From d9a6a75ed28c590dde2dba846e356cbcda38d977 Mon Sep 17 00:00:00 2001
From: Nick Van den Broeck <nick.van.den.broeck666@gmail.com>
Date: Mon, 3 Jun 2019 14:47:47 +0200
Subject: [PATCH] Made epochs more fine-grained Fixes #2894

---
 doc/flakes/design.md         |  4 ++--
 flake.nix                    |  2 +-
 src/libexpr/primops/flake.cc |  2 +-
 src/nix/flake-template.nix   |  2 +-
 tests/flakes.sh              | 12 ++++++------
 5 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/doc/flakes/design.md b/doc/flakes/design.md
index 4f6524f83..63198e577 100644
--- a/doc/flakes/design.md
+++ b/doc/flakes/design.md
@@ -96,7 +96,7 @@ module.
 
   # The epoch may be used in the future to determine how Nix
   # expressions inside this flake are to be parsed.
-  epoch = 2018;
+  epoch = 201906;
 
   # Some other metadata.
   description = "A filesystem that fetches DWARF debug info from the Internet on demand";
@@ -164,7 +164,7 @@ Similarly, a minimal `flake.nix` for Nixpkgs:
 {
   name = "nixpkgs";
 
-  epoch = 2018;
+  epoch = 201906;
 
   description = "A collection of packages for the Nix package manager";
 
diff --git a/flake.nix b/flake.nix
index ab96d5c90..e7deb2de3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -3,7 +3,7 @@
 
   description = "The purely functional package manager";
 
-  epoch = 2019;
+  epoch = 201906;
 
   inputs = [ "nixpkgs" ];
 
diff --git a/src/libexpr/primops/flake.cc b/src/libexpr/primops/flake.cc
index 235e10922..e5035c53a 100644
--- a/src/libexpr/primops/flake.cc
+++ b/src/libexpr/primops/flake.cc
@@ -312,7 +312,7 @@ Flake getFlake(EvalState & state, const FlakeRef & flakeRef, bool impureIsAllowe
 
     if (auto epoch = vInfo.attrs->get(sEpoch)) {
         flake.epoch = state.forceInt(*(**epoch).value, *(**epoch).pos);
-        if (flake.epoch > 2019)
+        if (flake.epoch > 201906)
             throw Error("flake '%s' requires unsupported epoch %d; please upgrade Nix", flakeRef, flake.epoch);
     } else
         throw Error("flake '%s' lacks attribute 'epoch'", flakeRef);
diff --git a/src/nix/flake-template.nix b/src/nix/flake-template.nix
index fe89e647e..bec613f6c 100644
--- a/src/nix/flake-template.nix
+++ b/src/nix/flake-template.nix
@@ -3,7 +3,7 @@
 
   description = "A flake for building Hello World";
 
-  epoch = 2019;
+  epoch = 201906;
 
   requires = [ "nixpkgs" ];
 
diff --git a/tests/flakes.sh b/tests/flakes.sh
index c4dd8c333..998abfd09 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -29,7 +29,7 @@ cat > $flake1Dir/flake.nix <<EOF
 {
   name = "flake1";
 
-  epoch = 2019;
+  epoch = 201906;
 
   description = "Bla bla";
 
@@ -48,7 +48,7 @@ cat > $flake2Dir/flake.nix <<EOF
 {
   name = "flake2";
 
-  epoch = 2019;
+  epoch = 201906;
 
   inputs = [ "flake1" ];
 
@@ -67,7 +67,7 @@ cat > $flake3Dir/flake.nix <<EOF
 {
   name = "flake3";
 
-  epoch = 2019;
+  epoch = 201906;
 
   inputs = [ "flake2" ];
 
@@ -169,7 +169,7 @@ cat > $flake3Dir/flake.nix <<EOF
 {
   name = "flake3";
 
-  epoch = 2019;
+  epoch = 201906;
 
   inputs = [ "flake1" "flake2" ];
 
@@ -192,7 +192,7 @@ nix build -o $TEST_ROOT/result --flake-registry $registry $flake3Dir:sth
 [[ ! (-z $(git -C $flake3Dir diff master)) ]]
 
 # Unsupported epochs should be an error.
-sed -i $flake3Dir/flake.nix -e s/2019/2030/
+sed -i $flake3Dir/flake.nix -e s/201906/201909/
 nix build -o $TEST_ROOT/result --flake-registry $registry $flake3Dir:sth 2>&1 | grep 'unsupported epoch'
 
 # Test whether registry caching works.
@@ -219,7 +219,7 @@ cat > $flake3Dir/flake.nix <<EOF
 {
   name = "flake3";
 
-  epoch = 2019;
+  epoch = 201906;
 
   inputs = [ "flake1" "flake2" ];