Merge pull request #6027 from Ma27/pure-repl

repl: `--option pure-eval true` actually enables pure eval mode

src/libcmd/repl.cc

@@ -1039,6 +1039,11 @@ struct CmdRepl : StoreCommand, MixEvalArgs
         });
     }
 
+    bool forceImpureByDefault() override
+    {
+        return true;
+    }
+
     std::string description() override
     {
         return "start an interactive environment for evaluating Nix expressions";
@@ -1053,8 +1058,6 @@ struct CmdRepl : StoreCommand, MixEvalArgs
 
     void run(ref<Store> store) override
     {
-        evalSettings.pureEval = false;
-
         auto evalState = make_ref<EvalState>(searchPath, store);
 
         auto repl = std::make_unique<NixRepl>(evalState);

src/libutil/args.hh

@@ -25,6 +25,8 @@ public:
     /* Return a short one-line description of the command. */
     virtual std::string description() { return ""; }
 
+    virtual bool forceImpureByDefault() { return false; }
+
     /* Return documentation about this command, in Markdown format. */
     virtual std::string doc() { return ""; }
 

src/nix/main.cc

@@ -380,6 +380,9 @@ void mainWrapped(int argc, char * * argv)
         settings.ttlPositiveNarInfoCache = 0;
     }
 
+    if (args.command->second->forceImpureByDefault() && !evalSettings.pureEval.overridden) {
+        evalSettings.pureEval = false;
+    }
     args.command->second->prepare();
     args.command->second->run();
 }

tests/repl.sh

@@ -42,6 +42,11 @@ testRepl () {
     echo "$replOutput"
     echo "$replOutput" | grep -qs "while evaluating the file" \
       || fail "nix repl --show-trace doesn't show the trace"
+
+    nix repl "${nixArgs[@]}" --option pure-eval true 2>&1 <<< "builtins.currentSystem" \
+      | grep "attribute 'currentSystem' missing"
+    nix repl "${nixArgs[@]}" 2>&1 <<< "builtins.currentSystem" \
+      | grep "$(nix-instantiate --eval -E 'builtins.currentSystem')"
 }
 
 # Simple test, try building a drv