doc: include arg -DSECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS=ON for cmake #1790

1. 
   kevkevinpal commented at 3:18 am on December 19, 2025: contributor

   Motivation

   This is motivated by this comment #1778#pullrequestreview-3578687144

   Rationale

   It makes sense to add documentation on how to configure for CMake. I can reword if other wording is preferred

2. in include/secp256k1.h:353 in beaf41cd62

   348@@ -349,7 +349,8 @@ SECP256K1_API void secp256k1_context_destroy(
   349  *  writes the message to stderr and calls abort. This default callback can be
   350  *  replaced at link time if the preprocessor macro
   351  *  USE_EXTERNAL_DEFAULT_CALLBACKS is defined, which is the case if the build
   352- *  has been configured with --enable-external-default-callbacks. Then the
   353+ *  has been configured with --enable-external-default-callbacks or 
   354+ *  -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1. Then the
   

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   hebasto commented at 10:43 am on December 19, 2025:

   0 *  -DSECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS=ON. Then the
   

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   real-or-random commented at 2:42 pm on December 19, 2025:

   Maybe say “with –enable-external-default-callbacks (GNU Autotools) or -DSECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS=ON (CMake).”

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   kevkevinpal commented at 2:52 pm on December 19, 2025:

   Thanks! I updated to your suggestion in 0406cfc
3. real-or-random added the label user-documentation on Dec 19, 2025
4. real-or-random added the label tweak/refactor on Dec 19, 2025
5. doc: include arg -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1 for cmake 0406cfc4d1
6. kevkevinpal force-pushed on Dec 19, 2025
7. hebasto approved
8. 
   hebasto commented at 5:06 pm on December 19, 2025: member

   ACK 0406cfc4d1d414bbc806757bb42e540bf0d8a0c1.

   The PR title has to be updated as well.

9. kevkevinpal renamed this:
   doc: include arg -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1 for cmake
   doc: include arg -DSECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS=ON for cmake
   on Dec 19, 2025
10. real-or-random approved
11. 
    real-or-random commented at 7:50 pm on December 19, 2025: contributor

    ACK 0406cfc4d1d414bbc806757bb42e540bf0d8a0c1
12. real-or-random merged this on Dec 19, 2025
13. real-or-random closed this on Dec 19, 2025

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Contributors
kevkevinpal hebasto real-or-random

Labels
user-documentation tweak/refactor