From 12dd8d49c60186ae193fd96ef8904aa223ca7097 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Wed, 12 Oct 2022 21:51:36 +0200
Subject: [PATCH] Fix 'nix-instantiate --find-file' and add a test

Reported by @lheckemann.
---
 src/nix-instantiate/nix-instantiate.cc | 5 ++++-
 tests/nix_path.sh                      | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index fc3b4dae9..fc39c0827 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -169,7 +169,10 @@ static int main_nix_instantiate(int argc, char * * argv)
         if (findFile) {
             for (auto & i : files) {
                 auto p = state->findFile(i);
-                std::cout << p.readFile() << std::endl;
+                if (auto fn = p.getPhysicalPath())
+                    std::cout << fn->abs() << std::endl;
+                else
+                    throw Error("'%s' has no physical path", p);
             }
             return 0;
         }
diff --git a/tests/nix_path.sh b/tests/nix_path.sh
index d3657abf0..2b222b4a1 100644
--- a/tests/nix_path.sh
+++ b/tests/nix_path.sh
@@ -9,3 +9,6 @@ nix-instantiate --eval -E '<by-relative-path/simple.nix>' --restrict-eval
 
 # Should ideally also test this, but there’s no pure way to do it, so just trust me that it works
 # nix-instantiate --eval -E '<nixpkgs>' -I nixpkgs=channel:nixos-unstable --restrict-eval
+
+[[ $(nix-instantiate --find-file by-absolute-path/simple.nix) = $PWD/simple.nix ]]
+[[ $(nix-instantiate --find-file by-relative-path/simple.nix) = $PWD/simple.nix ]]