From e5ea01c1a8bbd328dcc576928bf3e4271cb55399 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 10 Apr 2020 10:24:09 +0200
Subject: Remove flake 'edition' field

Future editions of flakes or the Nix language can be supported by
renaming flake.nix (e.g. flake-v2.nix). This avoids a bootstrap
problem where we don't know which grammar to use to parse
flake*.nix. It also allows a project to support multiple flake
editions, in theory.
---
 src/libexpr/flake/call-flake.nix |  1 -
 src/libexpr/flake/flake.cc       | 20 ++++++--------------
 src/libexpr/flake/flake.hh       |  1 -
 3 files changed, 6 insertions(+), 16 deletions(-)

(limited to 'src/libexpr')

diff --git a/src/libexpr/flake/call-flake.nix b/src/libexpr/flake/call-flake.nix
index dc9ed357c..8ee17b8f4 100644
--- a/src/libexpr/flake/call-flake.nix
+++ b/src/libexpr/flake/call-flake.nix
@@ -19,7 +19,6 @@ let
           result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
         in
           if node.flake or true then
-            assert flake.edition or flake.epoch or 0 == 201909;
             assert builtins.isFunction flake.outputs;
             result
           else
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 86bb05b5d..212eceeac 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -231,22 +231,14 @@ static Flake getFlake(
 
     expectType(state, tAttrs, vInfo, Pos(state.symbols.create(flakeFile), 0, 0));
 
-    auto sEdition = state.symbols.create("edition");
+    auto sEdition = state.symbols.create("edition"); // FIXME: remove soon
     auto sEpoch = state.symbols.create("epoch"); // FIXME: remove soon
 
-    auto edition = vInfo.attrs->get(sEdition);
-    if (!edition)
-        edition = vInfo.attrs->get(sEpoch);
-
-    if (edition) {
-        expectType(state, tInt, *edition->value, *edition->pos);
-        flake.edition = edition->value->integer;
-        if (flake.edition > 201909)
-            throw Error("flake '%s' requires unsupported edition %d; please upgrade Nix", lockedRef, flake.edition);
-        if (flake.edition < 201909)
-            throw Error("flake '%s' has illegal edition %d", lockedRef, flake.edition);
-    } else
-        throw Error("flake '%s' lacks attribute 'edition'", lockedRef);
+    if (vInfo.attrs->get(sEdition))
+        warn("flake '%s' has deprecated attribution 'edition'", lockedRef);
+
+    if (vInfo.attrs->get(sEpoch))
+        warn("flake '%s' has deprecated attribution 'epoch'", lockedRef);
 
     if (auto description = vInfo.attrs->get(state.sDescription)) {
         expectType(state, tString, *description->value, *description->pos);
diff --git a/src/libexpr/flake/flake.hh b/src/libexpr/flake/flake.hh
index 7ee9bbe76..107498c1b 100644
--- a/src/libexpr/flake/flake.hh
+++ b/src/libexpr/flake/flake.hh
@@ -34,7 +34,6 @@ struct Flake
     std::shared_ptr<const fetchers::Tree> sourceInfo;
     FlakeInputs inputs;
     Value * vOutputs; // FIXME: gc
-    unsigned int edition;
     ~Flake();
 };
 
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