libexpr: Migrate EvalState::autoCallFunction to return a Value

Change-Id: I426c3d413b18848090dd05674a08e5fb6a6a6964

lix/legacy/nix-instantiate.cc

@@ -46,7 +46,7 @@ void processExpr(EvalState & state, const Strings & attrPaths,
             if (autoArgs.empty())
                 vRes = v;
             else
-                state.autoCallFunction(autoArgs, v, vRes, noPos);
+                vRes = state.autoCallFunction(autoArgs, v, noPos);
             if (output == okRaw)
                 std::cout << *state.coerceToString(noPos, vRes, context, "while generating the nix-instantiate output", StringCoercionMode::Strict);
                 // We intentionally don't output a newline here. The default PS1 for Bash in NixOS starts with a newline

lix/libcmd/installables.cc

@@ -236,8 +236,7 @@ void SourceExprCommand::completeInstallable(EvalState & state, AddCompletions &
 
             auto [v1, pos] = findAlongAttrPath(state, prefix_, *autoArgs, root);
             state.forceValue(v1, pos);
-            Value v2;
-            state.autoCallFunction(*autoArgs, v1, v2, pos);
+            Value v2 = state.autoCallFunction(*autoArgs, v1, pos);
 
             if (v2.type() == nAttrs) {
                 for (auto & i : *v2.attrs()) {

lix/libcmd/repl.cc

@@ -1288,9 +1288,8 @@ void NixRepl::loadFile(const Path & path)
     try {
         loaded.remove(loadable);
         loaded.push_back(loadable);
-        Value v2;
         Value v = state.evalFile(state.aio.blockOn(lookupFileArg(evaluator, path)).unwrap(always_progresses));
-        state.autoCallFunction(*autoArgs, v, v2, noPos);
+        Value v2 = state.autoCallFunction(*autoArgs, v, noPos);
         addAttrsToScope(v2);
     } catch (...) {
         // In case of failure, do not keep the loaded path.

lix/libexpr/attr-path.cc

@@ -83,9 +83,7 @@ findAlongAttrPath(EvalState & state, const std::string & attrPath, Bindings & au
         auto attrIndex = string2Int<unsigned int>(attr);
 
         /* Evaluate the expression. */
-        Value vNew;
-        state.autoCallFunction(autoArgs, v, vNew, pos);
-        v = vNew;
+        v = state.autoCallFunction(autoArgs, v, pos);
         state.forceValue(v, noPos);
 
         /* It should evaluate to either a set or an expression,

lix/libexpr/eval.cc

@@ -1306,8 +1306,7 @@ void EvalStatistics::addCall(ExprLambda & fun)
     functionCalls[&fun]++;
 }
 
-
-void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res, PosIdx pos)
+Value EvalState::autoCallFunction(Bindings & args, Value & fun, PosIdx pos)
 {
     forceValue(fun, pos);
 
@@ -1316,18 +1315,16 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res, PosI
         if (found) {
             Value v = callFunction(found->value, fun, pos);
             forceValue(v, pos);
-            return autoCallFunction(args, v, res, pos);
+            return autoCallFunction(args, v, pos);
         }
     }
 
     if (!fun.isLambda()) {
-        res = fun;
-        return;
+        return fun;
     }
     auto pattern = dynamic_cast<AttrsPattern *>(fun.lambda().fun->pattern.get());
     if (!pattern) {
-        res = fun;
-        return;
+        return fun;
     }
 
     auto attrs = ctx.buildBindings(std::max(static_cast<uint32_t>(pattern->formals.size()), args.size()));
@@ -1362,7 +1359,7 @@ https://docs.lix.systems/manual/lix/stable/language/constructs.html#functions)",
     }
 
     Value vAttrs{NewValueAs::attrs, attrs.finish()};
-    res = callFunction(fun, vAttrs, pos);
+    return callFunction(fun, vAttrs, pos);
 }
 
 void EvalState::concatLists(

lix/libexpr/eval.hh

@@ -798,7 +798,7 @@ public:
      * Automatically call a function for which each argument has a
      * default value or has a binding in the `args` map.
      */
-    void autoCallFunction(Bindings & args, Value & fun, Value & res, PosIdx pos);
+    Value autoCallFunction(Bindings & args, Value & fun, PosIdx pos);
 
     void mkPos(Value & v, PosIdx pos);
 

lix/libexpr/get-drvs.cc

@@ -451,8 +451,7 @@ static void getDerivations(EvalState & state, Value & vIn, PosIdx pos,
     DrvInfos & drvs, Done & done,
     bool ignoreAssertionFailures)
 {
-    Value v;
-    state.autoCallFunction(autoArgs, vIn, v, pos);
+    Value v = state.autoCallFunction(autoArgs, vIn, pos);
 
     bool shouldRecurse = getDerivation(state, v, pathPrefix, drvs, ignoreAssertionFailures);
     if (!shouldRecurse) {

lix/nix/repl.cc

@@ -68,8 +68,7 @@ struct CmdRepl : RawInstallablesCommand
                     auto what = installable.what();
                     state->forceValue(val, pos);
                     auto autoArgs = getAutoArgs(*evaluator);
-                    Value valPost;
-                    state->autoCallFunction(*autoArgs, val, valPost, pos);
+                    Value valPost = state->autoCallFunction(*autoArgs, val, pos);
                     state->forceValue(valPost, pos);
                     values.push_back( {valPost, what });
                 } else {

subprojects/nix-eval-jobs/src/worker.cc

@@ -57,11 +57,7 @@ static nix::Value releaseExprTopLevelValue(nix::EvalState &state,
                 .unwrap());
     }
 
-    nix::Value vRoot;
-
-    state.autoCallFunction(autoArgs, vTop, vRoot, {});
-
-    return vRoot;
+    return state.autoCallFunction(autoArgs, vTop, {});
 }
 
 static std::string attrPathJoin(nix::JSON input) {
@@ -196,8 +192,7 @@ try {
                 nix::findAlongAttrPath(*state, attrPathS, autoArgs, vRoot)
                     .first;
 
-            nix::Value v;
-            state->autoCallFunction(autoArgs, vTmp, v, {});
+            nix::Value v = state->autoCallFunction(autoArgs, vTmp, {});
 
             if (v.type() == nix::nAttrs) {
                 if (auto drvInfo = nix::getDerivation(*state, v, false)) {