From e1f308a1ec3c395cd4978b45400f7a45adcea0dc Mon Sep 17 00:00:00 2001
From: Tom Bereknyei <tomberek@gmail.com>
Date: Wed, 18 May 2022 22:28:15 -0400
Subject: [PATCH] repl: provide backward compat with legacy usage

---
 src/libcmd/command.hh |  2 +-
 src/nix/repl.cc       | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 65eb0c4a0..2c88e1526 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -120,7 +120,7 @@ struct InstallablesCommand : virtual Args, SourceExprCommand
 
     std::optional<FlakeRef> getFlakeRefForCompletion() override;
 
-private:
+protected:
 
     std::vector<std::string> _installables;
 };
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index cae76bb5d..d4079816f 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -895,6 +895,22 @@ struct CmdRepl : InstallablesCommand
     CmdRepl(){
         evalSettings.pureEval = false;
     }
+    void prepare()
+    {
+        if (!settings.isExperimentalFeatureEnabled(Xp::Flakes) && !(file)) {
+            warn("future versions of Nix will require using `--file` to load a file");
+            if (this->_installables.size() > 1) {
+                warn("more than one input file is not currently supported");
+            }
+            if (this->_installables.size() >= 1) {
+                file = std::optional(
+                    this->_installables[0].data()
+                );
+            }
+            _installables.clear();
+        }
+        installables = InstallablesCommand::load();
+    }
     std::vector<std::string> files;
     Strings getDefaultFlakeAttrPaths() override
     {