gcc11Stdenv and clang

[sternenseemann]

@cmm

I mean libstdc++ , yes. I do want it it and not LLVM’s libcxx , but I want a version that is newer than 10, and I thought that deriving my env from gcc11Stdenv would get me there. And it does if I compile with gcc11 , but not if I compile with llvmPackages_latest.clang .

Right! Then I misunderstood you. How this works is a bit non-obvious, actually. I think it’s relatively difficult to build gcc and libstdc++ separately, so we need to get it from gcc (at the moment). For clang, the cc-wrapper takes care of injecting this into the flags passed to clang, for this it receives an argument called gccForLibs (if you want to follow the code in pkgs/build-support/cc-wrapper/default.nix). We can of course override this:

overrideCC llvmPackages.stdenv (
  llvmPackages.clang.override {
    gccForLibs = gcc11.cc; # the cc attribute is the *un*wrapped compiler we require
  }
)