secp256k1.h: clarify that by default arguments must be != NULL #926

1. 
   jonasnick commented at 5:02 pm on April 28, 2021: contributor

   The same file says that the illegal callback will only triger for violations explicitly mentioned, which is not true without this commit because we often don’t mention that an argument is not allowed to be NULL.

   This line is extracted from #783 in the hope that it gets merged faster because other PRs depend on it.

2. jonasnick cross-referenced this on Apr 28, 2021 from issue add `secp256k1_ec_pubkey_cmp` method by apoelstra
3. 
   gmaxwell commented at 10:42 pm on April 28, 2021: contributor

   This seems fine to me, though FWIW, calling any the non-nullable inputs with a statically null input will cause warnings in the caller. And the non-nullable arguments should all be documented as non-nullable with the annotations in the header (though not in doxygen, indeed).
4. jonasnick force-pushed on Apr 29, 2021
5. secp256k1.h: clarify that by default arguments must be != NULL

   The same file says that the illegal callback will only triger for violations
   explicitly mentioned, which is not true without this commit because we often
   don't mention that an argument is not allowed to be NULL.

   0881633dfd
6. 
   jonasnick commented at 10:22 am on April 29, 2021: contributor

   Agreed. Pushed an unrelated (slight) tweak.
7. real-or-random approved
8. 
   real-or-random commented at 10:29 am on April 29, 2021: contributor

   ACK 0881633dfd0c530a915cf63be295f00841c94cc4
9. real-or-random cross-referenced this on Apr 29, 2021 from issue Persistent worker failed to start the task: Parallels isolation failed by real-or-random
10. 
    gmaxwell commented at 4:35 pm on May 7, 2021: contributor

    ACK 0881633dfd0c530a915cf63be295f00841c94cc4
11. real-or-random merged this on May 7, 2021
12. real-or-random closed this on May 7, 2021

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13. jonasnick cross-referenced this on Jun 14, 2021 from issue Upstream PRs 831, 907, 903, 889, 918, 906, 928, 922, 933, Merge bitcoin-core/secp256k1#936: Fix gen_context/ASM build on ARM, 925, 937, 926, Merge bitcoin-core/secp256k1#940: contrib: Explain explicit header guards, 850, 930, 941, 846, 947, 662, 950 by jonasnick

Contributors
jonasnick gmaxwell real-or-random