Make non-flake inputs lazy

Also add a proper test for non-flake inputs.

src/libexpr/primops/flake.cc

@@ -276,7 +276,7 @@ Flake getFlake(EvalState & state, const FlakeRef & flakeRef, bool impureIsAllowe
 }
 
 // Get the `NonFlake` corresponding to a `FlakeRef`.
-NonFlake getNonFlake(EvalState & state, const FlakeRef & flakeRef, FlakeAlias alias, bool impureIsAllowed = false)
+NonFlake getNonFlake(EvalState & state, const FlakeRef & flakeRef, bool impureIsAllowed = false)
 {
     auto sourceInfo = fetchFlake(state, flakeRef, impureIsAllowed);
     debug("got non-flake source '%s' with flakeref %s", sourceInfo.storePath, sourceInfo.resolvedRef.to_string());
@@ -290,8 +290,6 @@ NonFlake getNonFlake(EvalState & state, const FlakeRef & flakeRef, FlakeAlias al
     if (state.allowedPaths)
         state.allowedPaths->insert(nonFlake.sourceInfo.storePath);
 
-    nonFlake.alias = alias;
-
     return nonFlake;
 }
 
@@ -339,7 +337,7 @@ static std::pair<Flake, FlakeInput> updateLocks(
         } else {
             if (handleLockFile == AllPure || handleLockFile == TopRefUsesRegistries)
                 throw Error("cannot update non-flake dependency '%s' in pure mode", id);
-            auto nonFlake = getNonFlake(state, ref, id, allowedToUseRegistries(handleLockFile, false));
+            auto nonFlake = getNonFlake(state, ref, allowedToUseRegistries(handleLockFile, false));
             newEntry.nonFlakeInputs.insert_or_assign(id,
                 NonFlakeInput(
                     nonFlake.sourceInfo.resolvedRef,
@@ -441,6 +439,25 @@ static void prim_callFlake(EvalState & state, const Pos & pos, Value * * args, V
     callFlake(state, flake, *lazyFlake, v);
 }
 
+static void prim_callNonFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    auto lazyNonFlake = (NonFlakeInput *) args[0]->attrs;
+
+    auto nonFlake = getNonFlake(state, lazyNonFlake->ref);
+
+    if (nonFlake.sourceInfo.narHash != lazyNonFlake->narHash)
+        throw Error("the content hash of repository '%s' doesn't match the hash recorded in the referring lockfile", nonFlake.sourceInfo.resolvedRef);
+
+    state.mkAttrs(v, 8);
+
+    assert(state.store->isValidPath(nonFlake.sourceInfo.storePath));
+
+    mkString(*state.allocAttr(v, state.sOutPath),
+        nonFlake.sourceInfo.storePath, {nonFlake.sourceInfo.storePath});
+
+    emitSourceInfoAttrs(state, nonFlake.sourceInfo, v);
+}
+
 void callFlake(EvalState & state,
     const Flake & flake,
     const FlakeInputs & inputs,
@@ -468,16 +485,15 @@ void callFlake(EvalState & state,
 
     for (auto & dep : inputs.nonFlakeInputs) {
         auto vNonFlake = state.allocAttr(v, dep.first);
-        state.mkAttrs(*vNonFlake, 8);
-
-        auto nonFlake = getNonFlake(state, dep.second.ref, dep.first);
-
-        assert(state.store->isValidPath(nonFlake.sourceInfo.storePath));
-
-        mkString(*state.allocAttr(*vNonFlake, state.sOutPath),
-            nonFlake.sourceInfo.storePath, {nonFlake.sourceInfo.storePath});
-
-        emitSourceInfoAttrs(state, nonFlake.sourceInfo, *vNonFlake);
+        auto vPrimOp = state.allocValue();
+        static auto primOp = new PrimOp(prim_callNonFlake, 1, state.symbols.create("callNonFlake"));
+        vPrimOp->type = tPrimOp;
+        vPrimOp->primOp = primOp;
+        auto vArg = state.allocValue();
+        vArg->type = tNull;
+        // FIXME: leak
+        vArg->attrs = (Bindings *) new NonFlakeInput(dep.second); // evil! also inefficient
+        mkApp(*vNonFlake, *vPrimOp, *vArg);
     }
 
     mkString(*state.allocAttr(v, state.sDescription), flake.description);

src/libexpr/primops/flake.hh

@@ -75,7 +75,6 @@ struct Flake
 
 struct NonFlake
 {
-    FlakeAlias alias;
     FlakeRef originalRef;
     SourceInfo sourceInfo;
     NonFlake(const FlakeRef & origRef, const SourceInfo & sourceInfo)

src/nix/flake.cc

@@ -122,6 +122,7 @@ static nlohmann::json flakeToJson(const Flake & flake)
     return j;
 }
 
+#if 0
 static void printNonFlakeInfo(const NonFlake & nonFlake)
 {
     std::cout << fmt("ID:            %s\n", nonFlake.alias);
@@ -136,7 +137,6 @@ static nlohmann::json nonFlakeToJson(const NonFlake & nonFlake)
     return j;
 }
 
-#if 0
 // FIXME: merge info CmdFlakeInfo?
 struct CmdFlakeDeps : FlakeCommand
 {

tests/flakes.sh

@@ -83,7 +83,7 @@ git -C $flake3Dir add flake.nix
 git -C $flake3Dir commit -m 'Initial'
 
 cat > $nonFlakeDir/README.md <<EOF
-Not much
+FNORD
 EOF
 
 git -C $nonFlakeDir add README.md
@@ -235,23 +235,42 @@ cat > $flake3Dir/flake.nix <<EOF
   outputs = inputs: rec {
     packages.xyzzy = inputs.flake2.outputs.packages.bar;
     packages.sth = inputs.flake1.outputs.packages.foo;
+    packages.fnord =
+      with import ./config.nix;
+      mkDerivation {
+        inherit system;
+        name = "fnord";
+        buildCommand = ''
+          cat \${inputs.nonFlake}/README.md > \$out
+        '';
+      };
   };
 }
 EOF
 
-git -C $flake3Dir add flake.nix
+cp ./config.nix $flake3Dir
+
+git -C $flake3Dir add flake.nix config.nix
 git -C $flake3Dir commit -m 'Add nonFlakeInputs'
 
-# Check whether `nix build` works with a lockfile which is missing a nonFlakeInputs
+# Check whether `nix build` works with a lockfile which is missing a
+# nonFlakeInputs.
 nix build -o $TEST_ROOT/result --flake-registry $registry $flake3Dir:sth
 
 git -C $flake3Dir commit -m 'Update nonFlakeInputs'
 
+nix build -o $TEST_ROOT/result --flake-registry $registry flake3:fnord
+[[ $(cat $TEST_ROOT/result) = FNORD ]]
+
 # Check whether flake input fetching is lazy: flake3:sth does not
 # depend on flake2, so this shouldn't fail.
 rm -rf $TEST_HOME/.cache
 clearStore
 mv $flake2Dir $flake2Dir.tmp
+mv $nonFlakeDir $nonFlakeDir.tmp
 nix build -o $TEST_ROOT/result --flake-registry $registry flake3:sth
 (! nix build -o $TEST_ROOT/result --flake-registry $registry flake3:xyzzy)
+(! nix build -o $TEST_ROOT/result --flake-registry $registry flake3:fnord)
 mv $flake2Dir.tmp $flake2Dir
+mv $nonFlakeDir.tmp $nonFlakeDir
+nix build -o $TEST_ROOT/result --flake-registry $registry flake3:xyzzy flake3:fnord