cmake: Improve and document compiler flag checks #1240

1. 
   hebasto commented at 11:17 pm on March 12, 2023: member

   This PR:

   • drops tinkering with the COMPILE_OPTIONS directory property in try_add_compile_option() and renames it to try_append_cflags()
   • copies related comments from configure.ac
2. hebasto cross-referenced this on Mar 19, 2023 from issue build: Add CMake-based build system (4 of N) by hebasto
3. hebasto force-pushed on Mar 22, 2023
4. hebasto cross-referenced this on Mar 22, 2023 from issue build: Meta-issue for follow-ups to initial CMake merge (#1113) by hebasto
5. real-or-random approved
6. 
   real-or-random commented at 8:36 am on March 26, 2023: contributor

   ACK 93f2ba0a4f7e576441eb5feb17e4cb3d178d37a3
7. hebasto force-pushed on Apr 27, 2023
8. 
   hebasto commented at 11:58 am on April 27, 2023: member

   Rebased.
9. cmake: Use `add_compile_options()` in `try_add_compile_option()`

   This change drops tinkering with the `COMPILE_OPTIONS` directory
   property. Also `try_add_compile_option()` can handle a list of flags
   now, if they are required to be checked simultaneously.
   
   An explanatory comments have been added as well.

   19516ed3e9
10. cmake, refactor: Rename `try_add_compile_option` to `try_append_cflags`

    Actually, `try_append_cflags()` can handle a list of flags, and the new
    name is similar to the one used in `configure.ac`.

    6ece1507cb
11. cmake, doc: Document compiler flags a8d059f76c
12. hebasto force-pushed on Apr 27, 2023
13. 
    theuni commented at 1:46 pm on April 27, 2023: contributor

    ACK https://github.com/bitcoin-core/secp256k1/pull/1240/commits/a8d059f76cb3429381adda1193c3d1976ba3cab4 .
14. real-or-random merged this on Apr 27, 2023
15. real-or-random closed this on Apr 27, 2023

    ---

16. hebasto deleted the branch on Apr 28, 2023
17. sipa referenced this in commit b4eb644b6c on May 12, 2023
18. hebasto referenced this in commit 49c52ea2b1 on May 13, 2023
19. vmta referenced this in commit e1120c94a1 on Jun 4, 2023
20. sipa referenced this in commit 901336eee7 on Jun 21, 2023
21. vmta referenced this in commit 8f03457eed on Jul 1, 2023
22. jonasnick cross-referenced this on Jul 24, 2023 from issue Upstream PRs 1268, 1276, 1267, 1265, 1230, 1279, 1273, 1263, 1231, 1285, 1283, 1205, 1286, 1275, 1234, 1239, 1240, 1284, 1277, 1289, 1270, 1296, 1301, 1299, 1066, 1300, 1292, 1305, 1303, 1133, 1306, 1207, 1304, 1307, 1311, 1309, 1312 by jonasnick

Contributors
hebasto real-or-random theuni