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

This reverts commit d9a7d03da8c58aa863911506ae3153729f8931da.

Reason for this is that it actually doesn't migitate the issue on nix
stable for another reason: builtins.tryEval doesn't prevent the error
generated by builtins.functionArgs from halting evaluation:

> builtins.tryEval (builtins.functionArgs builtins.functionArgs)
error: 'functionArgs' requires a function, at (string):1:19

Thus it seems that there is no workaround to make
lib.generators.toPretty work with nix stable and primops since there is
no way to distinguish between primops and lambdas in nix.

1 files changed, 4 insertions, 9 deletions

diff --git a/lib/generators.nix b/lib/generators.nix
index 9546f5b5b0ab..501a23599f45 100644
--- a/lib/generators.nix
+++ b/lib/generators.nix
@@ -236,17 +236,12 @@ rec {
         + libStr.concatMapStringsSep introSpace (go (indent + "  ")) v
         + outroSpace + "]"
     else if isFunction v then
-      # 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);
+      let fna = lib.functionArgs v;
           showFnas = concatStringsSep ", " (libAttr.mapAttrsToList
                        (name: hasDefVal: if hasDefVal then name + "?" else name)
-                       fna.value);
-      in if !fna.success || fna.value == {}
-         then "<function>"
-         else "<function, args: {${showFnas}}>"
+                       fna);
+      in if fna == {}    then "<function>"
+                         else "<function, args: {${showFnas}}>"
     else if isAttrs    v then
       # apply pretty values if allowed
       if attrNames v == [ "__pretty" "val" ] && allowPrettyValues