From 76ef802d3d60cc4d199f19ba69e8bcfe63b88e7b Mon Sep 17 00:00:00 2001
From: Bas van Dijk <v.dijk.bas@gmail.com>
Date: Sun, 23 Jun 2019 21:11:49 +0200
Subject: mkShell: compose shellHooks

Running the following expression with nix-shell:

  let
    pkgs = import <nixpkgs> {};

    shell1 = pkgs.mkShell {
      shellHook = ''
        echo shell1
      '';
    };

    shell2 = pkgs.mkShell {
      shellHook = ''
        echo shell2
      '';
    };

    shell3 = pkgs.mkShell {
      inputsFrom = [ shell1 shell2 ];
      shellHook = ''
        echo shell3
      '';
    };
  in shell3

Will now results in:
shell2
shell1
shell3

Note that packages in the front of inputsFrom have precedence over
packages in the back. The outermost mkShell has precedence over all.
---
 pkgs/build-support/mkshell/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'pkgs/build-support')

diff --git a/pkgs/build-support/mkshell/default.nix b/pkgs/build-support/mkshell/default.nix
index a98b4affacba..698974590880 100644
--- a/pkgs/build-support/mkshell/default.nix
+++ b/pkgs/build-support/mkshell/default.nix
@@ -25,6 +25,7 @@ let
     "nativeBuildInputs"
     "propagatedBuildInputs"
     "propagatedNativeBuildInputs"
+    "shellHook"
   ];
 in
 
@@ -37,6 +38,9 @@ stdenv.mkDerivation ({
   propagatedBuildInputs = mergeInputs "propagatedBuildInputs";
   propagatedNativeBuildInputs = mergeInputs "propagatedNativeBuildInputs";
 
+  shellHook = lib.concatStringsSep "\n" (lib.catAttrs "shellHook"
+    (lib.reverseList inputsFrom ++ [attrs]));
+
   nobuildPhase = ''
     echo
     echo "This derivation is not meant to be built, aborting";
-- 
cgit 1.4.1


From cee35739ff0800f5738ecbedb43c356a2f06c96f Mon Sep 17 00:00:00 2001
From: Bas van Dijk <v.dijk.bas@gmail.com>
Date: Sun, 23 Jun 2019 21:39:29 +0200
Subject: mkshell: improve mergeInputs

mergeInputs is now simply defined in terms of `concatLists` and
`catAttrs` instead of a more complicated `foldr`.

Note that the order of PATH has also changed. For example running the
following with nix-shell:

  let
    pkgs = import <nixpkgs> {};

    shell1 = pkgs.mkShell {
      buildInputs = [ pkgs.htop ];
    };

    shell2 = pkgs.mkShell {
      buildInputs = [ pkgs.hello ];
    };

    shell3 = pkgs.mkShell {
      inputsFrom = [ shell1 shell2 ];
      buildInputs = [ pkgs.tree ];
    };

  in shell3

Results in the following PATH:

$ echo $PATH
...
/nix/store/yifq4bikf7m07160bpia7z48ciqddbfi-tree-1.8.0/bin:
/nix/store/vhxqk81234ivqw1a7j200a1c69k8mywi-htop-2.2.0/bin:
/nix/store/n9vm3m58y1n3rg3mlll17wanc9hln58k-hello-2.10/bin
...

Previously the order was:

/nix/store/n9vm3m58y1n3rg3mlll17wanc9hln58k-hello-2.10/bin
/nix/store/vhxqk81234ivqw1a7j200a1c69k8mywi-htop-2.2.0/bin:
/nix/store/yifq4bikf7m07160bpia7z48ciqddbfi-tree-1.8.0/bin:

I think the new order makes more sense because it allows to override
the PATH in the outermost mkShell.
---
 pkgs/build-support/mkshell/default.nix | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

(limited to 'pkgs/build-support')

diff --git a/pkgs/build-support/mkshell/default.nix b/pkgs/build-support/mkshell/default.nix
index 698974590880..a70dc0390cb5 100644
--- a/pkgs/build-support/mkshell/default.nix
+++ b/pkgs/build-support/mkshell/default.nix
@@ -11,13 +11,8 @@
   ...
 }@attrs:
 let
-  mergeInputs = name:
-    let
-      op = item: sum: sum ++ item."${name}" or [];
-      nul = [];
-      list = [attrs] ++ inputsFrom;
-    in
-      lib.foldr op nul list;
+  mergeInputs = name: lib.concatLists (lib.catAttrs name
+    ([attrs] ++ inputsFrom));
 
   rest = builtins.removeAttrs attrs [
     "inputsFrom"
-- 
cgit 1.4.1