stdenv.cc: add proper C++ support

overlay/default.nix

@@ -79,6 +79,11 @@ in nullPkgs // {
     # keep libposix NEEDED
   }) coreutils);
 
+  gccForLibs = if targetPlatform.isGenode then
+    final.genodePackages.genodeSources.toolchain.cc
+  else
+    prev.gccForLibs;
+
   gdb = addPatchesTarget [ ./gdb/genode.patch ] gdb;
 
   genodeLibcCross = callPackage ./libc { };
@@ -93,10 +98,6 @@ in nullPkgs // {
   else
     prev.grub2;
 
-  libconfig =
-    overrideAttrsHost (attrs: { configureFlags = [ "--disable-examples" ]; })
-    libconfig;
-
   libcCrossChooser = name:
     if stdenv.targetPlatform.isGenode then
       targetPackages.genodeLibcCross

overlay/libcxx/default.nix

@@ -0,0 +1,16 @@
+{ genodePackages, symlinkJoin }:
+let inherit (genodePackages) genodeSources;
+in symlinkJoin {
+  name = "libcxx";
+  paths = with genodePackages; [ stdcxx ];
+  postBuild = ''
+    local headerDir="''${!outputDev}/include"
+    mkdir -p "$headerDir"
+    pushd ${genodeSources.ports.stdcxx}/*
+    cp -r \
+      include/include/stdcxx/* \
+      ${genodeSources}/repos/libports/include/stdcxx \
+      "$headerDir"
+    popd
+  '';
+}

overlay/llvm-11/default.nix

@@ -96,12 +96,25 @@ let
     lldClang = if stdenv.targetPlatform.isGenode then
       wrapCCWith rec {
         cc = tools.clang-unwrapped;
+        gccForLibs = genodePackages.genodeSources.toolchain.cc;
         bintools = wrapBintoolsWith { inherit (tools) bintools; };
         extraBuildCommands = with genodePackages.genodeSources; ''
           echo "--gcc-toolchain=${toolchain.cc}" >> $out/nix-support/cc-cflags
           echo "--sysroot=${genodeBase}" >> $out/nix-support/cc-cflags
           echo "-I${genodeBase}/include" >> $out/nix-support/cc-cflags
           echo "-L ${genodeBase}" >> $out/nix-support/cc-cflags
+
+          for dir in ${gccForLibs}/${stdenv.targetPlatform.config}/include/c++/*; do
+            echo "-isystem $dir" >> $out/nix-support/libcxx-cxxflags
+          done
+          echo "-isystem ${genodePackages.genodeSources}/repos/libports/include/stdcxx" >> $out/nix-support/libcxx-cxxflags
+          for dir in ${genodePackages.genodeSources.ports.stdcxx}/*/include/stdcxx; do
+            echo "-isystem $dir" >> $out/nix-support/libcxx-cxxflags
+            echo "-isystem $dir/std" >> $out/nix-support/libcxx-cxxflags
+            echo "-isystem $dir/c_global" >> $out/nix-support/libcxx-cxxflags
+          done
+
+          echo "${genodePackages.stdcxx}/lib/stdcxx.lib.so" >> $out/nix-support/libcxx-ldflags
         '';
       }
     else

packages/genodelabs/toolchain.nix

@@ -62,8 +62,15 @@ let
         makeWrapper ''${BIN} x86_64-unknown-genode-''${BIN#$out/bin/genode-x86-}
       done
       popd
+      ln -s $out/aarch64-none-elf $out/aarch64-unknown-genode
+      ln -s $out/arm-none-eabi $out/arm-unknown-genode
+      ln -s $out/riscv64-unknown-elf $out/riscv-unknown-genode
+      ln -s $out/x86_64-pc-elf $out/x86_64-unknown-genode
     '';
   } // {
+    # Needed by the GCC wrapper.
+    langC = true;
+    langCC = true;
     isGNU = true;
     targetPrefix = {
       aarch64-genode = "genode-arm-";