home/simon/projects/taffy/target/debug/build/yoga-96bccafd4f3c4b8f/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-changed=src/yoga/yoga
  TARGET = Some("x86_64-unknown-linux-gnu")
  OPT_LEVEL = Some("0")
  HOST = Some("x86_64-unknown-linux-gnu")
  cargo:rerun-if-env-changed=CXX_x86_64-unknown-linux-gnu
  CXX_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=CXX_x86_64_unknown_linux_gnu
  CXX_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_CXX
  HOST_CXX = None
  cargo:rerun-if-env-changed=CXX
  CXX = None
  cargo:rerun-if-env-changed=CXXFLAGS_x86_64-unknown-linux-gnu
  CXXFLAGS_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=CXXFLAGS_x86_64_unknown_linux_gnu
  CXXFLAGS_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_CXXFLAGS
  HOST_CXXFLAGS = None
  cargo:rerun-if-env-changed=CXXFLAGS
  CXXFLAGS = None
  cargo:rerun-if-env-changed=CRATE_CC_NO_DEFAULTS
  CRATE_CC_NO_DEFAULTS = None
  DEBUG = Some("true")
  CARGO_CFG_TARGET_FEATURE = Some("fxsr,sse,sse2")
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/event/event.o" "-c" "src/yoga/yoga/event/event.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/internal/experiments.o" "-c" "src/yoga/yoga/internal/experiments.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/log.o" "-c" "src/yoga/yoga/log.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/Utils.o" "-c" "src/yoga/yoga/Utils.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGConfig.o" "-c" "src/yoga/yoga/YGConfig.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGEnums.o" "-c" "src/yoga/yoga/YGEnums.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGLayout.o" "-c" "src/yoga/yoga/YGLayout.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGNode.o" "-c" "src/yoga/yoga/YGNode.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGNodePrint.o" "-c" "src/yoga/yoga/YGNodePrint.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGStyle.o" "-c" "src/yoga/yoga/YGStyle.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGValue.o" "-c" "src/yoga/yoga/YGValue.cpp"
  exit status: 0
  running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-4" "-fno-omit-frame-pointer" "-m64" "-I" "src/yoga" "-Wall" "-Wextra" "-std=c++11" "-fno-omit-frame-pointer" "-fexceptions" "-Wall" "-O3" "-fPIC" "-o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/Yoga.o" "-c" "src/yoga/yoga/Yoga.cpp"
  exit status: 0
  cargo:rerun-if-env-changed=AR_x86_64-unknown-linux-gnu
  AR_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=AR_x86_64_unknown_linux_gnu
  AR_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_AR
  HOST_AR = None
  cargo:rerun-if-env-changed=AR
  AR = None
  cargo:rerun-if-env-changed=ARFLAGS_x86_64-unknown-linux-gnu
  ARFLAGS_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=ARFLAGS_x86_64_unknown_linux_gnu
  ARFLAGS_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_ARFLAGS
  HOST_ARFLAGS = None
  cargo:rerun-if-env-changed=ARFLAGS
  ARFLAGS = None
  running: ZERO_AR_DATE="1" "ar" "cq" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/libyoga.a" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/event/event.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/internal/experiments.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/log.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/Utils.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGConfig.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGEnums.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGLayout.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGNode.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGNodePrint.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGStyle.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/YGValue.o" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/src/yoga/yoga/Yoga.o"
  exit status: 0
  running: "ar" "s" "/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out/libyoga.a"
  exit status: 0
  cargo:rustc-link-lib=static=yoga
  cargo:rustc-link-search=native=/home/simon/projects/taffy/target/debug/build/yoga-261b21c272a3ad54/out
  cargo:rerun-if-env-changed=CXXSTDLIB_x86_64-unknown-linux-gnu
  CXXSTDLIB_x86_64-unknown-linux-gnu = None
  cargo:rerun-if-env-changed=CXXSTDLIB_x86_64_unknown_linux_gnu
  CXXSTDLIB_x86_64_unknown_linux_gnu = None
  cargo:rerun-if-env-changed=HOST_CXXSTDLIB
  HOST_CXXSTDLIB = None
  cargo:rerun-if-env-changed=CXXSTDLIB
  CXXSTDLIB = None
  cargo:rustc-link-lib=stdc++

  --- stderr
  fatal: not a git repository (or any of the parent directories): .git
  fatal: not a git repository (or any of the parent directories): .git
  src/yoga/yoga/Yoga.h:371:10: fatal error: 'functional' file not found
  thread 'main' panicked at 'Unable to generate bindings: ClangDiagnostic("src/yoga/yoga/Yoga.h:371:10: fatal error: 'functional' file not found\n")', /home/simon/tmp/cargo-home/registry/src/github.com-1ecc6299db9ec823/yoga-0.4.0/build.rs:65:10
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

It’s only with external help that I eventually found I needed to install LLVM’s libc++. I already had /usr/include/c++/12.2.1/functional on my system but that one came with GCC.

Please consider adding something in README.md to document this requirement.

[nicoburns]

The ideal fix for this would be to drop the dependency on libc++ ( in favour of libstdc++), because the libc++ dep is also blocking docs.rs builds of yoga-rs. See:

• libunwind-14-dev breaks libunwind on Linux rust-lang/crates-build-env#125
• Add libc++-dev package to linux environment rust-lang/crates-build-env#121

And fixing that on the docs.rs side is blocked by this ubuntu bug https://bugs.launchpad.net/ubuntu/+source/llvm-toolchain-14/+bug/1989124.

However, we currently can't do that due to this bindgen bug rust-lang/rust-bindgen#2157, so in the meantime documenting the dependency is probably sensible.

[bschwind]

Thanks for bringing this up, I updated the README for now to reflect this.