sourceInputCompletionHook: init

pkgs/shells/hooks/sourceInputCompletionHook/default.nix

@@ -0,0 +1,8 @@
+{ makeSetupHook, findutils, substituteAll }:
+
+# See the header comment in ./source-input-completion-hook.sh for example usage.
+makeSetupHook { name = "source-input-completion-hook"; } (
+  substituteAll {
+    src = ./source-input-completion-hook.sh;
+    inherit findutils;
+  })

pkgs/shells/hooks/sourceInputCompletionHook/source-input-completion-hook.sh

@@ -0,0 +1,40 @@
+
+# This function is meant to inspect the inputs to a derivation and source the shell completion.
+# This is intended to be only used with nix-shell to provide a better user experience, and is not
+# intended to be used within nixpkgs as shell completion is only useful in an interactive shell.
+sourceInputCompletion() {
+    local completionPath=
+
+    case $(basename $SHELL) in
+        bash)
+            completionPath=share/bash-completion/completions/
+            ;;
+        fish)
+            completionPath=share/fish/vendor_completions.d/
+            ;;
+        zsh)
+            completionPath=share/zsh/site-functions/
+            ;;
+        *)
+            echo "$(basename $SHELL) is not supported for shell completion. Skipping."
+            exit 0
+    esac
+
+    declare -A inputsSourced
+    for input in $nativeBuildInputs $buildInputs $propagatedNativeBuildInputs $propagatedBuildInputs; do
+        local completionDir=$input/$completionPath
+        if [ -d $completionDir ]; then
+            for script in $(@findutils@/bin/find $completionDir -type f); do
+                . $script
+                # grab derivation pname. E.g. /nix/store/...-kubectl-1.19.4 -> kubectl
+                inputsSourced[$(echo $input | sed -e 's/[^-]*-//' | sed -e 's/-.*$//')]=1
+            done
+        fi
+    done
+
+    echo "Completions added for: ${!inputsSourced[@]}"
+}
+
+if [ -z "$dontUseSourceInputCompletion" ]; then
+  sourceInputCompletion
+fi

pkgs/top-level/all-packages.nix

@@ -161,6 +161,8 @@ in
     deps = [ innoextract file-rename ]; }
     ../build-support/setup-hooks/gog-unpack.sh;
 
+  sourceInputCompletionHook = callPackage ../shells/hooks/sourceInputCompletionHook { };
+
   buildEnv = callPackage ../build-support/buildenv { }; # not actually a package
 
   # TODO: eventually migrate everything to buildFHSUserEnvBubblewrap