stdenv: Allow changing the patch command

[Tom-Hubrecht]

Description of changes

The patch utility is not fully compatible with the diffs generated by
git, one missing feature is the renaming of files. As GitHub exports diffs
of a PR with renames, it means that those patches are not guaranteed to work
with patch.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.11 Release Notes (or backporting 23.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[tobim]

The commit message should provide a motivation and this addition needs to be documented.

[Tom-Hubrecht]

The commit message should provide a motivation and this addition needs to be documented.

It is now fixed.

[tobim]

The patch utility is not fully compatible with the diffs generated by git, one missing feature is the renaming of files.

If this was the case a lot of patches in the tree would not apply. Can you provide a source for this?

[Tom-Hubrecht]

If this was the case a lot of patches in the tree would not apply. Can you provide a source for this?

Sure, the PR that made me realize this was #250565 , when trying to apply https://github.com/NixOS/nixpkgs/pull/250565.patch , the file gatherer-Cargo.lock would not be created.

[tobim]

Sure, the PR that made me realize this was #250565 , when trying to apply https://github.com/NixOS/nixpkgs/pull/250565.patch , the file gatherer-Cargo.lock would not be created.

Why should a patch for nixpkgs itself be applied in stdenv?
The patch linked to applies fine for me:

> curl https://patch-diff.githubusercontent.com/raw/NixOS/nixpkgs/pull/250565.patch | 
patch -p1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 37372    0 37372    0     0  92274      0 --:--:-- --:--:-- --:--:-- 92276
patching file pkgs/applications/misc/mission-center/Cargo.lock
patching file pkgs/applications/misc/mission-center/default.nix
patching file pkgs/applications/misc/mission-center/gatherer-Cargo.lock (renamed from pkgs/applications/misc/mission-center/proxy-Cargo.lock)
> ls pkgs/applications/misc/mission-center/gatherer-Cargo.lock                        
pkgs/applications/misc/mission-center/gatherer-Cargo.lock

Is it possible that the patch in your PATH is not GNU patch?

[Tom-Hubrecht]

Sure, the PR that made me realize this was #250565 , when trying to apply 250565.patch , the file gatherer-Cargo.lock would not be created.

Why should a patch for nixpkgs itself be applied in stdenv? The patch linked to applies fine for me:

> curl https://patch-diff.githubusercontent.com/raw/NixOS/nixpkgs/pull/250565.patch | 
patch -p1
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 37372    0 37372    0     0  92274      0 --:--:-- --:--:-- --:--:-- 92276
patching file pkgs/applications/misc/mission-center/Cargo.lock
patching file pkgs/applications/misc/mission-center/default.nix
patching file pkgs/applications/misc/mission-center/gatherer-Cargo.lock (renamed from pkgs/applications/misc/mission-center/proxy-Cargo.lock)
> ls pkgs/applications/misc/mission-center/gatherer-Cargo.lock                        
pkgs/applications/misc/mission-center/gatherer-Cargo.lock

Is it possible that the patch in your PATH is not GNU patch?

Oh, I found the issue, the original patch applies fine for me as well if I get it with curl, (I do have gnupatch in the path), the real problem comes from pkgs.fetchpatch which removes the mentions of the renames, so this PR wouldn't help at all.

[tobim]

Ah, that is tracked in #32084. You can try to use fetchpatch2.