From 4112dd1fc93c9ff03a5a4e8be773c45ebefbbd1f Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 25 Sep 2023 17:08:04 +0200
Subject: [PATCH 1/3] Mark fetchTree as stable

---
 doc/manual/src/release-notes/rl-next.md | 4 +++-
 src/libexpr/primops/fetchTree.cc        | 1 -
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 418c1187c..c905f445f 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -6,4 +6,6 @@
 
 - The experimental feature `repl-flake` is no longer needed, as its functionality is now part of the `flakes` experimental feature. To get the previous behavior, use the `--file/--expr` flags accordingly.
 
-- Introduce new flake installable syntax `flakeref#.attrPath` where the "." prefix denotes no searching of default attribute prefixes like `packages.<SYSTEM>` or `legacyPackages.<SYSTEM>`.
\ No newline at end of file
+- Introduce new flake installable syntax `flakeref#.attrPath` where the "." prefix denotes no searching of default attribute prefixes like `packages.<SYSTEM>` or `legacyPackages.<SYSTEM>`.
+
+- `builtins.fetchTree` is now marked as stable.
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 3d7a85047..0335e5f36 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -213,7 +213,6 @@ static RegisterPrimOp primop_fetchTree({
           ```
     )",
     .fun = prim_fetchTree,
-    .experimentalFeature = Xp::Flakes,
 });
 
 static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v,

From f62b5500ff96cc46e610da13dcf72c134935642d Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 17 Oct 2023 14:52:34 +0200
Subject: [PATCH 2/3] fetchTree: Require the flakes experimental feature for
 the URL syntax

---
 src/libexpr/primops/fetchTree.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 0335e5f36..3431ff013 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -148,6 +148,11 @@ static void fetchTree(
             attrs.emplace("url", fixGitURL(url));
             input = fetchers::Input::fromAttrs(std::move(attrs));
         } else {
+            if (!experimentalFeatureSettings.isEnabled(Xp::Flakes))
+                state.debugThrowLastTrace(EvalError({
+                    .msg = hintfmt("passing a string argument to 'fetchTree' requires the 'flakes' experimental feature"),
+                    .errPos = state.positions[pos]
+                }));
             input = fetchers::Input::fromURL(url);
         }
     }
@@ -180,6 +185,10 @@ static RegisterPrimOp primop_fetchTree({
       *input* must be a [flake reference](@docroot@/command-ref/new-cli/nix3-flake.md#flake-references), either in attribute set representation or in the URL-like syntax.
       The input should be "locked", that is, it should contain a commit hash or content hash unless impure evaluation (`--impure`) is enabled.
 
+      > **Note**
+      >
+      > The URL-like syntax requires the [`flakes` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-flakes) to be enabled.
+
       Here are some examples of how to use `fetchTree`:
 
       - Fetch a GitHub repository using the attribute set representation:

From 3470cd68c46334d9d2c55e890f7fe50fa9ebe35c Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 17 Oct 2023 14:57:29 +0200
Subject: [PATCH 3/3] Mark some fetchers as experimental

---
 src/libfetchers/github.cc | 5 +++++
 src/libfetchers/path.cc   | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/src/libfetchers/github.cc b/src/libfetchers/github.cc
index 291f457f0..6c5c792ec 100644
--- a/src/libfetchers/github.cc
+++ b/src/libfetchers/github.cc
@@ -223,6 +223,11 @@ struct GitArchiveInputScheme : InputScheme
 
         return {result.tree.storePath, input};
     }
+
+    std::optional<ExperimentalFeature> experimentalFeature() override
+    {
+        return Xp::Flakes;
+    }
 };
 
 struct GitHubInputScheme : GitArchiveInputScheme
diff --git a/src/libfetchers/path.cc b/src/libfetchers/path.cc
index 01f1be978..092975f5d 100644
--- a/src/libfetchers/path.cc
+++ b/src/libfetchers/path.cc
@@ -125,6 +125,11 @@ struct PathInputScheme : InputScheme
 
         return {std::move(*storePath), input};
     }
+
+    std::optional<ExperimentalFeature> experimentalFeature() override
+    {
+        return Xp::Flakes;
+    }
 };
 
 static auto rPathInputScheme = OnStartup([] { registerInputScheme(std::make_unique<PathInputScheme>()); });