Horton

Re: Use -fvisibility=hidden for shared libraries

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Laurenz Albe <laurenz.albe@cybertec.at>, pgsql-hackers@postgresql.org
Date: 2022-07-18T07:05:16Z
Lists: pgsql-hackers 
Hi,

On 2022-07-17 14:54:48 -0400, Tom Lane wrote:
> Beyond that, I think this is committable.  We're not likely to learn much
> more about any potential issues except by exposing it to the buildfarm
> and developer usage.

Leaving egg on my face aside, seems to work well so far.

It looks like we might be missing out on benefiting from this on more
platforms - the test right now is in the gcc specific section of configure.ac,
but it looks like at least Intel's, sun's and AIX's compilers might all
support -fvisibility with the same syntax.

Given that that's just about all compilers we support using configure, perhaps
we should just move that out of the compiler specific section? Doesn't look
like there's much precedent for that so far...

Greetings,

Andres Freund

Commits

  1. Mark all symbols exported from extension libraries PGDLLEXPORT.

  2. Default to hidden visibility for extension libraries where possible

  3. Remove now superfluous declarations of dlsym()ed symbols.

  4. Add central declarations for dlsym()ed symbols