From 73910d39d13e2e06911df41c5e792b16f261c653 Mon Sep 17 00:00:00 2001
From: Uluc Sengil <uluc.sengil@helsing.ai>
Date: Tue, 10 Jun 2025 14:14:43 +0200
Subject: [PATCH] add layers to catching IFDs in `nix flake show`

---
 src/nix/flake.cc | 39 ++++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 95cf85663..6d8468461 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -1206,10 +1206,15 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                         || attrPathS[0] == "legacyPackages"
                         || attrPathS[0] == "packages")
                     && (attrPathS.size() == 1 || attrPathS.size() == 2)) {
-                    for (const auto &subAttr : visitor2->getAttrs()) {
-                        if (hasContent(*visitor2, attrPath2, subAttr)) {
-                            return true;
+                    try {
+                        for (const auto &subAttr : visitor2->getAttrs()) {
+                            if (hasContent(*visitor2, attrPath2, subAttr)) {
+                                return true;
+                            }
                         }
+                    } catch (IFDError & e) {
+                        // allow IFD errors here; as we handle them during `visit()`
+                        return true;
                     }
                     return false;
                 }
@@ -1220,10 +1225,14 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                         || attrPathS[0] == "nixosModules"
                         || attrPathS[0] == "overlays"
                         )) {
-                    for (const auto &subAttr : visitor2->getAttrs()) {
-                        if (hasContent(*visitor2, attrPath2, subAttr)) {
-                            return true;
+                    try {
+                        for (const auto &subAttr : visitor2->getAttrs()) {
+                            if (hasContent(*visitor2, attrPath2, subAttr)) {
+                                return true;
+                            }
                         }
+                    } catch (IFDError & e) {
+                        return true;
                     }
                     return false;
                 }
@@ -1261,12 +1270,20 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
             try {
                 auto recurse = [&]()
                 {
-                    if (!json)
-                        logger->cout("%s", headerPrefix);
                     std::vector<Symbol> attrs;
-                    for (const auto &attr : visitor.getAttrs()) {
-                        if (hasContent(visitor, attrPath, attr))
-                            attrs.push_back(attr);
+                    try {
+                        for (const auto &attr : visitor.getAttrs()) {
+                            if (hasContent(visitor, attrPath, attr))
+                                attrs.push_back(attr);
+                        }
+                        if (!json)
+                            logger->cout("%s", headerPrefix);
+                    } catch (IFDError & e) {
+                        if (!json) {
+                            logger->cout(fmt("%s " ANSI_WARNING "omitted due to use of import from derivation" ANSI_NORMAL, headerPrefix));
+                        } else {
+                            logger->warn(fmt("%s omitted due to use of import from derivation", concatStringsSep(".", attrPathS)));
+                        }
                     }
 
                     for (const auto & [i, attr] : enumerate(attrs)) {