RFC: Generated headers with “"_hex user-defined literal #31861

1. 
   fjahr commented at 8:58 pm on February 13, 2025: contributor

   This is based on a suggestion by sipa in #28792.

   The generated header could be a lot smaller when using the “"_hex user-defined literal defined in util/strencodings.h. Primarily this would be nice for an embedded asmap file but since we already generate these headers it’s a conversation that doesn’t have to be tied to the asmap PR.

   I am looking for feedback on:

   • Do people take issue with including util/strencodings.h in the generated headers
   • I found that this doesn’t compile in my clang this doesn’t compile without bumping template depth and constexpr steps (I set -DAPPEND_CXXFLAGS='-ftemplate-depth=100000 -fconstexpr-steps=100000000' and didn’t try to find the cut-off point). We are dealing with data of up to 2MB, primarily the asmap file and the block we have in our test data. Would that be a dealbreaker for people?
2. WIP: raw data header with _hex 5fc3b82ab7
3. WIP: json header using _hex 91f9f95dcd
4. 
   DrahtBot commented at 8:59 pm on February 13, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/31861.

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5. 
   sipa commented at 9:59 pm on February 13, 2025: member

   Eh, needing -ftemplate-depth and -fconstexpr-steps sounds pretty terrible. Thank you for investigating, though.
6. 
   fjahr commented at 10:11 pm on February 13, 2025: contributor

   Alright, closing ✅
7. fjahr closed this on Feb 13, 2025

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