tectonic-unwrapped: fix build with icu 75

[bryango]

Fixes #392552.

I have found a way to cherry-pick the necessary patches from upstream's master. The patch has to be vendored due to some trivial whitespace differences that prevent it to apply directly. This is fixed by hand in the second commit (the first commit contains only the original, unmodified patch).

Build success: https://github.com/bryango/nix-build-action/actions/runs/14028664706/job/39271728385

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/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 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.

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[stephen-huan]

Works, except it seems texpresso needs to be updated.

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 392621

---

x86_64-linux

❌ 1 package failed to build:

• texpresso

✅ 2 packages built:

• tectonic
• tectonic-unwrapped

[bryango]

@stephen-huan Thank you very much for the review! I pushed a new version which saves us from vendoring the patch. Can you see if the newer version also works? I will look into the texpresso failure.

[stephen-huan]

Seems texpresso works now, nice.

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 392621

---

x86_64-linux

✅ 3 packages built:

• tectonic
• tectonic-unwrapped
• texpresso

[stephen-huan]

Works for me (see nixpkgs-review in #392621 (comment)).

As mentioned in #392552 (comment), it's 009de06 (#386191) which breaks it but this fix is probably even cleaner than trying to figure out the interaction with clang.

[doronbehar]

Diff LGTM. Well done on the investigation @bryango !