From 435df0ee5c67a3d3ad3aae1b18716748ae6cb4dc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 28 Feb 2025 14:39:14 +0100
Subject: [PATCH] nix flake pin: Mark the resulting registry entry as exact

Since the resulting target flakeref contains attributes like
"lastModified" or "narHash", it's not suitable for overriding. This
led to errors like

  $ nix build nixpkgs/24.05#hello
  error: 'lastModified' attribute mismatch in input 'github:NixOS/nixpkgs/63dacb46bf939521bdc93981b4cbb7ecb58427a0', expected 1728538411, got 1717179513

after doing `nix registry pin nixpkgs`.
---
 src/libfetchers/registry.cc | 8 +++++---
 src/libfetchers/registry.hh | 3 ++-
 src/nix/registry.cc         | 4 ++--
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/libfetchers/registry.cc b/src/libfetchers/registry.cc
index c18e12d2339..d2543c96a18 100644
--- a/src/libfetchers/registry.cc
+++ b/src/libfetchers/registry.cc
@@ -82,13 +82,15 @@ void Registry::write(const Path & path)
 void Registry::add(
     const Input & from,
     const Input & to,
-    const Attrs & extraAttrs)
+    const Attrs & extraAttrs,
+    bool exact)
 {
     entries.emplace_back(
         Entry {
             .from = from,
             .to = to,
-            .extraAttrs = extraAttrs
+            .extraAttrs = extraAttrs,
+            .exact = exact
         });
 }
 
@@ -142,7 +144,7 @@ void overrideRegistry(
     const Input & to,
     const Attrs & extraAttrs)
 {
-    getFlagRegistry(*from.settings)->add(from, to, extraAttrs);
+    getFlagRegistry(*from.settings)->add(from, to, extraAttrs, false);
 }
 
 static std::shared_ptr<Registry> getGlobalRegistry(const Settings & settings, ref<Store> store)
diff --git a/src/libfetchers/registry.hh b/src/libfetchers/registry.hh
index 8f47e15905e..fc29b8e6df0 100644
--- a/src/libfetchers/registry.hh
+++ b/src/libfetchers/registry.hh
@@ -45,7 +45,8 @@ struct Registry
     void add(
         const Input & from,
         const Input & to,
-        const Attrs & extraAttrs);
+        const Attrs & extraAttrs,
+        bool exact);
 
     void remove(const Input & input);
 };
diff --git a/src/nix/registry.cc b/src/nix/registry.cc
index ee45162302c..b5c8e0ad3f0 100644
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@@ -115,7 +115,7 @@ struct CmdRegistryAdd : MixEvalArgs, Command, RegistryCommand
         fetchers::Attrs extraAttrs;
         if (toRef.subdir != "") extraAttrs["dir"] = toRef.subdir;
         registry->remove(fromRef.input);
-        registry->add(fromRef.input, toRef.input, extraAttrs);
+        registry->add(fromRef.input, toRef.input, extraAttrs, false);
         registry->write(getRegistryPath());
     }
 };
@@ -193,7 +193,7 @@ struct CmdRegistryPin : RegistryCommand, EvalCommand
             warn("flake '%s' is not locked", resolved.to_string());
         fetchers::Attrs extraAttrs;
         if (ref.subdir != "") extraAttrs["dir"] = ref.subdir;
-        registry->add(ref.input, resolved, extraAttrs);
+        registry->add(ref.input, resolved, extraAttrs, true);
         registry->write(getRegistryPath());
     }
 };