[llvm-dev] Building LLVM with LLVM

[Fabiano Sidler via llvm-dev]

Hi folks!

I'm trying to build LLVM with LLVM on Ubuntu using the commands below.
Building it with the GNU stuff (cpp, gcc, g++ and binutils packages) works,
but after removing it, moving LLVM to /usr/local and symlinking /usr/bin/ld
to ld.lld, I'm getting the following:
=== snip ===
-- The C compiler identification is Clang 8.0.1
-- The CXX compiler identification is Clang 8.0.1
-- The ASM compiler identification is Clang
-- Found assembler: /usr/local/bin/clang
-- Check for working C compiler: /usr/local/bin/clang
-- Check for working C compiler: /usr/local/bin/clang -- broken
CMake Error at /usr/share/cmake-3.5/Modules/CMakeTestCCompiler.cmake:61 (message):
  The C compiler "/usr/local/bin/clang" is not able to compile a simple test
  program.

  It fails with the following output:

   Change Dir: /home/elux/build/CMakeFiles/CMakeTmp



  Run Build Command:"/usr/bin/make" "cmTC_a9eab/fast"

  /usr/bin/make -f CMakeFiles/cmTC_a9eab.dir/build.make
  CMakeFiles/cmTC_a9eab.dir/build

  make[1]: Entering directory '/home/elux/build/CMakeFiles/CMakeTmp'

  Building C object CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o

  /usr/local/bin/clang -o CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o -c
  /home/elux/build/CMakeFiles/CMakeTmp/testCCompiler.c

  Linking C executable cmTC_a9eab

  /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_a9eab.dir/link.txt
  --verbose=1

  /usr/local/bin/clang CMakeFiles/cmTC_a9eab.dir/testCCompiler.c.o -o
  cmTC_a9eab

  ld: error: cannot open crt1.o: No such file or directory

  ld: error: cannot open crti.o: No such file or directory

  ld: error: cannot open crtbegin.o: No such file or directory

  ld: error: unable to find library -lgcc

  ld: error: unable to find library -lgcc_s

  ld: error: unable to find library -lc

  ld: error: unable to find library -lgcc

  ld: error: unable to find library -lgcc_s

  ld: error: cannot open crtend.o: No such file or directory

  ld: error: cannot open crtn.o: No such file or directory

  clang-8: error: linker command failed with exit code 1 (use -v to see
  invocation)

  CMakeFiles/cmTC_a9eab.dir/build.make:97: recipe for target 'cmTC_a9eab'
  failed

  make[1]: *** [cmTC_a9eab] Error 1

  make[1]: Leaving directory '/home/elux/build/CMakeFiles/CMakeTmp'

  Makefile:126: recipe for target 'cmTC_a9eab/fast' failed

  make: *** [cmTC_a9eab/fast] Error 2





  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt:39 (project)


-- Configuring incomplete, errors occurred!
See also "/home/elux/build/CMakeFiles/CMakeOutput.log".
See also "/home/elux/build/CMakeFiles/CMakeError.log".
=== snap ===

Commands used:
=== snip ===
VERSION=8.0.1
DESTDIR=/tmp/llvm
PREFIX=/usr/local

#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/llvm-${VERSION}.src.tar.xz
#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/cfe-${VERSION}.src.tar.xz
#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/libcxx-${VERSION}.src.tar.xz
#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/libcxxabi-${VERSION}.src.tar.xz
#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/lld-${VERSION}.src.tar.xz
#wget https://github.com/llvm/llvm-project/releases/download/llvmorg-${VERSION}/compiler-rt-${VERSION}.src.tar.xz
tar xf llvm-${VERSION}.src.tar.xz
tar xf cfe-${VERSION}.src.tar.xz
tar xf libcxx-${VERSION}.src.tar.xz
tar xf libcxxabi-${VERSION}.src.tar.xz
tar xf lld-${VERSION}.src.tar.xz
tar xf compiler-rt-${VERSION}.src.tar.xz
mv cfe-${VERSION}.src         llvm-${VERSION}.src/projects/clang
mv libcxx-${VERSION}.src      llvm-${VERSION}.src/projects/libcxx
mv libcxxabi-${VERSION}.src   llvm-${VERSION}.src/projects/libcxxabi
mv lld-${VERSION}.src         llvm-${VERSION}.src/projects/lld
mv compiler-rt-${VERSION}.src llvm-${VERSION}.src/projects/compiler-rt
mkdir build
cd build
cmake \
  -DLLVM_ENABLE_FFI=ON \
  -DCMAKE_BUILD_TYPE=Release \
  -DLLVM_ENABLE_RTTI=ON \
  -DLLVM_TARGETS_TO_BUILD="host" \
  -DBUILD_SHARED_LIBS=ON \
  ../llvm-${VERSION}.src
cmake --build .
cmake -DCMAKE_INSTALL_PREFIX=${DESTDIR}${PREFIX} -P cmake_install.cmake
=== snap ===

Any hints?

Greetings,
Fabiano