stdenv: force unaliased rm in default fixup (avoids prompt)

[hraban]

Description of changes

When running genericBuild interactively from a nix-shell, a bare rm without -f will cause a prompt to the user if they have rm aliased to rm -i. This is a pretty common alias.

Same would hold for cp, mv, etc.

Obviously a pretty painful patch in terms of rebuilds... :/

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 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.

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[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/3694

[SuperSandro2000]

-f also hides errors. I think a proper solution would be to unalias common aliases.

[hraban]

This would also solve the problem with mv and cp not letting a -f override a -i 👍 But it'd have to be local to the function, because we can't suddenly turn off a alias rm='rm -i' in someone's dev shell

[SuperSandro2000]

I think we should rather remove all aliases in the beginning of genericBuild otherwise we could need to add \ to potentially many program executions and the cost of rebuilding stdenv everytime.

[hraban]

I tried to design a POC but it turns out to be surprisingly difficult to do this for a function sourced by an interactive shell.

test.sh:

foo () {
	echo foo
}

foo_subshell () (
	echo foo
)

foo_unalias () {
	unalias -a
	echo foo
}

foo_unalias_subshell () (
	unalias -a
	echo foo
)

foo_shopt () {
	shopt -u expand_aliases
	echo foo
	shopt -s expand_aliases
}

foo_shopt_subshell () (
	shopt -u expand_aliases
	echo foo
	shopt -s expand_aliases
)

Result:

$ alias echo="echo aliased"
$ source test.sh
$ foo
aliased foo
$ foo_subshell
aliased foo
$ foo_unalias
aliased foo
$ foo_unalias_subshell
aliased foo
$ foo_shopt
aliased foo
$ foo_shopt_subshell
aliased foo
$ echo hello
hello

Do you have any other ideas?

(Edit: I agree with your point btw, I just can't think of a nice way to do it :/ )