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most dev flake inputs flake=false #4294

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60aef07
flake/dev: devshell flake=false
mightyiam May 15, 2026
201631b
flake/dev: git-hooks flake=false
mightyiam May 15, 2026
0566e39
flake/dev: home-manager flake=false
mightyiam May 15, 2026
3b64bc6
flake/dev: nix-darwin flake=false
mightyiam May 16, 2026
27ab16a
flake/dev: treefmt-nix flake=false
mightyiam May 15, 2026
7b80211
flake/dev: flake-compat flake=false
mightyiam May 15, 2026
4d35f4d
flake/dev: comment about flake=false
mightyiam May 15, 2026
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2 changes: 1 addition & 1 deletion flake/dev/devshell.nix
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
{ lib, inputs, ... }:
{
imports = [
inputs.devshell.flakeModule
(inputs.devshell + "/flake-module.nix")
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@mightyiam mightyiam May 15, 2026

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Small price to pay?

];

perSystem =
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56 changes: 6 additions & 50 deletions flake/dev/flake.lock
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18 changes: 11 additions & 7 deletions flake/dev/flake.nix
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Original file line number Diff line number Diff line change
@@ -1,35 +1,39 @@
{
description = "Private inputs for development purposes. These are used by the top level flake in the `dev` partition, but do not appear in consumers' lock files.";

# Avoid `flake = true` when we do not need to evaluate flake outputs or fetch flake inputs.
# e.g. when we only import loose files.
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inputs = {
# NOTE: Use a different name to the root flake's inputs.nixpkgs to avoid shadowing it.
# NOTE: The only reason we specify a nixpkgs input at all here, is so the other inputs can follow it.
# TODO: Once nix 2.26 is more prevalent, follow the root flake's inputs using a "path:../.." input.
dev-nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

# flake-compat is used by the root `default.nix` to allow non-flake users to import nixvim
flake-compat.url = "github:NixOS/flake-compat";
flake-compat = {
url = "github:NixOS/flake-compat";
flake = false;
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@mightyiam mightyiam May 15, 2026

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As @MattSturgeon pointed, flake-compat instructs declaring it with flake=false in its readme.

};

# keep-sorted start block=yes newline_separated=yes
devshell = {
url = "github:numtide/devshell";
inputs.nixpkgs.follows = "dev-nixpkgs";
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@mightyiam mightyiam May 15, 2026

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followses be gone!

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@MattSturgeon MattSturgeon May 15, 2026

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I'm not entirely sold on flake = false being worth it just for eliminating transitive follows.

Imagine the scenario where an input changes its inputs without us noticing; if we pull it as a flake, then we get their new inputs transitively. If we don't, then things potentially break.

If the reason we can set flake = false is that we are explicitly only using a part of the project that is designed to be used without flake inputs, then that's fine and should probably be documented in a comment.

# Don't pull flake inputs or evaluate outputs.
# We exclusively use the flake-module file.
flake = false;

Or perhaps a top-level comment along the lines of:

# Avoid `flake = true` when we do not need to evaluate flake outputs or fetch flake inputs.
# e.g. when we only import loose files.

TL;DR a) consider whether we're setting flake = false for the right reasons b) consider whether flake = false is fragile and may miss future transitive dependencies c) document why we enable or disable flake in general or for specific inputs.

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@mightyiam mightyiam May 15, 2026

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I've added that single comment above the inputs attribute.

I've pointed out in this PR for each flake=false why it is okay.

I think that projects that expose truly loose files such as /flake-module.nix and /lib/default.nix are aware that users will use them and are not likely to turn them into functions that first take local context such as flake inputs. I prefer this risk over lockfile drift.

flake = false;
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Exposes a vanilla /flake-module.nix, so we're good.

};

git-hooks = {
url = "github:cachix/git-hooks.nix";
inputs.nixpkgs.follows = "dev-nixpkgs";
inputs.flake-compat.follows = "flake-compat";
flake = false;
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@mightyiam mightyiam May 15, 2026

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Exposes a vanilla /flake-module.nix, so we're good.

};

home-manager = {
url = "github:nix-community/home-manager";
inputs.nixpkgs.follows = "dev-nixpkgs";
flake = false;
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Provides a /lib/default.nix that takes { inherit lib; } so we're golden.

};

nix-darwin = {
url = "github:lnl7/nix-darwin";
inputs.nixpkgs.follows = "dev-nixpkgs";
flake = false;
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@mightyiam mightyiam May 15, 2026

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Provides a vanilla /eval-config.nix so we're golden.

};

nuschtosSearch = {
Expand All @@ -40,7 +44,7 @@

treefmt-nix = {
url = "github:numtide/treefmt-nix";
inputs.nixpkgs.follows = "dev-nixpkgs";
flake = false;
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Provides a vanilla /flake-module.nix so we're golden.

};

# keep-sorted end
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2 changes: 1 addition & 1 deletion flake/dev/fmt.nix
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
{ inputs, ... }:
{
imports = [
inputs.treefmt-nix.flakeModule
(inputs.treefmt-nix + "/flake-module.nix")
];

perSystem =
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2 changes: 1 addition & 1 deletion flake/dev/git-hooks.nix
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
{ inputs, ... }:
{
imports = [
inputs.git-hooks.flakeModule
(inputs.git-hooks + "/flake-module.nix")
];

perSystem =
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28 changes: 20 additions & 8 deletions tests/platforms/darwin.nix
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Original file line number Diff line number Diff line change
@@ -1,18 +1,30 @@
{
self,
system,
lib,
}:
self.inputs.nix-darwin.lib.darwinSystem {
let
darwinSystem = import (self.inputs.nix-darwin + "/eval-config.nix");
in
darwinSystem {
inherit lib;

modules = [
{
nixpkgs.hostPlatform = system;
(
{ config, ... }:
{
nixpkgs = {
source = self.inputs.nixpkgs;
hostPlatform = system;
};

programs.nixvim = {
enable = true;
};
programs.nixvim = {
enable = true;
};

system.stateVersion = 5;
}
system.stateVersion = config.system.maxStateVersion;
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}
)
self.nixDarwinModules.nixvim
];
}
6 changes: 3 additions & 3 deletions tests/platforms/hm-extra-files-byte-compiling.nix
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Original file line number Diff line number Diff line change
@@ -1,11 +1,11 @@
{
self,
pkgs,
lib,
}:
let
inherit (self.inputs.home-manager.lib)
homeManagerConfiguration
;
hmLib = import (self.inputs.home-manager + "/lib") { inherit lib; };
inherit (hmLib) homeManagerConfiguration;

config = {
home = {
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6 changes: 3 additions & 3 deletions tests/platforms/hm-submodule-merge.nix
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
{
self,
pkgs,
lib,
}:
# This test covers a user-reported regression where nixvim's submodule-option (programs.nixvim)
# cannot correctly merge options declared from the parent scope.
Expand All @@ -9,9 +10,8 @@
#
# To be clear, this is an upstream module system bug, this test validates our workaround.
let
inherit (self.inputs.home-manager.lib)
homeManagerConfiguration
;
hmLib = import (self.inputs.home-manager + "/lib") { inherit lib; };
inherit (hmLib) homeManagerConfiguration;

# This test module declares a nixvim option from a Home Manager module
# The module system will attempt an option-type merge on the `programs.nixvim` option,
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6 changes: 5 additions & 1 deletion tests/platforms/hm.nix
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Original file line number Diff line number Diff line change
@@ -1,8 +1,12 @@
{
self,
pkgs,
lib,
}:
self.inputs.home-manager.lib.homeManagerConfiguration {
let
hmLib = import (self.inputs.home-manager + "/lib") { inherit lib; };
in
hmLib.homeManagerConfiguration {
inherit pkgs;

modules = [
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