1 files changed, 20 insertions, 3 deletions

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index d8e10d9f2..2789ea313 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -7,6 +7,7 @@
 #include "eval-inline.hh"
 #include "download.hh"
 #include "json.hh"
+#include "primops/flake.hh"
 
 #include <algorithm>
 #include <cstring>
@@ -302,6 +303,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sOutputHash(symbols.create("outputHash"))
     , sOutputHashAlgo(symbols.create("outputHashAlgo"))
     , sOutputHashMode(symbols.create("outputHashMode"))
+    , sDescription(symbols.create("description"))
     , repair(NoRepair)
     , store(store)
     , baseEnv(allocEnv(128))
@@ -451,14 +453,21 @@ Value * EvalState::addConstant(const string & name, Value & v)
 Value * EvalState::addPrimOp(const string & name,
     size_t arity, PrimOpFun primOp)
 {
+    auto name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
+    Symbol sym = symbols.create(name2);
+
+    /* Hack to make constants lazy: turn them into a application of
+       the primop to a dummy value. */
     if (arity == 0) {
+        auto vPrimOp = allocValue();
+        vPrimOp->type = tPrimOp;
+        vPrimOp->primOp = new PrimOp(primOp, 1, sym);
         Value v;
-        primOp(*this, noPos, nullptr, v);
+        mkApp(v, *vPrimOp, *vPrimOp);
         return addConstant(name, v);
     }
+
     Value * v = allocValue();
-    string name2 = string(name, 0, 2) == "__" ? string(name, 2) : name;
-    Symbol sym = symbols.create(name2);
     v->type = tPrimOp;
     v->primOp = new PrimOp(primOp, arity, sym);
     staticBaseEnv.vars[symbols.create(name)] = baseEnvDispl;
@@ -1969,6 +1978,14 @@ std::ostream & operator << (std::ostream & str, const ExternalValueBase & v) {
 
 EvalSettings evalSettings;
 
+EvalSettings::EvalSettings()
+{
+    if (flakeRegistry == "")
+        // FIXME: static initialization order fiasco. But this will go
+        // away when we switch to an online registry.
+        flakeRegistry = settings.nixDataDir + "/nix/flake-registry.json";
+}
+
 static GlobalConfig::Register r1(&evalSettings);