Tup

From the tup manual: "Tup is a file-based build system".

Known Issues

tup rebuilds too often

When using updater.full_dep, tup rebuilds the full project every time you reboot due to mtime changes in /run/current-system.

The solution is to always use tup via nix-shell --pure so that /run/current-system is not in PATH

Github issue: tup/#397

Another method that minimizes changes to PATH is to create symlinks to tools with Tup:

# Tuprules.tup - export a bang-rule that calls the Dhall interpreter
DHALL_LINK = $(TUP_CWD)/dhall
!dhall = | $(DHALL_LINK) |> $(DHALL_LINK)/bin/dhall |>

# Tupfile - build a symlink to the nixpkgs#dhall package 
include_rules
: |> nix build nixpkgs#dhall --out-link %o |> $(DHALL_LINK)

mount does not unmount

Tup can either not find fusermount OR the fusermount that tup finds is not setuid when using --pure.

Github issue: nixpkgs/#107516

There is no real solution to this other than 1. patching tup to use setuid fusermount 2. (maybe) setting tup as setuid.

pkg-config can not find my packages

When using nix-shell, pkg-config, and tup; pkg-config calls via tup do not find any packages.

You must add export lines to your tupfile that correspond to the variables set by NixOS pkg-config:

  export PKG_CONFIG_PATH
  export PKG_CONFIG_PATH_FOR_TARGET
  export PKG_CONFIG_FOR_TARGET

You also have to export NIX_PKG_CONFIG* variables, which can change based on platform:

 export NIX_PKG_CONFIG_WRAPPER_TARGET_TARGET_x86_64_unknown_linux_gnu

You can verify this by adding : |> pkg-config --list-all > %o |> pkg-list.txt into your Tupfile and seeing which libraries are available via pkg-config.

Flakes

A Tup rule must not use a flake that resides in the same tup project as the rule because the nix command can aggressively access files in the vicinity of flake.nix. The flake should be external to the tup project or it can be stored within the same repository but only on a different branch, which would then then be registered in the local nix flake registry.