From 0afab668fa3f20f091dec0a31fc0b0fbaac2afde Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 3 Dec 2020 13:19:20 +0100
Subject: [PATCH 1/2] Don't fail early when -j0 is passed

If the build closure contains some CA derivations, then we can't know
ahead-of-time that we won't build anything as early-cutoff might come-in
at a laster stage
---
 src/libstore/build/worker.cc | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/src/libstore/build/worker.cc b/src/libstore/build/worker.cc
index 1f8999a4b..6c96a93bd 100644
--- a/src/libstore/build/worker.cc
+++ b/src/libstore/build/worker.cc
@@ -223,11 +223,6 @@ void Worker::run(const Goals & _topGoals)
     uint64_t downloadSize, narSize;
     store.queryMissing(topPaths, willBuild, willSubstitute, unknown, downloadSize, narSize);
 
-    if (!willBuild.empty() && 0 == settings.maxBuildJobs && getMachines().empty())
-        throw Error(
-            "%d derivations need to be built, but neither local builds ('--max-jobs') "
-            "nor remote builds ('--builders') are enabled", willBuild.size());
-
     debug("entered goal loop");
 
     while (1) {

From 8ad72b1f1c272d01d5d67b21553fc261c8df5302 Mon Sep 17 00:00:00 2001
From: regnat <rg@regnat.ovh>
Date: Thu, 3 Dec 2020 13:20:53 +0100
Subject: [PATCH 2/2] Properly test early cutoff with CA derivations

Build things with a different seed each time to make sure that it works
despite the different drvs
---
 tests/content-addressed.sh | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/tests/content-addressed.sh b/tests/content-addressed.sh
index 52f7529b5..03eff549c 100644
--- a/tests/content-addressed.sh
+++ b/tests/content-addressed.sh
@@ -7,30 +7,32 @@ nix --experimental-features 'nix-command ca-derivations' show-derivation --deriv
 
 buildAttr () {
     local derivationPath=$1
-    shift
-    local args=("--experimental-features" "ca-derivations" "./content-addressed.nix" "-A" "$derivationPath" "--no-out-link")
+    local seedValue=$2
+    shift; shift
+    local args=("--experimental-features" "ca-derivations" "./content-addressed.nix" "-A" "$derivationPath" --arg seed "$seedValue" "--no-out-link")
     args+=("$@")
     nix-build "${args[@]}"
 }
 
 testRemoteCache () {
     clearCache
-    local outPath=$(buildAttr dependentNonCA)
+    local outPath=$(buildAttr dependentNonCA 1)
     nix copy --to file://$cacheDir $outPath
     clearStore
-    buildAttr dependentNonCA --option substituters file://$cacheDir --no-require-sigs |& (! grep "building dependent-non-ca")
+    buildAttr dependentNonCA 1 --option substituters file://$cacheDir --no-require-sigs |& (! grep "building dependent-non-ca")
 }
 
 testDeterministicCA () {
-    [[ $(buildAttr rootCA) = $(buildAttr rootCA) ]]
+    [[ $(buildAttr rootCA 1) = $(buildAttr rootCA 2) ]]
 }
 
 testCutoffFor () {
     local out1 out2
-    out1=$(buildAttr $1)
+    out1=$(buildAttr $1 1)
     # The seed only changes the root derivation, and not it's output, so the
     # dependent derivations should only need to be built once.
-    out2=$(buildAttr $1 -j0)
+    buildAttr rootCA 2
+    out2=$(buildAttr $1 2 -j0)
     test "$out1" == "$out2"
 }