libexpr: Migrate callFlake to return a Value

Change-Id: Ibdac6eb1c9dfda894d783a7b6e333f486a6a6964

lix/libcmd/installables.cc

@@ -409,8 +409,7 @@ ref<eval_cache::EvalCache> openEvalCache(
             if (getEnv("NIX_ALLOW_EVAL").value_or("1") == "0")
                 throw Error("not everything is cached, but evaluation is not allowed");
 
-            Value vFlake;
-            flake::callFlake(state, *lockedFlake, vFlake);
+            Value vFlake = flake::callFlake(state, *lockedFlake);
 
             state.forceAttrs(vFlake, noPos, "while parsing cached flake data");
 

lix/libcmd/repl.cc

@@ -1318,7 +1318,7 @@ void NixRepl::loadFlake(const std::string & flakeRefS)
     try {
         loaded.remove(loadable);
         loaded.push_back(loadable);
-        flake::callFlake(
+        v = flake::callFlake(
             state,
             flake::lockFlake(
                 state,
@@ -1328,8 +1328,7 @@ void NixRepl::loadFlake(const std::string & flakeRefS)
                     .useRegistries = !evalSettings.pureEval,
                     .allowUnlocked = !evalSettings.pureEval,
                 }
-            ),
-            v
+            )
         );
         addAttrsToScope(v);
     } catch (...) {

lix/libexpr/flake/flake.cc

@@ -940,9 +940,7 @@ LockedFlake lockFlake(
     }
 }
 
-void callFlake(EvalState & state,
-    const LockedFlake & lockedFlake,
-    Value & vRes)
+Value callFlake(EvalState & state, const LockedFlake & lockedFlake)
 {
     Value vLocks;
     Value vRootSrc;
@@ -971,7 +969,7 @@ void callFlake(EvalState & state,
 
     Value vTmp1 = state.callFunction(*state.ctx.caches.vCallFlake, vLocks, noPos);
     Value vTmp2 = state.callFunction(vTmp1, vRootSrc, noPos);
-    vRes = state.callFunction(vTmp2, vRootSubdir, noPos);
+    return state.callFunction(vTmp2, vRootSubdir, noPos);
 }
 
 void prim_getFlake(EvalState & state, Value * * args, Value & v)
@@ -981,15 +979,19 @@ void prim_getFlake(EvalState & state, Value * * args, Value & v)
     if (evalSettings.pureEval && !flakeRef.input.isLocked())
         throw Error("cannot call 'getFlake' on unlocked flake reference '%s' (use --impure to override)", flakeRefS);
 
-    callFlake(state,
-        lockFlake(state, flakeRef,
-            LockFlags {
+    v = callFlake(
+        state,
+        lockFlake(
+            state,
+            flakeRef,
+            LockFlags{
                 .updateLockFile = false,
                 .writeLockFile = false,
                 .useRegistries = !evalSettings.pureEval && fetchSettings.useRegistries,
                 .allowUnlocked = !evalSettings.pureEval,
-            }),
-        v);
+            }
+        )
+    );
 }
 
 void prim_parseFlakeRef(

lix/libexpr/flake/flake.hh

@@ -199,11 +199,7 @@ LockedFlake lockFlake(
     const FlakeRef & flakeRef,
     const LockFlags & lockFlags);
 
-void callFlake(
-    EvalState & state,
-    const LockedFlake & lockedFlake,
-    Value & v);
-
+Value callFlake(EvalState & state, const LockedFlake & lockedFlake);
 }
 
 void emitTreeAttrs(

lix/nix/flake.cc

@@ -596,8 +596,7 @@ struct CmdFlakeCheck : FlakeCommand
         {
             auto act = logger->startActivity(lvlInfo, actUnknown, "evaluating flake");
 
-            Value vFlake;
-            flake::callFlake(*state, flake, vFlake);
+            Value vFlake = flake::callFlake(*state, flake);
 
             enumerateOutputs(
                 *state,