From 8bfc251282e82f2d6ab717340af6444ca77fb243 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Fri, 25 Aug 2023 17:17:33 +0200
Subject: [PATCH 1/2] tests/lang/eval-okay-pathexists: Add cases

(cherry picked from commit d2e6cfa0750cb38ceef7dc0b8bb31cf3b0387e9c)
---
 tests/lang/eval-okay-pathexists.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/lang/eval-okay-pathexists.nix b/tests/lang/eval-okay-pathexists.nix
index 50c28ee0c..8eae37e70 100644
--- a/tests/lang/eval-okay-pathexists.nix
+++ b/tests/lang/eval-okay-pathexists.nix
@@ -1,4 +1,6 @@
-builtins.pathExists (builtins.toPath ./lib.nix)
+builtins.pathExists (./lib.nix)
+&& builtins.pathExists (builtins.toPath ./lib.nix)
+&& builtins.pathExists (builtins.toString ./lib.nix)
 && builtins.pathExists (builtins.toPath (builtins.toString ./lib.nix))
 && !builtins.pathExists (builtins.toPath (builtins.toString ./bla.nix))
 && builtins.pathExists ./lib.nix

From d52690279aee89c28af74ca619ae7755e776e1f3 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Fri, 25 Aug 2023 17:18:37 +0200
Subject: [PATCH 2/2] pathExists: isDir when endswith /

Fixes https://github.com/NixOS/nix/issues/8838

(cherry picked from commit 1e08e12d8138b09e6872cb498b723ade9ad71d68)
---
 src/libexpr/primops.cc              | 16 +++++++++++++---
 tests/lang/eval-okay-pathexists.nix |  1 +
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 7ff17b6ee..3b476b700 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1511,15 +1511,25 @@ static RegisterPrimOp primop_storePath({
 
 static void prim_pathExists(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
+    auto & arg = *args[0];
+
     /* We don’t check the path right now, because we don’t want to
        throw if the path isn’t allowed, but just return false (and we
        can’t just catch the exception here because we still want to
-       throw if something in the evaluation of `*args[0]` tries to
+       throw if something in the evaluation of `arg` tries to
        access an unauthorized path). */
-    auto path = realisePath(state, pos, *args[0], { .checkForPureEval = false });
+    auto path = realisePath(state, pos, arg, { .checkForPureEval = false });
+
+    /* SourcePath doesn't know about trailing slash. */
+    auto mustBeDir = arg.type() == nString && arg.str().ends_with("/");
 
     try {
-        v.mkBool(state.checkSourcePath(path).pathExists());
+        auto checked = state.checkSourcePath(path);
+        auto exists = checked.pathExists();
+        if (exists && mustBeDir) {
+            exists = checked.lstat().type == InputAccessor::tDirectory;
+        }
+        v.mkBool(exists);
     } catch (SysError & e) {
         /* Don't give away info from errors while canonicalising
            ‘path’ in restricted mode. */
diff --git a/tests/lang/eval-okay-pathexists.nix b/tests/lang/eval-okay-pathexists.nix
index 8eae37e70..e1246e370 100644
--- a/tests/lang/eval-okay-pathexists.nix
+++ b/tests/lang/eval-okay-pathexists.nix
@@ -1,6 +1,7 @@
 builtins.pathExists (./lib.nix)
 && builtins.pathExists (builtins.toPath ./lib.nix)
 && builtins.pathExists (builtins.toString ./lib.nix)
+&& !builtins.pathExists (builtins.toString ./lib.nix + "/")
 && builtins.pathExists (builtins.toPath (builtins.toString ./lib.nix))
 && !builtins.pathExists (builtins.toPath (builtins.toString ./bla.nix))
 && builtins.pathExists ./lib.nix