From c81c3c3daff4a96980da2fce2d80a9e57f9db953 Mon Sep 17 00:00:00 2001
From: Tom McLaughlin <tom@codedown.io>
Date: Thu, 19 Nov 2020 12:29:02 -0700
Subject: [PATCH] cling: init at 0.7.0 (#64319)

Co-authored-by: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
---
 .../interpreters/cling/default.nix            | 102 ++++++++++++++++++
 pkgs/top-level/all-packages.nix               |   2 +
 2 files changed, 104 insertions(+)
 create mode 100644 pkgs/development/interpreters/cling/default.nix

diff --git a/pkgs/development/interpreters/cling/default.nix b/pkgs/development/interpreters/cling/default.nix
new file mode 100644
index 00000000000..68819fa7ab0
--- /dev/null
+++ b/pkgs/development/interpreters/cling/default.nix
@@ -0,0 +1,102 @@
+{ stdenv
+, python
+, libffi
+, git
+, cmake
+, zlib
+, fetchgit
+, makeWrapper
+, runCommand
+, runCommandNoCC
+, llvmPackages_5
+, glibc
+}:
+
+let
+  unwrapped = stdenv.mkDerivation rec {
+    pname = "cling-unwrapped";
+    version = "0.7";
+
+    src = fetchgit {
+      url = "http://root.cern/git/clang.git";
+      # This commit has the tag cling-0.7 so we use it, even though cpt.py
+      # tries to use refs/tags/cling-patches-rrelease_50
+      rev = "354b25b5d915ff3b1946479ad07f3f2768ea1621";
+      branchName = "cling-patches";
+      sha256 = "0q8q2nnvjx3v59ng0q3qqqhzmzf4pmfqqiy3rz1f3drx5w3lgyjg";
+    };
+
+    clingSrc = fetchgit {
+      url = "http://root.cern/git/cling.git";
+      rev = "70163975eee5a76b45a1ca4016bfafebc9b57e07";
+      sha256 = "1mv2fhk857kp5rq714bq49iv7gy9fgdwibydj5wy1kq2m3sf3ysi";
+    };
+
+    preConfigure = ''
+      echo "add_llvm_external_project(cling)" >> tools/CMakeLists.txt
+      cp -r $clingSrc ./tools/cling
+      chmod -R a+w ./tools/cling
+    '';
+
+    nativeBuildInputs = [ python git cmake ];
+    buildInputs = [ libffi llvmPackages_5.llvm zlib ];
+
+    cmakeFlags = [
+      "-DLLVM_TARGETS_TO_BUILD=host;NVPTX"
+      "-DLLVM_ENABLE_RTTI=ON"
+
+      # Setting -DCLING_INCLUDE_TESTS=ON causes the cling/tools targets to be built;
+      # see cling/tools/CMakeLists.txt
+      "-DCLING_INCLUDE_TESTS=ON"
+    ];
+
+    meta = with stdenv.lib; {
+      description = "The Interactive C++ Interpreter";
+      homepage = "https://root.cern/cling/";
+      license = with licenses; [ lgpl21 ncsa ];
+      maintainers = with maintainers; [ thomasjm ];
+      platforms = platforms.unix;
+    };
+  };
+
+  # The flags passed to the wrapped cling should
+  # a) prevent it from searching for system include files and libs, and
+  # b) provide it with the include files and libs it needs (C and C++ standard library)
+
+  # These are also exposed as cling.flags/cling.compilerIncludeFlags because it's handy to be
+  # able to pass them to tools that wrap Cling, particularly Jupyter kernels such as xeus-cling
+  # and the built-in jupyter-cling-kernel. Both of these use Cling as a library by linking against
+  # libclingJupyter.so, so the makeWrapper approach to wrapping the binary doesn't work.
+  # Thus, if you're packaging a Jupyter kernel, you either need to pass these flags as extra
+  # args to xcpp (for xeus-cling) or put them in the environment variable CLING_OPTS
+  # (for jupyter-cling-kernel)
+  flags = [
+    "-nostdinc"
+    "-nostdinc++"
+    "-isystem" "${glibc.dev}/include"
+    "-I" "${unwrapped}/include"
+    "-I" "${unwrapped}/lib/clang/5.0.2/include"
+  ];
+
+  # Autodetect the include paths for the compiler used to build Cling, in the same way Cling does at
+  # https://github.com/root-project/cling/blob/v0.7/lib/Interpreter/CIFactory.cpp#L107:L111
+  # Note: it would be nice to just put the compiler in Cling's PATH and let it do this by itself, but
+  # unfortunately passing -nostdinc/-nostdinc++ disables Cling's autodetection logic.
+  compilerIncludeFlags = runCommandNoCC "compiler-include-flags.txt" {} ''
+    export LC_ALL=C
+    ${stdenv.cc}/bin/c++ -xc++ -E -v /dev/null 2>&1 | sed -n -e '/^.include/,''${' -e '/^ \/.*++/p' -e '}' > tmp
+    sed -e 's/^/-isystem /' -i tmp
+    tr '\n' ' ' < tmp > $out
+  '';
+
+in
+
+runCommand "cling-${unwrapped.version}" {
+  buildInputs = [ makeWrapper ];
+  inherit unwrapped flags compilerIncludeFlags;
+  inherit (unwrapped) meta;
+} ''
+  makeWrapper $unwrapped/bin/cling $out/bin/cling \
+    --add-flags "$(cat "$compilerIncludeFlags")" \
+    --add-flags "$flags"
+''
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 8c96a8b961a..0d9893de7fe 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -10190,6 +10190,8 @@ in
 
   ceptre = callPackage ../development/interpreters/ceptre { };
 
+  cling = callPackage ../development/interpreters/cling { };
+
   clips = callPackage ../development/interpreters/clips { };
 
   clisp = callPackage ../development/interpreters/clisp { };