ldWrapper tries to call non-existent binary when cross compiling

[expipiplus1]

In an environment with clang.override {binutils = binutils.override{cross.target = "arm-none-eabi";} clang-wrapper/bin/ld tries to call binutils-arm-none-eabi/bin/ld when the file is actually located at binutils-arm-none-eabi/bin/arm-none-eabi-ld.

I'm not entirely sure that I'm going about this the right way, please let me know if there's a better way to cross compile with clang.

To reproduce:

default.nix

with import <nixpkgs> { };

let
  crossSystem = {
    config = "arm-none-eabi";
  };
  binutils-cross = (binutils.override {cross = crossSystem;});
in

stdenv.mkDerivation rec {
  name = "bug";
  version = "0.0.1";

  buildInputs = [
    (clang.override {binutils = binutils-cross;})
    binutils-cross
    ];
}

main.c

int main(){}

Run

nix-shell --pure
clang main.c -target arm-none-eabi -march=armv6

Output:

/nix/store/4kgv92cb4p1q6lpf1q4cvhkk507n2253-clang-wrapper-3.6.2/bin/ld: line 166: /nix/store/6p37d9411wd09yba0ffw0qwxcbvgk0yx-binutils-2.23.1-arm-none-eabi/bin/ld: No such file or directory
clang-3.6: error: linker command failed with exit code 1 (use -v to see invocation)

[expipiplus1]

I'm not convinced I'm doing things correctly, as cc-wrapper is still injecting references to glibc to the clang arguments.

[expipiplus1]

This is the erroneous line https://github.com/NixOS/nixpkgs/blob/master/pkgs/build-support/cc-wrapper/default.nix#L160

It seems as though gcc has https://github.com/NixOS/nixpkgs/tree/master/pkgs/build-support/gcc-cross-wrapper but there's nothing similar for clang.

[garbas]

i'm pinging ppl who i think might have some knowledge about cross-compiling: @viric @bjornfor

[bjornfor]

Sorry, I have no useful input. (I don't use Nix for cross-compilation, but I want to.)

[dvc94ch]

Here's an example clang cross toolchain I built:

with import ../../../nixpkgs {};

let
  pkgsCross = import ../../../nixpkgs {
    inherit system;
    crossSystem = rec {
      config = "armv7-unknown-linux-musleabihf";
      arch = "arm";
      libc = "musl";
      gcc = {
        arch = "armv7-a";
        fpu = "neon";
        float = "hard";
      };
    };
  };

  libgcc = system.pkgsCross.libgcc.crossDrv;

  clang = callPackage ../../../nixpkgs/pkgs/build-support/cc-wrapper {
    cc = llvmPackages.clang-unwrapped;
    isClang = true;
    stdenv = llvmPackages.stdenv;
    libc = pkgsCross.muslCross;
    extraPackages = [ libgcc libcxx libcxxabi ];
    nativeTools = false;
    nativeLibc = false;
    binutils = pkgsCross.binutilsCross;
  };
  libcxxStdenv = overrideCC stdenv clang;
in

libcxxStdenv.mkDerivation rec {
  name = "bug";
  version = "0.0.1";

  src = ./.;

  CFLAGS = "-B${libgcc}/lib -target armv7-unknown-linux-musl-eabihf";

  phases = ["unpackPhase" "buildPhase" "installPhase"];

  installPhase = ''
    mkdir -p $out/bin
    cp hello $out/bin
  '';
}

You'll also need #16217, #15867, gcc6, this binutils patch (clang is surprisingly unflexible in specifying the linker to use, this commit hasn't landed yet llvm-mirror/clang@635bc7f) and my libgcc hack

diff --git a/pkgs/development/tools/misc/binutils/default.nix b/pkgs/development/tools/misc/binutils/default.nix
index 80b5643..b969ab4 100644
--- a/pkgs/development/tools/misc/binutils/default.nix
+++ b/pkgs/development/tools/misc/binutils/default.nix
@@ -75,7 +75,11 @@ stdenv.mkDerivation rec {

   enableParallelBuilding = true;

-  postFixup = optionalString (cross == null) "ln -s $out/bin $dev/bin"; # tools needed for development
+  postFixup =
+    if cross == null then
+      "ln -s $out/bin $dev/bin" # tools needed for development
+    else
+      "ln -s $out/bin/${cross.config}-ld $out/bin/ld";

   meta = with stdenv.lib; {
     description = "Tools for manipulating binaries (linker, assembler, etc.)";

{ stdenv, gcc, glibc, cross ? null, gccCrossStageFinal ? null }:

let
  arch = "x86_64-unknown-linux-gnu";

  path =
    if cross == null
    then "${gcc.cc}/lib/gcc/${arch}/${gcc.cc.version}"
    else "${gccCrossStageFinal.gcc}/lib/gcc/${cross.config}/${gccCrossStageFinal.gcc.version}";

  path-libgcc_s =
    if cross == null
    then "${glibc.out}"
    else "${gccCrossStageFinal.gcc}/${cross.config}";
in

stdenv.mkDerivation rec {
  name = "libgcc";

  buildCommand = ''
    mkdir -p "$out/lib"

    cp ${path}/libgcc.a $out/lib
    cp ${path}/crtbegin.o $out/lib
    cp ${path}/crtbeginS.o $out/lib
    cp ${path}/crtbeginT.o $out/lib
    cp ${path}/crtendS.o $out/lib
    cp ${path}/crtend.o $out/lib
    cp ${path}/crtfastmath.o $out/lib
    cp ${path}/libgcc_eh.a $out/lib

    cp ${path-libgcc_s}/lib/libgcc_s.so $out/lib/libgcc_s.so
    cp ${path-libgcc_s}/lib/libgcc_s.so.1 $out/lib/libgcc_s.so.1
  '';
}

[copumpkin]

@dvc94ch did you look at what we do on darwin to use clang/llvm systemwide? I think we have quite a bit of badly conditioned logic in individual derivations that asks for stdenv.isDarwin when it really should be stdenv.isLLVM but that should be a fairly easy fix.

[Ericson2314]

#25232 should have fixed this #25047 will fix the wrapper scripts

[Ericson2314]

Actually #26007 fixed this