No global eval settings in libnixexpr

Progress on #5638

There is still a global eval settings, but it pushed down into
`libnixcmd`, which is a lot less bad a place for this sort of thing.

.editorconfig

@@ -4,20 +4,20 @@
 # Top-most EditorConfig file
 root = true
 
-# Unix-style newlines with a newline ending every file, utf-8 charset
+# Unix-style newlines with a newline ending every file, UTF-8 charset
 [*]
 end_of_line = lf
 insert_final_newline = true
 trim_trailing_whitespace = true
 charset = utf-8
 
-# Match nix files, set indent to spaces with width of two
+# Match Nix files, set indent to spaces with width of two
 [*.nix]
 indent_style = space
 indent_size = 2
 
-# Match c++/shell/perl, set indent to spaces with width of four
+# Match C++/C/shell/Perl, set indent to spaces with width of four
-[*.{hpp,cc,hh,sh,pl,xs}]
+[*.{hpp,cc,hh,c,h,sh,pl,xs}]
 indent_style = space
 indent_size = 4
 

src/libcmd/command.cc

@@ -126,13 +126,11 @@ ref<EvalState> EvalCommand::getEvalState()
 {
     if (!evalState) {
         evalState =
+            std::allocate_shared<EvalState>(
             #if HAVE_BOEHMGC
-            std::allocate_shared<EvalState>(traceable_allocator<EvalState>(),
+                traceable_allocator<EvalState>(),
-                lookupPath, getEvalStore(), getStore())
-            #else
-            std::make_shared<EvalState>(
-                lookupPath, getEvalStore(), getStore())
             #endif
+                lookupPath, getEvalStore(), evalSettings, getStore())
             ;
 
         evalState->repair = repair;

src/libcmd/common-eval-args.cc

@@ -1,6 +1,7 @@
 #include "eval-settings.hh"
 #include "common-eval-args.hh"
 #include "shared.hh"
+#include "config-global.hh"
 #include "filetransfer.hh"
 #include "eval.hh"
 #include "fetchers.hh"
@@ -13,6 +14,12 @@
 
 namespace nix {
 
+EvalSettings evalSettings {
+    settings.readOnlyMode
+};
+
+static GlobalConfig::Register rEvalSettings(&evalSettings);
+
 MixEvalArgs::MixEvalArgs()
 {
     addFlag({

src/libcmd/common-eval-args.hh

@@ -12,9 +12,15 @@ namespace nix {
 
 class Store;
 class EvalState;
+struct EvalSettings;
 class Bindings;
 struct SourcePath;
 
+/**
+ * @todo Get rid of global setttings variables
+ */
+extern EvalSettings evalSettings;
+
 struct MixEvalArgs : virtual Args, virtual MixRepair
 {
     static constexpr auto category = "Common evaluation options";

src/libexpr-c/nix_api_expr.cc

@@ -7,6 +7,7 @@
 #include "eval.hh"
 #include "globals.hh"
 #include "util.hh"
+#include "eval-settings.hh"
 
 #include "nix_api_expr.h"
 #include "nix_api_expr_internal.h"
@@ -106,7 +107,21 @@ EvalState * nix_state_create(nix_c_context * context, const char ** lookupPath_c
             for (size_t i = 0; lookupPath_c[i] != nullptr; i++)
                 lookupPath.push_back(lookupPath_c[i]);
 
-        return new EvalState{nix::EvalState(nix::LookupPath::parse(lookupPath), store->ptr)};
+        void * p = ::operator new(
+            sizeof(EvalState),
+            static_cast<std::align_val_t>(alignof(EvalState)));
+        auto * p2 = static_cast<EvalState *>(p);
+        new (p) EvalState {
+            .settings = nix::EvalSettings{
+                nix::settings.readOnlyMode,
+            },
+            .state = nix::EvalState(
+                nix::LookupPath::parse(lookupPath),
+                store->ptr,
+                p2->settings),
+        };
+        loadConfFile(p2->settings);
+        return p2;
     }
     NIXC_CATCH_ERRS_NULL
 }

src/libexpr-c/nix_api_expr_internal.h

@@ -2,11 +2,13 @@
 #define NIX_API_EXPR_INTERNAL_H
 
 #include "eval.hh"
+#include "eval-settings.hh"
 #include "attr-set.hh"
 #include "nix_api_value.h"
 
 struct EvalState
 {
+    nix::EvalSettings settings;
     nix::EvalState state;
 };
 

src/libexpr/eval-settings.cc

@@ -45,7 +45,8 @@ static Strings parseNixPath(const std::string & s)
     return res;
 }
 
-EvalSettings::EvalSettings()
+EvalSettings::EvalSettings(bool & readOnlyMode)
+    : readOnlyMode{readOnlyMode}
 {
     auto var = getEnv("NIX_PATH");
     if (var) nixPath = parseNixPath(*var);
@@ -55,7 +56,7 @@ EvalSettings::EvalSettings()
         builtinsAbortOnWarn = true;
 }
 
-Strings EvalSettings::getDefaultNixPath()
+Strings EvalSettings::getDefaultNixPath() const
 {
     Strings res;
     auto add = [&](const Path & p, const std::string & s = std::string()) {
@@ -68,7 +69,7 @@ Strings EvalSettings::getDefaultNixPath()
         }
     };
 
-    if (!evalSettings.restrictEval && !evalSettings.pureEval) {
+    if (!restrictEval && !pureEval) {
         add(getNixDefExpr() + "/channels");
         add(rootChannelsDir() + "/nixpkgs", "nixpkgs");
         add(rootChannelsDir());
@@ -94,16 +95,12 @@ std::string EvalSettings::resolvePseudoUrl(std::string_view url)
         return std::string(url);
 }
 
-const std::string & EvalSettings::getCurrentSystem()
+const std::string & EvalSettings::getCurrentSystem() const
 {
     const auto & evalSystem = currentSystem.get();
     return evalSystem != "" ? evalSystem : settings.thisSystem.get();
 }
 
-EvalSettings evalSettings;
-
-static GlobalConfig::Register rEvalSettings(&evalSettings);
-
 Path getNixDefExpr()
 {
     return settings.useXDGBaseDirectories

src/libexpr/eval-settings.hh

@@ -7,9 +7,11 @@ namespace nix {
 
 struct EvalSettings : Config
 {
-    EvalSettings();
+    EvalSettings(bool & readOnlyMode);
 
-    static Strings getDefaultNixPath();
+    bool & readOnlyMode;
+
+    Strings getDefaultNixPath() const;
 
     static bool isPseudoUrl(std::string_view s);
 
@@ -74,7 +76,7 @@ struct EvalSettings : Config
      * Implements the `eval-system` vs `system` defaulting logic
      * described for `eval-system`.
      */
-    const std::string & getCurrentSystem();
+    const std::string & getCurrentSystem() const;
 
     Setting<bool> restrictEval{
         this, false, "restrict-eval",
@@ -193,8 +195,6 @@ struct EvalSettings : Config
         )"};
 };
 
-extern EvalSettings evalSettings;
-
 /**
  * Conventionally part of the default nix path in impure mode.
  */

src/libexpr/eval.cc

@@ -9,7 +9,6 @@
 #include "store-api.hh"
 #include "derivations.hh"
 #include "downstream-placeholder.hh"
-#include "globals.hh"
 #include "eval-inline.hh"
 #include "filetransfer.hh"
 #include "function-trace.hh"
@@ -219,8 +218,10 @@ static constexpr size_t BASE_ENV_SIZE = 128;
 EvalState::EvalState(
     const LookupPath & _lookupPath,
     ref<Store> store,
+    const EvalSettings & settings,
     std::shared_ptr<Store> buildStore)
-    : sWith(symbols.create("<with>"))
+    : settings{settings}
+    , sWith(symbols.create("<with>"))
     , sOutPath(symbols.create("outPath"))
     , sDrvPath(symbols.create("drvPath"))
     , sType(symbols.create("type"))
@@ -276,10 +277,10 @@ EvalState::EvalState(
     , repair(NoRepair)
     , emptyBindings(0)
     , rootFS(
-        evalSettings.restrictEval || evalSettings.pureEval
+        settings.restrictEval || settings.pureEval
         ? ref<SourceAccessor>(AllowListSourceAccessor::create(getFSSourceAccessor(), {},
-            [](const CanonPath & path) -> RestrictedPathError {
+            [&settings](const CanonPath & path) -> RestrictedPathError {
-                auto modeInformation = evalSettings.pureEval
+                auto modeInformation = settings.pureEval
                     ? "in pure evaluation mode (use '--impure' to override)"
                     : "in restricted mode";
                 throw RestrictedPathError("access to absolute path '%1%' is forbidden %2%", path, modeInformation);
@@ -330,10 +331,10 @@ EvalState::EvalState(
     vStringUnknown.mkString("unknown");
 
     /* Initialise the Nix expression search path. */
-    if (!evalSettings.pureEval) {
+    if (!settings.pureEval) {
         for (auto & i : _lookupPath.elements)
             lookupPath.elements.emplace_back(LookupPath::Elem {i});
-        for (auto & i : evalSettings.nixPath.get())
+        for (auto & i : settings.nixPath.get())
             lookupPath.elements.emplace_back(LookupPath::Elem::parse(i));
     }
 
@@ -411,9 +412,9 @@ bool isAllowedURI(std::string_view uri, const Strings & allowedUris)
 
 void EvalState::checkURI(const std::string & uri)
 {
-    if (!evalSettings.restrictEval) return;
+    if (!settings.restrictEval) return;
 
-    if (isAllowedURI(uri, evalSettings.allowedUris.get())) return;
+    if (isAllowedURI(uri, settings.allowedUris.get())) return;
 
     /* If the URI is a path, then check it against allowedPaths as
        well. */
@@ -458,7 +459,7 @@ void EvalState::addConstant(const std::string & name, Value * v, Constant info)
 
     constantInfos.push_back({name2, info});
 
-    if (!(evalSettings.pureEval && info.impureOnly)) {
+    if (!(settings.pureEval && info.impureOnly)) {
         /* Check the type, if possible.
 
            We might know the type of a thunk in advance, so be allowed
@@ -1413,11 +1414,11 @@ public:
 
 void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value & vRes, const PosIdx pos)
 {
-    if (callDepth > evalSettings.maxCallDepth)
+    if (callDepth > settings.maxCallDepth)
         error<EvalError>("stack overflow; max-call-depth exceeded").atPos(pos).debugThrow();
     CallDepth _level(callDepth);
 
-    auto trace = evalSettings.traceFunctionCalls
+    auto trace = settings.traceFunctionCalls
         ? std::make_unique<FunctionCallTrace>(positions[pos])
         : nullptr;
 
@@ -2745,7 +2746,7 @@ SourcePath EvalState::findFile(const LookupPath & lookupPath, const std::string_
         return {corepkgsFS, CanonPath(path.substr(3))};
 
     error<ThrownError>(
-        evalSettings.pureEval
+        settings.pureEval
             ? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
             : "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
         path
@@ -2825,7 +2826,7 @@ Expr * EvalState::parse(
     const SourcePath & basePath,
     std::shared_ptr<StaticEnv> & staticEnv)
 {
-    auto result = parseExprFromBuf(text, length, origin, basePath, symbols, positions, rootFS, exprSymbols);
+    auto result = parseExprFromBuf(text, length, origin, basePath, symbols, settings, positions, rootFS, exprSymbols);
 
     result->bindVars(*this, staticEnv);
 

src/libexpr/eval.hh

@@ -30,6 +30,7 @@ namespace nix {
 constexpr size_t maxPrimOpArity = 8;
 
 class Store;
+struct EvalSettings;
 class EvalState;
 class StorePath;
 struct SingleDerivedPath;
@@ -39,7 +40,6 @@ namespace eval_cache {
     class EvalCache;
 }
 
-
 /**
  * Function that implements a primop.
  */
@@ -162,6 +162,7 @@ struct DebugTrace {
 class EvalState : public std::enable_shared_from_this<EvalState>
 {
 public:
+    const EvalSettings & settings;
     SymbolTable symbols;
     PosTable positions;
 
@@ -352,6 +353,7 @@ public:
     EvalState(
         const LookupPath & _lookupPath,
         ref<Store> store,
+        const EvalSettings & settings,
         std::shared_ptr<Store> buildStore = nullptr);
     ~EvalState();
 

src/libexpr/flake/config.cc

@@ -1,6 +1,5 @@
 #include "users.hh"
 #include "config-global.hh"
-#include "globals.hh"
 #include "fetch-settings.hh"
 #include "flake.hh"
 

src/libexpr/flake/flake.cc

@@ -803,7 +803,7 @@ static void prim_getFlake(EvalState & state, const PosIdx pos, Value * * args, V
 {
     std::string flakeRefS(state.forceStringNoCtx(*args[0], pos, "while evaluating the argument passed to builtins.getFlake"));
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
-    if (evalSettings.pureEval && !flakeRef.input.isLocked())
+    if (state.settings.pureEval && !flakeRef.input.isLocked())
         throw Error("cannot call 'getFlake' on unlocked flake reference '%s', at %s (use --impure to override)", flakeRefS, state.positions[pos]);
 
     callFlake(state,
@@ -811,8 +811,8 @@ static void prim_getFlake(EvalState & state, const PosIdx pos, Value * * args, V
             LockFlags {
                 .updateLockFile = false,
                 .writeLockFile = false,
-                .useRegistries = !evalSettings.pureEval && fetchSettings.useRegistries,
+                .useRegistries = !state.settings.pureEval && fetchSettings.useRegistries,
-                .allowUnlocked = !evalSettings.pureEval,
+                .allowUnlocked = !state.settings.pureEval,
             }),
         v);
 }

src/libexpr/parser-state.hh

@@ -46,6 +46,7 @@ struct ParserState
     PosTable::Origin origin;
     const ref<SourceAccessor> rootFS;
     const Expr::AstSymbols & s;
+    const EvalSettings & settings;
 
     void dupAttr(const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos);
     void dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos);

src/libexpr/parser.y

@@ -25,7 +25,6 @@
 #include "nixexpr.hh"
 #include "eval.hh"
 #include "eval-settings.hh"
-#include "globals.hh"
 #include "parser-state.hh"
 
 #define YYLTYPE ::nix::ParserLocation
@@ -40,6 +39,7 @@ Expr * parseExprFromBuf(
     Pos::Origin origin,
     const SourcePath & basePath,
     SymbolTable & symbols,
+    const EvalSettings & settings,
     PosTable & positions,
     const ref<SourceAccessor> rootFS,
     const Expr::AstSymbols & astSymbols);
@@ -294,7 +294,7 @@ path_start
     $$ = new ExprPath(ref<SourceAccessor>(state->rootFS), std::move(path));
   }
   | HPATH {
-    if (evalSettings.pureEval) {
+    if (state->settings.pureEval) {
         throw Error(
             "the path '%s' can not be resolved in pure mode",
             std::string_view($1.p, $1.l)
@@ -429,6 +429,7 @@ Expr * parseExprFromBuf(
     Pos::Origin origin,
     const SourcePath & basePath,
     SymbolTable & symbols,
+    const EvalSettings & settings,
     PosTable & positions,
     const ref<SourceAccessor> rootFS,
     const Expr::AstSymbols & astSymbols)
@@ -441,6 +442,7 @@ Expr * parseExprFromBuf(
         .origin = positions.addOrigin(origin, length),
         .rootFS = rootFS,
         .s = astSymbols,
+        .settings = settings,
     };
 
     yylex_init(&scanner);

src/libexpr/primops.cc

@@ -5,7 +5,6 @@
 #include "eval.hh"
 #include "eval-settings.hh"
 #include "gc-small-vector.hh"
-#include "globals.hh"
 #include "json-to-value.hh"
 #include "names.hh"
 #include "path-references.hh"
@@ -78,7 +77,7 @@ StringMap EvalState::realiseContext(const NixStringContext & context, StorePathS
 
     if (drvs.empty()) return {};
 
-    if (isIFD && !evalSettings.enableImportFromDerivation)
+    if (isIFD && !settings.enableImportFromDerivation)
         error<EvalError>(
             "cannot build '%1%' during evaluation because the option 'allow-import-from-derivation' is disabled",
             drvs.begin()->to_string(*store)
@@ -901,7 +900,7 @@ static void prim_tryEval(EvalState & state, const PosIdx pos, Value * * args, Va
     MaintainCount trylevel(state.trylevel);
 
     ReplExitStatus (* savedDebugRepl)(ref<EvalState> es, const ValMap & extraEnv) = nullptr;
-    if (state.debugRepl && evalSettings.ignoreExceptionsDuringTry)
+    if (state.debugRepl && state.settings.ignoreExceptionsDuringTry)
     {
         /* to prevent starting the repl from exceptions withing a tryEval, null it. */
         savedDebugRepl = state.debugRepl;
@@ -950,7 +949,7 @@ static RegisterPrimOp primop_tryEval({
 static void prim_getEnv(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
     std::string name(state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.getEnv"));
-    v.mkString(evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
+    v.mkString(state.settings.restrictEval || state.settings.pureEval ? "" : getEnv(name).value_or(""));
 }
 
 static RegisterPrimOp primop_getEnv({
@@ -1017,7 +1016,7 @@ static void prim_trace(EvalState & state, const PosIdx pos, Value * * args, Valu
         printError("trace: %1%", args[0]->string_view());
     else
         printError("trace: %1%", ValuePrinter(state, *args[0]));
-    if (evalSettings.builtinsTraceDebugger) {
+    if (state.settings.builtinsTraceDebugger) {
         state.runDebugRepl(nullptr);
     }
     state.forceValue(*args[1], pos);
@@ -1056,11 +1055,11 @@ static void prim_warn(EvalState & state, const PosIdx pos, Value * * args, Value
         logWarning(info);
     }
 
-    if (evalSettings.builtinsAbortOnWarn) {
+    if (state.settings.builtinsAbortOnWarn) {
         // Not an EvalError or subclass, which would cause the error to be stored in the eval cache.
         state.error<EvalBaseError>("aborting to reveal stack trace of warning, as abort-on-warn is set").setIsFromExpr().debugThrow();
     }
-    if (evalSettings.builtinsTraceDebugger || evalSettings.builtinsDebuggerOnWarn) {
+    if (state.settings.builtinsTraceDebugger || state.settings.builtinsDebuggerOnWarn) {
         state.runDebugRepl(nullptr);
     }
     state.forceValue(*args[1], pos);
@@ -1578,7 +1577,7 @@ static RegisterPrimOp primop_toPath({
    corner cases. */
 static void prim_storePath(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    if (evalSettings.pureEval)
+    if (state.settings.pureEval)
         state.error<EvalError>(
             "'%s' is not allowed in pure evaluation mode",
             "builtins.storePath"
@@ -4562,7 +4561,7 @@ void EvalState::createBaseEnv()
         )",
     });
 
-    if (!evalSettings.pureEval) {
+    if (!settings.pureEval) {
         v.mkInt(time(0));
     }
     addConstant("__currentTime", v, {
@@ -4589,8 +4588,8 @@ void EvalState::createBaseEnv()
         .impureOnly = true,
     });
 
-    if (!evalSettings.pureEval)
+    if (!settings.pureEval)
-        v.mkString(evalSettings.getCurrentSystem());
+        v.mkString(settings.getCurrentSystem());
     addConstant("__currentSystem", v, {
         .type = nString,
         .doc = R"(
@@ -4670,7 +4669,7 @@ void EvalState::createBaseEnv()
 
 #ifndef _WIN32 // TODO implement on Windows
     // Miscellaneous
-    if (evalSettings.enableNativeCode) {
+    if (settings.enableNativeCode) {
         addPrimOp({
             .name = "__importNative",
             .arity = 2,
@@ -4693,7 +4692,7 @@ void EvalState::createBaseEnv()
           error if `--trace-verbose` is enabled. Then return *e2*. This function
           is useful for debugging.
         )",
-        .fun = evalSettings.traceVerbose ? prim_trace : prim_second,
+        .fun = settings.traceVerbose ? prim_trace : prim_second,
     });
 
     /* Add a value containing the current Nix expression search path. */

src/libexpr/primops/fetchMercurial.cc

@@ -53,7 +53,7 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
     // whitelist. Ah well.
     state.checkURI(url);
 
-    if (evalSettings.pureEval && !rev)
+    if (state.settings.pureEval && !rev)
         throw Error("in pure evaluation mode, 'fetchMercurial' requires a Mercurial revision");
 
     fetchers::Attrs attrs;

src/libexpr/primops/fetchTree.cc

@@ -171,10 +171,10 @@ static void fetchTree(
         }
     }
 
-    if (!evalSettings.pureEval && !input.isDirect() && experimentalFeatureSettings.isEnabled(Xp::Flakes))
+    if (!state.settings.pureEval && !input.isDirect() && experimentalFeatureSettings.isEnabled(Xp::Flakes))
         input = lookupInRegistries(state.store, input).first;
 
-    if (evalSettings.pureEval && !input.isLocked()) {
+    if (state.settings.pureEval && !input.isLocked()) {
         auto fetcher = "fetchTree";
         if (params.isFetchGit)
             fetcher = "fetchGit";
@@ -453,14 +453,14 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
         url = state.forceStringNoCtx(*args[0], pos, "while evaluating the url we should fetch");
 
     if (who == "fetchTarball")
-        url = evalSettings.resolvePseudoUrl(*url);
+        url = state.settings.resolvePseudoUrl(*url);
 
     state.checkURI(*url);
 
     if (name == "")
         name = baseNameOf(*url);
 
-    if (evalSettings.pureEval && !expectedHash)
+    if (state.settings.pureEval && !expectedHash)
         state.error<EvalError>("in pure evaluation mode, '%s' requires a 'sha256' argument", who).atPos(pos).debugThrow();
 
     // early exit if pinned and already in the store

src/nix-build/nix-build.cc

@@ -259,7 +259,7 @@ static void main_nix_build(int argc, char * * argv)
     auto store = openStore();
     auto evalStore = myArgs.evalStoreUrl ? openStore(*myArgs.evalStoreUrl) : store;
 
-    auto state = std::make_unique<EvalState>(myArgs.lookupPath, evalStore, store);
+    auto state = std::make_unique<EvalState>(myArgs.lookupPath, evalStore, evalSettings, store);
     state->repair = myArgs.repair;
     if (myArgs.repair) buildMode = bmRepair;
 

src/nix-env/nix-env.cc

@@ -1525,7 +1525,7 @@ static int main_nix_env(int argc, char * * argv)
 
         auto store = openStore();
 
-        globals.state = std::shared_ptr<EvalState>(new EvalState(myArgs.lookupPath, store));
+        globals.state = std::shared_ptr<EvalState>(new EvalState(myArgs.lookupPath, store, evalSettings));
         globals.state->repair = myArgs.repair;
 
         globals.instSource.nixExprPath = std::make_shared<SourcePath>(

src/nix-instantiate/nix-instantiate.cc

@@ -157,7 +157,7 @@ static int main_nix_instantiate(int argc, char * * argv)
         auto store = openStore();
         auto evalStore = myArgs.evalStoreUrl ? openStore(*myArgs.evalStoreUrl) : store;
 
-        auto state = std::make_unique<EvalState>(myArgs.lookupPath, evalStore, store);
+        auto state = std::make_unique<EvalState>(myArgs.lookupPath, evalStore, evalSettings, store);
         state->repair = myArgs.repair;
 
         Bindings & autoArgs = *myArgs.getAutoArgs(*state);

src/nix/main.cc

@@ -242,7 +242,7 @@ static void showHelp(std::vector<std::string> subcommand, NixArgs & toplevel)
 
     evalSettings.restrictEval = false;
     evalSettings.pureEval = false;
-    EvalState state({}, openStore("dummy://"));
+    EvalState state({}, openStore("dummy://"), evalSettings);
 
     auto vGenerateManpage = state.allocValue();
     state.eval(state.parseExprFromString(
@@ -418,7 +418,7 @@ void mainWrapped(int argc, char * * argv)
             Xp::FetchTree,
         };
         evalSettings.pureEval = false;
-        EvalState state({}, openStore("dummy://"));
+        EvalState state({}, openStore("dummy://"), evalSettings);
         auto res = nlohmann::json::object();
         res["builtins"] = ({
             auto builtinsJson = nlohmann::json::object();

src/nix/prefetch.cc

@@ -193,7 +193,7 @@ static int main_nix_prefetch_url(int argc, char * * argv)
           startProgressBar();
 
         auto store = openStore();
-        auto state = std::make_unique<EvalState>(myArgs.lookupPath, store);
+        auto state = std::make_unique<EvalState>(myArgs.lookupPath, store, evalSettings);
 
         Bindings & autoArgs = *myArgs.getAutoArgs(*state);
 

src/nix/upgrade-nix.cc

@@ -147,7 +147,7 @@ struct CmdUpgradeNix : MixDryRun, StoreCommand
         auto req = FileTransferRequest((std::string&) settings.upgradeNixStorePathUrl);
         auto res = getFileTransfer()->download(req);
 
-        auto state = std::make_unique<EvalState>(LookupPath{}, store);
+        auto state = std::make_unique<EvalState>(LookupPath{}, store, evalSettings);
         auto v = state->allocValue();
         state->eval(state->parseExprFromString(res.data, state->rootPath(CanonPath("/no-such-path"))), *v);
         Bindings & bindings(*state->allocBindings(0));

tests/unit/libexpr-support/tests/libexpr.hh

@@ -19,14 +19,14 @@ namespace nix {
             static void SetUpTestSuite() {
                 LibStoreTest::SetUpTestSuite();
                 initGC();
-                evalSettings.nixPath = {};
             }
 
         protected:
             LibExprTest()
                 : LibStoreTest()
-                , state({}, store)
+                , state({}, store, evalSettings, nullptr)
             {
+                evalSettings.nixPath = {};
             }
             Value eval(std::string input, bool forceValue = true) {
                 Value v;
@@ -42,6 +42,8 @@ namespace nix {
                 return state.symbols.create(value);
             }
 
+            bool readOnlyMode = true;
+            EvalSettings evalSettings{readOnlyMode};
             EvalState state;
     };