From e928c72cf9f8d1963df86b3a4a1da0b2a14380ec Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Feb 2023 14:16:49 +0100
Subject: [PATCH 1/2] Revert "Document default `nix-path` value"

This reverts commit dba9173a1d8cb1dd40e5922d009cb3a434e081c3.
---
 src/libexpr/eval.hh | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 2340ef67b..876a6ae0e 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -581,14 +581,7 @@ struct EvalSettings : Config
 
     Setting<Strings> nixPath{
         this, {}, "nix-path",
-        R"(
-          List of directories to be searched for `<...>` file references.
-
-          If [pure evaluation](#conf-pure-eval) is disabled,
-          this is initialised using the [`NIX_PATH`](@docroot@/command-ref/env-common.md#env-NIX_PATH)
-          environment variable, or, if it is unset and [restricted evaluation](#conf-restrict-eval)
-          is disabled, a default search path including the user's and `root`'s channels.
-        )"};
+        "List of directories to be searched for `<...>` file references."};
 
     Setting<bool> restrictEval{
         this, false, "restrict-eval",

From dd93c12c6a3ebf5b52fe7045d708ed10f6acd0dd Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 27 Feb 2023 15:11:36 +0100
Subject: [PATCH 2/2] Revert "getDefaultNixPath: actually respect
 `{restrict,pure}-eval`"

This reverts commit 1cba5984a68a489c4a56691032e4c87991c678f4.
---
 src/libexpr/eval.cc | 36 +++++++++++++++---------------------
 src/libexpr/eval.hh |  4 ++--
 tests/nix_path.sh   |  5 -----
 tests/restricted.sh |  3 ---
 4 files changed, 17 insertions(+), 31 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 3e37c7f60..21fc4d0fe 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -519,7 +519,6 @@ EvalState::EvalState(
     static_assert(sizeof(Env) <= 16, "environment must be <= 16 bytes");
 
     /* Initialise the Nix expression search path. */
-    evalSettings.nixPath.setDefault(evalSettings.getDefaultNixPath());
     if (!evalSettings.pureEval) {
         for (auto & i : _searchPath) addToSearchPath(i);
         for (auto & i : evalSettings.nixPath.get()) addToSearchPath(i);
@@ -2473,35 +2472,30 @@ std::ostream & operator << (std::ostream & str, const ExternalValueBase & v) {
 
 EvalSettings::EvalSettings()
 {
+    auto var = getEnv("NIX_PATH");
+    if (var) nixPath = parseNixPath(*var);
 }
 
-/* impure => NIX_PATH or a default path
- * restrict-eval => NIX_PATH
- * pure-eval => empty
- */
 Strings EvalSettings::getDefaultNixPath()
 {
-    if (pureEval)
-        return {};
-
-    auto var = getEnv("NIX_PATH");
-    if (var) {
-        return parseNixPath(*var);
-    } else if (restrictEval) {
-        return {};
-    } else {
-        Strings res;
-        auto add = [&](const Path & p, const std::optional<std::string> & s = std::nullopt) {
-            if (pathExists(p))
-                res.push_back(s ? *s + "=" + p : p);
-        };
+    Strings res;
+    auto add = [&](const Path & p, const std::string & s = std::string()) {
+        if (pathExists(p)) {
+            if (s.empty()) {
+                res.push_back(p);
+            } else {
+                res.push_back(s + "=" + p);
+            }
+        }
+    };
 
+    if (!evalSettings.restrictEval && !evalSettings.pureEval) {
         add(settings.useXDGBaseDirectories ? getStateDir() + "/nix/defexpr/channels" : getHome() + "/.nix-defexpr/channels");
         add(settings.nixStateDir + "/profiles/per-user/root/channels/nixpkgs", "nixpkgs");
         add(settings.nixStateDir + "/profiles/per-user/root/channels");
-
-        return res;
     }
+
+    return res;
 }
 
 bool EvalSettings::isPseudoUrl(std::string_view s)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 876a6ae0e..e4d5906bd 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -570,7 +570,7 @@ struct EvalSettings : Config
 {
     EvalSettings();
 
-    Strings getDefaultNixPath();
+    static Strings getDefaultNixPath();
 
     static bool isPseudoUrl(std::string_view s);
 
@@ -580,7 +580,7 @@ struct EvalSettings : Config
         "Whether builtin functions that allow executing native code should be enabled."};
 
     Setting<Strings> nixPath{
-        this, {}, "nix-path",
+        this, getDefaultNixPath(), "nix-path",
         "List of directories to be searched for `<...>` file references."};
 
     Setting<bool> restrictEval{
diff --git a/tests/nix_path.sh b/tests/nix_path.sh
index d16fb4bb2..2b222b4a1 100644
--- a/tests/nix_path.sh
+++ b/tests/nix_path.sh
@@ -12,8 +12,3 @@ nix-instantiate --eval -E '<by-relative-path/simple.nix>' --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 ]]
-
-unset NIX_PATH
-
-[[ $(nix-instantiate --option nix-path by-relative-path=. --find-file by-relative-path/simple.nix) = "$PWD/simple.nix" ]]
-[[ $(NIX_PATH= nix-instantiate --option nix-path by-relative-path=. --find-file by-relative-path/simple.nix) = "$PWD/simple.nix" ]]
diff --git a/tests/restricted.sh b/tests/restricted.sh
index 3b6ee2af1..9bd16cf51 100644
--- a/tests/restricted.sh
+++ b/tests/restricted.sh
@@ -17,9 +17,6 @@ nix-instantiate --restrict-eval --eval -E 'builtins.readDir ../src/nix-channel'
 (! nix-instantiate --restrict-eval --eval -E 'let __nixPath = [ { prefix = "foo"; path = ./.; } ]; in <foo>')
 nix-instantiate --restrict-eval --eval -E 'let __nixPath = [ { prefix = "foo"; path = ./.; } ]; in <foo>' -I src=.
 
-# no default NIX_PATH
-(unset NIX_PATH; ! nix-instantiate --restrict-eval --find-file .)
-
 p=$(nix eval --raw --expr "builtins.fetchurl file://$(pwd)/restricted.sh" --impure --restrict-eval --allowed-uris "file://$(pwd)")
 cmp $p restricted.sh