Merge pull request #5839 from tweag/balsoft/yet-another-follows-bugfix

flake.cc: computeLocks: Only verify overrides when they could change

2 files changed, 25 insertions, 21 deletions

diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index b15878d5c..c549c5971 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -344,7 +344,8 @@ LockedFlake lockFlake(
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
             const LockParent & parent,
-            const Path & parentPath)>
+            const Path & parentPath,
+            bool trustLock)>
             computeLocks;
 
         computeLocks = [&](
@@ -353,7 +354,8 @@ LockedFlake lockFlake(
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
             const LockParent & parent,
-            const Path & parentPath)
+            const Path & parentPath,
+            bool trustLock)
         {
             debug("computing lock file node '%s'", printInputPath(inputPathPrefix));
 
@@ -464,14 +466,20 @@ LockedFlake lockFlake(
                                         .isFlake = (*lockedNode)->isFlake,
                                     });
                                 } else if (auto follows = std::get_if<1>(&i.second)) {
-                                    auto o = input.overrides.find(i.first);
-                                    // If the override disappeared, we have to refetch the flake,
-                                    // since some of the inputs may not be present in the lockfile.
-                                    if (o == input.overrides.end()) {
-                                        mustRefetch = true;
-                                        // There's no point populating the rest of the fake inputs,
-                                        // since we'll refetch the flake anyways.
-                                        break;
+                                    if (! trustLock) {
+                                        // It is possible that the flake has changed,
+                                        // so we must confirm all the follows that are in the lockfile are also in the flake.
+                                        auto overridePath(inputPath);
+                                        overridePath.push_back(i.first);
+                                        auto o = overrides.find(overridePath);
+                                        // If the override disappeared, we have to refetch the flake,
+                                        // since some of the inputs may not be present in the lockfile.
+                                        if (o == overrides.end()) {
+                                            mustRefetch = true;
+                                            // There's no point populating the rest of the fake inputs,
+                                            // since we'll refetch the flake anyways.
+                                            break;
+                                        }
                                     }
                                     fakeInputs.emplace(i.first, FlakeInput {
                                         .follows = *follows,
@@ -482,14 +490,14 @@ LockedFlake lockFlake(
 
                         LockParent newParent {
                             .path = inputPath,
-                            .absolute = false
+                            .absolute = true
                         };
 
                         computeLocks(
                             mustRefetch
                             ? getFlake(state, oldLock->lockedRef, false, flakeCache).inputs
                             : fakeInputs,
-                            childNode, inputPath, oldLock, newParent, parentPath);
+                            childNode, inputPath, oldLock, newParent, parentPath, !mustRefetch);
 
                     } else {
                         /* We need to create a new lock file entry. So fetch
@@ -546,7 +554,7 @@ LockedFlake lockFlake(
                                 ? std::dynamic_pointer_cast<const Node>(oldLock)
                                 : LockFile::read(
                                     inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root,
-                                newParent, localPath);
+                                newParent, localPath, false);
                         }
 
                         else {
@@ -574,7 +582,7 @@ LockedFlake lockFlake(
 
         computeLocks(
             flake.inputs, newLockFile.root, {},
-            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath);
+            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath, false);
 
         for (auto & i : lockFlags.inputOverrides)
             if (!overridesUsed.count(i.first))
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 942d07010..20e6d09c1 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -716,11 +716,10 @@ cat > $flakeFollowsA/flake.nix <<EOF
     inputs = {
         B = {
             url = "path:./flakeB";
-            inputs.foobar.follows = "D";
-            inputs.nonFlake.follows = "D";
+            inputs.foobar.follows = "foobar";
         };
 
-        D.url = "path:./flakeD";
+        foobar.url = "path:$flakeFollowsA/flakeE";
     };
     outputs = { ... }: {};
 }
@@ -731,8 +730,6 @@ cat > $flakeFollowsB/flake.nix <<EOF
     description = "Flake B";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
-        nonFlake.url = "path:$nonFlakeDir";
-        goodoo.follows = "C/goodoo";
         C = {
             url = "path:./flakeC";
             inputs.foobar.follows = "foobar";
@@ -747,7 +744,6 @@ cat > $flakeFollowsC/flake.nix <<EOF
     description = "Flake C";
     inputs = {
         foobar.url = "path:$flakeFollowsA/flakeE";
-        goodoo.follows = "foobar";
     };
     outputs = { ... }: {};
 }
@@ -785,7 +781,7 @@ newLock="$(cat "$flakeFollowsA/flake.lock")"
 diff <(echo "$newLock") <(echo "$oldLock")
 
 [[ $(jq -c .nodes.B.inputs.C $flakeFollowsA/flake.lock) = '"C"' ]]
-[[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["D"]' ]]
+[[ $(jq -c .nodes.B.inputs.foobar $flakeFollowsA/flake.lock) = '["foobar"]' ]]
 [[ $(jq -c .nodes.C.inputs.foobar $flakeFollowsA/flake.lock) = '["B","foobar"]' ]]
 
 # Ensure removing follows from flake.nix removes them from the lockfile