Re: EPICS base-3.15.9 fails to build with GCC-15

[NICOLE Rémi via Tech-talk <tech-talk at aps.anl.gov>]

Hello Dimitry, I had similar issues but manage to solve them with two
actions:

- Set `USR_CFLAGS="-std=c11"` in `configure/CONFIG_SITE.local`
- Apply the following commit that's on the 3.15 branch:
https://urldefense.us/v3/__https://github.com/epics-base/epics-base/commit/a509aa660d9f3ca3d2123fe16b89234065997fe6__;!!G_uCfscf7eWS!cnYQnLe4pIAGyKYVP23ScgodhnPDhZ5V_0JBalJJYIk4EKtvBXvJ2Io5UKRXjBLjjNJsYPPab7PBor53DdnK346Cow$ 

With this I can compile epics-base 3.15.9 with GCC 15.

Cheers!
-- 
Rémi NICOLE <remi.nicole at cea.fr>
CEA/DRF/IRFU/DIS/LDISC

On Tue, 2026-09-22 at 15:38 +0700, Dmitry Yu. Bolkhovityanov via Tech-
talk wrote:
> Hi!
> 
> GCC-14 becomes mainstream (e.g. Debian-13), and familiar base-3.15.6 
> fails to build with it.  Fotrunately, 3.15.9 was built successfully,
> but I 
> wanted to check it for "future-proofness" and tried building with
> GCC-15 
> and GCC-16.  It had failed with both.
> 
> The test was carried out on Debian-13/x86_64, gcc-15.3.0 and gcc-
> 16.2.0 
> built from sources and installed into /opt/.  The commandline is
> 
>  	make CC=/opt/gcc-15/bin/gcc CCC=/opt/gcc-15/bin/g++
> 
> and it results in error compiling src/libCom/flex/ccl.c:
> 
> 
> ../../../src/libCom/flex/ccl.c: In function 'list_character_set':
> ../../../src/libCom/flex/ccl.c:155:20: error: too many arguments to
> function 'readable_form'; expected 0, have 1
>    155 |             fputs( readable_form( i ), file );
>        |                    ^~~~~~~~~~~~~  ~
> ../../../src/libCom/flex/ccl.c:143:11: note: declared here
>    143 |     char *readable_form();
>        |           ^~~~~~~~~~~~~
> ../../../src/libCom/flex/ccl.c:162:39: error: too many arguments to
> function 'readable_form'; expected 0, have 1
>    162 |                 fprintf( file, "-%s", readable_form( i - 1 )
> );
>        |                                       ^~~~~~~~~~~~~  ~~~~~
> ../../../src/libCom/flex/ccl.c:143:11: note: declared here
>    143 |     char *readable_form();
>        |           ^~~~~~~~~~~~~
> 
> (gcc-16 produces the same result).
> 
> Old base-7.0.7 had failed in exactly the same way, while the most
> recent 
> base-7.0.10 had built successfully with both GCC-15 and GCC-16.
> (A quick inspection shows obvious fixes related to readable_form(),
> which 
> was previously incorrectly declared as "readable_form()" instead of 
> "readable_form(int c)".)
> 
> 
> The 3.15.9 is currently the latest release of EPICS3, which is still 
> widely used.  And there are chances it will become unbuildable on
> modern 
> systems in a year or two.
> 
> Maybe the time for base-3.15.10 had come?
> 
> 
> With best regards,
> Dmitry