Merge pull request #8350 from NixOS/backport-8154-to-2.15-maintenance

[Backport 2.15-maintenance] Make `nix-collect-garbage -d` look into more places

src/nix-collect-garbage/nix-collect-garbage.cc

@@ -77,7 +77,12 @@ static int main_nix_collect_garbage(int argc, char * * argv)
             return true;
         });
 
-        if (removeOld) removeOldGenerations(profilesDir());
+        if (removeOld) {
+            std::set<Path> dirsToClean = {
+                profilesDir(), settings.nixStateDir + "/profiles", dirOf(getDefaultProfile())};
+            for (auto & dir : dirsToClean)
+                removeOldGenerations(dir);
+        }
 
         // Run the actual garbage collector.
         if (!dryRun) {

tests/gc.sh

@@ -52,9 +52,7 @@ rmdir $NIX_STORE_DIR/.links
 rmdir $NIX_STORE_DIR
 
 ## Test `nix-collect-garbage -d`
-# `nix-env` doesn't work with CA derivations, so let's ignore that bit if we're
+testCollectGarbageD () {
-# using them
-if [[ -z "${NIX_TESTS_CA_BY_DEFAULT:-}" ]]; then
     clearProfiles
     # Run two `nix-env` commands, should create two generations of
     # the profile
@@ -66,4 +64,17 @@ if [[ -z "${NIX_TESTS_CA_BY_DEFAULT:-}" ]]; then
     # left
     nix-collect-garbage -d
     [[ $(nix-env --list-generations | wc -l) -eq 1 ]]
+}
+# `nix-env` doesn't work with CA derivations, so let's ignore that bit if we're
+# using them
+if [[ -z "${NIX_TESTS_CA_BY_DEFAULT:-}" ]]; then
+    testCollectGarbageD
+
+    # Run the same test, but forcing the profiles at their legacy location under
+    # /nix/var/nix.
+    #
+    # Regression test for #8294
+    rm ~/.nix-profile
+    ln -s $NIX_STATE_DIR/profiles/per-user/me ~/.nix-profile
+    testCollectGarbageD
 fi