refactor: Remove useless extern keyword #21902

1. 
   MarcoFalke commented at 7:12 am on May 10, 2021: member

   It is redundant, confusing and useless.

   https://en.cppreference.com/w/cpp/language/storage_duration#external_linkage

2. refactor: Remove useless extern keyword fa4bbd306e
3. fanquake added the label Refactoring on May 10, 2021
4. 
   jonatack commented at 9:36 am on May 10, 2021: member

   Concept ACK, it’s confusing for me at least. There are more of these, but when they are before constants, mutexes, and functions (e.g. not for language linking) it’s not clear to me when they are needed.

   Light code review ACK fa4bbd306e1ca369d02eb864983fbb4d64b50ca9

5. 
   MarcoFalke commented at 10:02 am on May 10, 2021: member

   https://en.cppreference.com/w/cpp/language/storage_duration#external_linkage
6. 
   laanwj commented at 12:00 pm on May 10, 2021: member

   https://en.cppreference.com/w/cpp/language/storage_duration#external_linkage

   So basically: never use extern for functions, as they have external linkage by default, only for variables? This keeps coming back so it would be good to write it down in the developer notes.

7. 
   MarcoFalke commented at 12:08 pm on May 10, 2021: member

   This keeps coming back so it would be good to write it down in the developer notes.

   It seems all additions date back at least 5 years, so we didn’t have any issues with this recently. And it shouldn’t cause any harm. It is simply redundant. I’ll leave this as if for now, but I am happy to review a pull that adds this to the dev notes.

8. hebasto approved
9. 
   hebasto commented at 4:06 pm on May 10, 2021: member

   ACK fa4bbd306e1ca369d02eb864983fbb4d64b50ca9, I’ve verified that all of the remained extern keywords specify either (a) a variable with external linkage, or (b) a symbol with “C” language linkage.
10. 
    practicalswift commented at 6:05 pm on May 10, 2021: contributor

    cr ACK fa4bbd306e1ca369d02eb864983fbb4d64b50ca9: patch looks correct
11. 
    Talkless commented at 6:35 pm on May 10, 2021: none

    utACK fa4bbd306e1ca369d02eb864983fbb4d64b50ca9, built successfully on Debian Sid, looks OK.
12. 
    promag commented at 9:28 pm on May 10, 2021: member

    Code review ACK fa4bbd306e1ca369d02eb864983fbb4d64b50ca9.
13. fanquake merged this on May 10, 2021
14. fanquake closed this on May 10, 2021

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15. sidhujag referenced this in commit 071c0c6edb on May 11, 2021
16. MarcoFalke deleted the branch on May 11, 2021
17. gwillen referenced this in commit 9ea813efb8 on Jun 1, 2022
18. DrahtBot locked this on Aug 18, 2022

Contributors
MarcoFalke jonatack laanwj hebasto practicalswift Talkless promag

Labels
Refactoring