From 159b5815b527f466578a2d28fbf832617cc45b88 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Mon, 31 Jan 2022 18:03:24 +0100
Subject: repl: `--option pure-eval true` actually enables pure eval mode

To quote Eelco in #5867:

> Unfortunately we can't do
>
>     evalSettings.pureEval.setDefault(false);
>
> because then we have to do the same in main.cc (where
> pureEval is set to true), and that would allow pure-eval
> to be disabled globally from nix.conf.

Instead, a command should specify that it should be impure by
default. Then, `evalSettings.pureEval` will be set to `false;` unless
it's overridden by e.g. a CLI flag.

In that case it's IMHO OK to be (theoretically) able to override
`pure-eval` via `nix.conf` because it doesn't have an effect on commands
where `forceImpureByDefault` returns `false` (i.e. everything where pure
eval actually matters).

Closes #5867
---
 src/nix/main.cc | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'src/nix/main.cc')

diff --git a/src/nix/main.cc b/src/nix/main.cc
index dadb54306..f398e3118 100644
--- a/src/nix/main.cc
+++ b/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();
 }
-- 
cgit v1.2.3