From 6e849e3b0a6eb46e6dc65cbd091cc829eab09a5f Mon Sep 17 00:00:00 2001
From: Bernardo Meurer <bernardo@meurer.org>
Date: Wed, 3 Mar 2021 14:46:15 -0800
Subject: [PATCH] nix-build: set execfail

When starting a nix-shell with `-i` it was previously possible for it to
silently fail in the scenario where the specified interpreter didn't
exist. This happened due to the `exec` call masking the issue.

With this change we enable `execfail`, which causes the script using
`nix-shell` as interpreter to correctly exit with code 127.

Fixes: #4598
---
 src/nix-build/nix-build.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 7b4a53919..65b85b304 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -447,6 +447,7 @@ static void main_nix_build(int argc, char * * argv)
                 "unset NIX_ENFORCE_PURITY; "
                 "shopt -u nullglob; "
                 "unset TZ; %6%"
+                "shopt -s execfail;"
                 "%7%",
                 shellEscape(tmpDir),
                 (pure ? "" : "p=$PATH; "),