From 328a3bbbd0c8ec4a51b85a813f09a6d2064f993a Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Fri, 17 Oct 2025 12:03:18 -0400
Subject: [PATCH 1/2] Regression test for issue #14287

This will currently fail, until the bug is fixed.

Co-Authored-By: Sergei Zimmerman <sergei@zimmerman.foo>
(cherry picked from commit 246dbe1c0554deda6eda2fd89855237294dcca5e)
---
 tests/functional/build-hook-list-paths.sh | 12 ++++++++++++
 tests/functional/post-hook.sh             | 12 ++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100755 tests/functional/build-hook-list-paths.sh

diff --git a/tests/functional/build-hook-list-paths.sh b/tests/functional/build-hook-list-paths.sh
new file mode 100755
index 000000000..03691c2d2
--- /dev/null
+++ b/tests/functional/build-hook-list-paths.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+set -x
+set -e
+
+[ -n "$OUT_PATHS" ]
+[ -n "$DRV_PATH" ]
+[ -n "$HOOK_DEST" ]
+
+for o in $OUT_PATHS; do
+    echo "$o" >> "$HOOK_DEST"
+done
diff --git a/tests/functional/post-hook.sh b/tests/functional/post-hook.sh
index 67bb46377..b16d8ab84 100755
--- a/tests/functional/post-hook.sh
+++ b/tests/functional/post-hook.sh
@@ -29,6 +29,18 @@ nix-build -o "$TEST_ROOT"/result dependencies.nix --post-build-hook "$pushToStor
 export BUILD_HOOK_ONLY_OUT_PATHS=$([ ! "$NIX_TESTS_CA_BY_DEFAULT" ])
 nix-build -o "$TEST_ROOT"/result-mult multiple-outputs.nix -A a.first --post-build-hook "$pushToStore"
 
+if isDaemonNewer "2.33.0pre20251029"; then
+    # Regression test for issue #14287: `--check` should re-run post build
+    # hook, even though nothing is getting newly registered.
+    export HOOK_DEST=$TEST_ROOT/listing
+    # Needed so the hook will get the above environment variable.
+    restartDaemon
+    nix-build -o "$TEST_ROOT"/result-mult multiple-outputs.nix --check -A a.first --post-build-hook "$PWD/build-hook-list-paths.sh"
+    grepQuiet a-first "$HOOK_DEST"
+    grepQuiet a-second "$HOOK_DEST"
+    unset HOOK_DEST
+fi
+
 clearStore
 
 # Ensure that the remote store contains both the runtime and build-time

From 9e4177bc674733ed5cec32c6ffdd12ee3ca16ece Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Fri, 17 Oct 2025 13:07:41 -0400
Subject: [PATCH 2/2] Fix issue #14287

The test added in the previous commit now passes.

Co-authored-by: Eelco Dolstra <edolstra@gmail.com>
(cherry picked from commit de192794c9f5a4dbd4fb6735277140f2161d9d79)
---
 src/libstore/build/derivation-building-goal.cc | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/libstore/build/derivation-building-goal.cc b/src/libstore/build/derivation-building-goal.cc
index 001816ca0..310b2bf84 100644
--- a/src/libstore/build/derivation-building-goal.cc
+++ b/src/libstore/build/derivation-building-goal.cc
@@ -860,7 +860,15 @@ Goal::Co DerivationBuildingGoal::tryToBuild()
     {
         builder.reset();
         StorePathSet outputPaths;
-        for (auto & [_, output] : builtOutputs) {
+        /* In the check case we install no store objects, and so
+           `builtOutputs` is empty. However, per issue #14287, there is
+           an expectation that the post-build hook is still executed.
+           (This is useful for e.g. logging successful deterministic rebuilds.)
+
+           In order to make that work, in the check case just load the
+           (preexisting) infos from scratch, rather than relying on what
+           `DerivationBuilder` returned to us. */
+        for (auto & [_, output] : buildMode == bmCheck ? checkPathValidity(initialOutputs).second : builtOutputs) {
             // for sake of `bmRepair`
             worker.markContentsGood(output.outPath);
             outputPaths.insert(output.outPath);