An insuccessful attempt to package symbolica

Hello *,

symbolica (https://symbolica.io/) seems a very interesting computer 
algebra system. It is written in rust. I've never dealt with cargo-based 
ebuilds (and in general know not much about rust - just a little intro, 
hello world etc.). So, I used pycargoebuild to generate an ebuild, editted 
to to change SRC_URI to be

SRC_URI="
         https://github.com/${PN}-dev/${PN}/archive/refs/tags/v${PV}.tar.gz 
-> ${P}.tar.gz
         ${CARGO_CRATE_URIS}
"

edited HOMEPAGE, and tried to emerge this ebuild. After compiling a number 
of crates, it produced

error: failed to run custom build command for `gmp-mpfr-sys v1.7.1`

Caused by:
   process didn't exit successfully: 
`/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/symbolica-1.2.0/target/release/build/gmp-mpfr-sys-603c0efe0c06061c/build-script-build` 
(exit status: 101)
   --- stdout
   cargo:rerun-if-env-changed=GMP_MPFR_SYS_CACHE


   $ cd 
"/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/symbolica-1.2.0/target/release/build/gmp-mpfr-sys-d92d755b602760cc/out/build/gmp-build" 
&& "sh" "-c" "../gmp-src/configure --enable-fat --disable-shared 
--with-pic"
   checking build system type... alderlake-pc-linux-gnu
   checking host system type... alderlake-pc-linux-gnu
   checking for a BSD-compatible install... 
/usr/lib/portage/python3.14/ebuild-helpers/xattr/install -c
   checking whether build environment is sane... yes
   checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
   checking for gawk... gawk
   checking whether make sets $(MAKE)... yes
   checking whether make supports nested variables... yes
   checking whether to enable maintainer-specific portions of Makefiles... 
no

   --- stderr
   configure: error: ABI=amd64 is not among the following valid choices: 64 
x32 32

   thread 'main' (383) panicked at 
/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/cargo_home/gentoo/gmp-mpfr-sys-1.7.1/build.rs:1221:13:
   Program failed with code 1: cd 
"/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/symbolica-1.2.0/target/release/build/gmp-mpfr-sys-d92d755b602760cc/out/build/gmp-build" 
&& "sh" "-c" "../gmp-src/configure --enable-fat --disable-shared 
--with-pic"
   note: run with `RUST_BACKTRACE=1` environment variable to display a 
backtrace
warning: build failed, waiting for other jobs to finish...


The directory

localhost 
/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/cargo_home/gentoo/gmp-mpfr-sys-1.7.1 
# ls
Cargo.lock  Cargo.toml.orig  LICENSE-LGPL.md  RELEASES.md  doc-c 
gmp-6.3.0-c  mpfr-4.2.2-c
Cargo.toml  LICENSE-GPL.md   README.md        build.rs     etc 
mpc-1.4.1-c  src

seems to contain C sources of gmp, mpc, mpfr. Is it possible to convince 
cargo to use the system libraries, not to compile them anew? Also, if I

cd 
/var/tmp/portage/sci-mathematics/symbolica-1.2.0/work/cargo_home/gentoo/gmp-mpfr-sys-1.7.1/gmp-6.3.0-c

and do

./configure --enable-fat --disable-shared --with-pic

as the log says, I see that ./configure succeeds, not produces the error

configure: error: ABI=amd64 is not among the following valid choices: 64
x32 32

Any ideas how to proceed?

Thanks in advance,
Andrey