nixfmt[-rfc-style]: unstable -> 1.0.0

Also:
- Updates the update script to use stable versions going forward
- Make pkgs.nixfmt the -rfc-style version and remove the warning
- Create a (delayed) warning for the -rfc-style version to encourage
  switching to pkgs.nixfmt in a couple releases
- Add a release note for the above

doc/release-notes/rl-2511.section.md

@@ -8,6 +8,7 @@
   this release sets the default march level to `la64v1.0`, covering the desktop and server processors of 3X5000
   and newer series. However, embedded chips without LSX (Loongson SIMD eXtension), such as 2K0300 SoC, are not
   supported. `pkgsCross.loongarch64-linux-embedded` can be used to build software and systems for these platforms.
+- The official Nix formatter `nixfmt` is now stable and available as `pkgs.nixfmt`, deprecating the temporary `pkgs.nixfmt-rfc-style` attribute. The classic `nixfmt` will stay available for some more time as `pkgs.nixfmt-classic`.
 
 ## Backward Incompatibilities {#sec-nixpkgs-release-25.11-incompatibilities}
 

pkgs/by-name/ni/nixfmt-rfc-style/date.txt

@@ -1 +0,0 @@
-2025-04-04

pkgs/by-name/ni/nixfmt-rfc-style/update.sh

@@ -1,33 +0,0 @@
-#!/usr/bin/env nix-shell
-#!nix-shell -i bash -p cabal2nix curl jq
-#
-# This script will update the nixfmt-rfc-style derivation to the latest version using
-# cabal2nix.
-
-set -eo pipefail
-
-# This is the directory of this update.sh script.
-script_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
-
-derivation_file="${script_dir}/generated-package.nix"
-date_file="${script_dir}/date.txt"
-
-# This is the latest version of nixfmt-rfc-style branch on GitHub.
-new_version=$(curl --silent https://api.github.com/repos/nixos/nixfmt/git/refs/heads/master | jq '.object.sha' --raw-output)
-new_date=$(curl --silent https://api.github.com/repos/nixos/nixfmt/git/commits/"$new_version" | jq '.committer.date' --raw-output)
-
-echo "Updating nixfmt-rfc-style to version $new_date."
-echo "Running cabal2nix and outputting to ${derivation_file}..."
-
-cat > "$derivation_file" << EOF
-# This file has been autogenerate with cabal2nix.
-# Update via ./update.sh
-EOF
-
-cabal2nix --jailbreak \
-  "https://github.com/nixos/nixfmt/archive/${new_version}.tar.gz" \
-  >> "$derivation_file"
-
-date --date="$new_date" -I > "$date_file"
-
-echo "Finished."

pkgs/by-name/ni/nixfmt/generated-package.nix

@@ -23,10 +23,10 @@
 }:
 mkDerivation {
   pname = "nixfmt";
-  version = "0.6.0";
+  version = "1.0.0";
   src = fetchzip {
-    url = "https://github.com/nixos/nixfmt/archive/65af4b69133d19f534d97746c97c2d5b464f43b4.tar.gz";
-    sha256 = "0l0w3janvss1n1j7qkcml97zndm2jm2gbrzzs9d8l0ixnrw0cd5r";
+    url = "https://github.com/nixos/nixfmt/archive/v1.0.0.tar.gz";
+    sha256 = "0iy2p893b2b5y4mvhy0d62675a7nd8fc6jm9mr32v9h2baj9ii3p";
   };
   isLibrary = true;
   isExecutable = true;

pkgs/by-name/ni/nixfmt/package.nix

@@ -3,30 +3,22 @@
   haskellPackages,
   lib,
   runCommand,
-  nixfmt-rfc-style,
+  nixfmt,
 }:
 let
   inherit (haskell.lib.compose) overrideCabal justStaticExecutables;
 
-  overrides = rec {
-    version = "unstable-${lib.fileContents ./date.txt}";
-
+  overrides = {
     passthru.updateScript = ./update.sh;
 
     teams = [ lib.teams.formatter ];
 
-    preBuild = ''
-      echo -n 'nixpkgs-${version}' > .version
-    '';
-
     # These tests can be run with the following command.
     #
-    # $ nix-build -A nixfmt-rfc-style.tests
-    passthru.tests =
-      runCommand "nixfmt-rfc-style-tests" { nativeBuildInputs = [ nixfmt-rfc-style ]; }
-        ''
-          nixfmt --version > $out
-        '';
+    # $ nix-build -A nixfmt.tests
+    passthru.tests = runCommand "nixfmt-tests" { nativeBuildInputs = [ nixfmt ]; } ''
+      nixfmt --version > $out
+    '';
   };
   raw-pkg = haskellPackages.callPackage ./generated-package.nix { };
 in

pkgs/by-name/ni/nixfmt/update.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p cabal2nix curl jq
+#
+# This script will update the nixfmt derivation to the latest version using
+# cabal2nix.
+
+set -eo pipefail
+
+# This is the directory of this update.sh script.
+script_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+derivation_file="${script_dir}/generated-package.nix"
+
+release_tag=$(curl --silent https://api.github.com/repos/NixOS/nixfmt/releases/latest | jq '.tag_name' --raw-output)
+
+echo "Updating nixfmt to version $release_tag."
+echo "Running cabal2nix and outputting to ${derivation_file}..."
+
+cat > "$derivation_file" << EOF
+# This file has been autogenerate with cabal2nix.
+# Update via ./update.sh
+EOF
+
+cabal2nix --jailbreak \
+  "https://github.com/nixos/nixfmt/archive/${release_tag}.tar.gz" \
+  >> "$derivation_file"
+
+echo "Finished."

pkgs/top-level/aliases.nix

@@ -1412,7 +1412,13 @@ mapAliases {
   nixStable = nixVersions.stable; # Added 2022-01-24
   nixUnstable = throw "nixUnstable has been removed. For bleeding edge (Nix master, roughly weekly updated) use nixVersions.git, otherwise use nixVersions.latest."; # Converted to throw 2024-04-22
   nix_2_3 = nixVersions.nix_2_3;
-  nixfmt = lib.warnOnInstantiate "nixfmt was renamed to nixfmt-classic. The nixfmt attribute may be used for the new RFC 166-style formatter in the future, which is currently available as nixfmt-rfc-style" nixfmt-classic; # Added 2024-03-31
+  nixfmt-rfc-style =
+    if lib.oldestSupportedReleaseIsAtLeast 2511 then
+      lib.warnOnInstantiate
+        "nixfmt-rfc-style is now the same as pkgs.nixfmt which should be used instead."
+        nixfmt # Added 2025-07-14
+    else
+      nixfmt;
 
   # When the nixops_unstable alias is removed, nixops_unstable_minimal can be renamed to nixops_unstable.