Merge pull request #111469 from sternenseemann/topretty-fix-currying

lib/generators: fix toPretty throwing on (partially applied) builtins

1 files changed, 9 insertions, 4 deletions

diff --git a/lib/generators.nix b/lib/generators.nix
index 501a23599f4..9546f5b5b0a 100644
--- a/lib/generators.nix
+++ b/lib/generators.nix
@@ -236,12 +236,17 @@ rec {
         + libStr.concatMapStringsSep introSpace (go (indent + "  ")) v
         + outroSpace + "]"
     else if isFunction v then
-      let fna = lib.functionArgs v;
+      # functionArgs throws in case of (partially applied) builtins
+      # on nix before commit b2748c6e99239ff6803ba0da76c362790c8be192
+      # which includes current nix stable
+      # TODO remove tryEval workaround when the issue is resolved on nix stable
+      let fna = builtins.tryEval (lib.functionArgs v);
           showFnas = concatStringsSep ", " (libAttr.mapAttrsToList
                        (name: hasDefVal: if hasDefVal then name + "?" else name)
-                       fna);
-      in if fna == {}    then "<function>"
-                         else "<function, args: {${showFnas}}>"
+                       fna.value);
+      in if !fna.success || fna.value == {}
+         then "<function>"
+         else "<function, args: {${showFnas}}>"
     else if isAttrs    v then
       # apply pretty values if allowed
       if attrNames v == [ "__pretty" "val" ] && allowPrettyValues