Error: libstdc++ version must be at least

Beginners
1

I compiled clang version 16.0.0.
Next I want build libcxx. I can’t build with gcc because i error : sizeof whatever ==0. Next I try build with clang, was error : no new i delete operator, I add stdc++ to utils/TableGen

But next:
I can’t build with clang because is cmake error:

CMake Error at cmake/modules/CheckCompilerVersion.cmake:88 (message):
  libstdc++ version must be at least 7.1.
Call Stack (most recent call first):
  cmake/config-ix.cmake:15 (include)
  CMakeLists.txt:848 (include)

for sources with tag llvmorg-16.0.0 and
libstdc++ version must be at least 7.1.
for sources with tag llvmorg-15.0.0
even -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=True nothing helps

2

Note: If I change clang to clang++ is OK, (at least OK for generating makefile or ninja)
Whats is difference between clang an clang++, this is the same file other named, or clang only for .c, clang++ for c++, or another difference?

3

Please post the full cmake command that you are using.

4

cmake -DCMAKE_CXX_COMPILER=clang-16 -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" -DCMAKE_BUILD_TYPE=Release -G Ninja ../llvm -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=True

before, I build clang 16 from sources with tag llvmorg-16.0.0 from Quick Start:
Building LLVM with CMake — LLVM 17.0.0git documentation, build was successfull

$ clang-16 --version
clang version 16.0.0 (https://github.com/llvm/llvm-project.git 08d094a0e457360ad8b94b017d2dc277e697ca76)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
5

clang is the C compiler. clang++ is the C++ compiler. This needs to be clang++-16 as you have already discovered.