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Anon-E-moose
Watchman
Joined: 23 May 2008
Posts: 6170
Location: Dallas area
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 Posted: Thu May 14, 2020 12:30 pm Post subject: gcc10 compiling/linking problems |
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There seem to be several programs that won't compile without errors with the gcc-10 compiler, and the key is complaining during the linking phase about multiple definitions. These are mostly caused by default behavior of the compile changing, specifically the "common" flag.
From the release notes
| Code: | | GCC now defaults to -fno-common. As a result, global variable accesses are more efficient on various targets. In C, global variables with multiple tentative definitions now result in linker errors. With -fcommon such definitions are silently merged during linking. |
What this means is that if you have multiple definitions in your code, and the common flag is set, you'll get a linking error.
Two ways to get things to compile.
1. add the common flag to your CFLAGS, the makes the behavior similar to pre-gcc10 compilers OR use an "env" override of "common" per package.
2. fix the code to get rid of multiple definitions.
Note: There are other problems with some packages (who thought that the gcc version would be over a single digit  ) that need a code change.
Edit to add: changed no-common to common, *doh*
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UM780, 6.1 zen kernel, gcc 13, profile 17.0 (custom bare multilib), openrc, wayland
Last edited by Anon-E-moose on Thu May 28, 2020 10:40 am; edited 2 times in total |
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thumper
Guru
Joined: 06 Dec 2002
Posts: 554
Location: Venice FL
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| Posted: Thu May 28, 2020 1:55 am Post subject: |
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Don't you mean makes the behavior similar to pre-gcc10 compilers.
And gives linker errors for unfixed code, which is now the default.
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Anon-E-moose
Watchman
Joined: 23 May 2008
Posts: 6170
Location: Dallas area
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| Posted: Thu May 28, 2020 10:38 am Post subject: |
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Indeed, I wrote it backwards.
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UM780, 6.1 zen kernel, gcc 13, profile 17.0 (custom bare multilib), openrc, wayland |
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Chiitoo
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Location: Here and Away Again
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