Difficulty understanding why an overlay does not work for a package in a NixOS configuration

jtojnar · November 17, 2023, 4:53pm

noto-fonts-emoji is an alias not used anywhere in NixOS any more:

NixOS/nixpkgs/blob/5d9be0d8e5a67798da27312df674931264167119/pkgs/top-level/aliases.nix#L636-L636


      
          noto-fonts-emoji = noto-fonts-color-emoji; # Added 2023-09-09

The attribute you are looking for is noto-fonts-color-emoji, which is used as the default emoji font on NixOS:

github.com

NixOS/nixpkgs/blob/5d9be0d8e5a67798da27312df674931264167119/nixos/modules/config/fonts/packages.nix#L40


      
              };
            };
          
          
  config = {
              fonts.packages = lib.mkIf cfg.enableDefaultPackages (with pkgs; [
                dejavu_fonts
                freefont_ttf
                gyre-fonts # TrueType substitutes for standard PostScript fonts
                liberation_ttf
                unifont
                noto-fonts-color-emoji
              ]);
            };
          }

But the proper way to disable installing it is using the fonts.enableDefaultPackages = false; NixOS option. Just replacing a package with null can break other packages that rely on it – for example, twitter-color-emoji copies the build system from noto-fonts-color-emoji, and deltachat-desktop wants the TTF file.