[Reduce-algebra-developers] Building Reduce with current GCC 15

[Jeff J. <tr...@po...>]

Greetings,

I'm not sure when the changes occurred, but there is some trouble using
current GCC 15 (tested with 15.0.1 20250228 / Red Hat 15.0.1-0 which is
distributed with Fedora 42 Beta and Fedora Rawhide).  This will be the
new stable GCC version released in the next month or so, so it probably
makes sense to get the fixes in now.

g++: error: unrecognized command-line option ‘-fconstexpr-steps=32000000’

The `-fconstexpr-steps` argument is not supported, and is a fatal error.
This happens when building in `csl/cslbase`.  It seems the current
incantation would be `-fconstexpr-ops-limit`.  I also was able to build
without this flag at all and didn't notice any excessive compilation
time, so it may no longer be strictly necessary.

The configure script should probably try to see if compiling using
`-fconstexpr-steps` or `-fconstexpr-ops-limit` limit actually works
before using it.

Tangentially related, trying to configure reduce to build with Clang
results in only some of the project actually building with Clang.
I configured with: `env CC=clang CXX=clang++ ./configure --with-csl
--with-clang` ... and at least `cslbase/flatten` was still being
built with g++.  I'll save the compilation output and look into this
more tonight.

--
Jeffrey H. Johnson
tr...@po...