C: Difference between revisions

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name = "env";

}

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== Use a clang compiled from source ==

Unwrapped compilers usually do not any libraries/headers in nix. This is an issue if you work on the clang code base.

Assuming you have build llvm/clang like this

$ git clone https://github.com/llvm/llvm-project

$ cd llvm-project

$ nix-shell -p cmake --command "mkdir build && cd build && cmake -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" -DCMAKE_INSTALL_PREFIX=../install -DCMAKE_BUILD_TYPE=Debug ../llvm && make -j$(nproc)"

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You can create a wrapper around your local build binaries like this:

# This file assumes that your llvm binaries are stored in ./build/bin

# impure-clang.nix

{ stdenv, wrapCC, runtimeShell }:

wrapCC (stdenv.mkDerivation {

name = "impure-clang";

dontUnpack = true;

installPhase = ''

mkdir -p $out/bin

for bin in ${toString (builtins.attrNames (builtins.readDir ./build/bin))}; do

cat > $out/bin/$bin <<EOF

#!${runtimeShell}

exec "${toString ./.}/build/bin/$bin" "\$@"

EOF

chmod +x $out/bin/$bin

done

'';

passthru.isClang = true;

})

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Than you can create a <code>shell.nix</code> like this:

with import <nixpkgs>;

pkgs.mkShell {

nativeBuildInputs = [

cmake

(callPackage ./impure-clang.nix)

];

}

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And use your self-compiled clang in a nix-shell:

$ nix-shell --command 'clang --version'

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