sci-mathematics/gap: fix C23 issues

Apply an upstream patch to change the declaration of ObjFunc from,

  typedef Obj (* ObjFunc) (/*arguments*/);

to,

  typedef void * ObjFunc;

in the public API. There is a corresponding subslot bump to rebuild
consumers. This fixes similar issues in dev-gap/{browse,edim}, and
dev-gap/datastructures-0.3.3 was fixed ahead of time.

Closes: https://bugs.gentoo.org/944036
Closes: https://bugs.gentoo.org/954796
Closes: https://bugs.gentoo.org/954798
Closes: https://bugs.gentoo.org/954803
Signed-off-by: Michael Orlitzky <mjo@gentoo.org>

sci-mathematics/gap/files/gap-4.14.0-objfunc-voidptr.patch

@@ -0,0 +1,27 @@
+From 084b8fb6e7273295cad3330e5c42b850c39c3175 Mon Sep 17 00:00:00 2001
+From: Jan Engelhardt <jengelh@inai.de>
+Date: Fri, 18 Jul 2025 01:23:34 +0200
+Subject: [PATCH] Fix build issues when compiling GAP with GCC 15 (#6010)
+
+---
+ src/common.h | 7 +------
+ 1 file changed, 1 insertion(+), 6 deletions(-)
+
+diff --git a/src/common.h b/src/common.h
+index 3932c3020b..02818f567c 100644
+--- a/src/common.h
++++ b/src/common.h
+@@ -161,12 +161,7 @@ typedef Bag Obj;
+ **
+ **  'ObjFunc' is the type of a function returning an object.
+ */
+-#pragma GCC diagnostic push
+-#ifndef __cplusplus
+-#pragma GCC diagnostic ignored "-Wstrict-prototypes"
+-#endif
+-typedef Obj (* ObjFunc) (/*arguments*/);
+-#pragma GCC diagnostic pop
++typedef void * ObjFunc;
+ 
+ typedef Obj (* ObjFunc_0ARGS) (Obj self);
+ typedef Obj (* ObjFunc_1ARGS) (Obj self, Obj a1);

sci-mathematics/gap/gap-4.14.0-r1.ebuild

@@ -0,0 +1,138 @@
+# Copyright 1999-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit estack
+
+DESCRIPTION="System for computational discrete algebra. Core functionality."
+HOMEPAGE="https://www.gap-system.org/"
+SRC_URI="https://github.com/gap-system/gap/releases/download/v${PV}/${P}-core.tar.gz"
+
+LICENSE="GPL-2+"
+SLOT="0/9voidptr" # soname
+KEYWORDS="~amd64 ~riscv"
+IUSE="cpu_flags_x86_popcnt debug memcheck minimal readline test valgrind"
+REQUIRED_USE="?? ( memcheck valgrind )"
+
+RESTRICT="!test? ( test )"
+
+# The minimum set of packages needed for basic GAP operation. You can
+# actually start gap without these by passing "--bare" to it on the CLI,
+# but don't expect anything to work.
+REQUIRED_PKGS="
+	dev-gap/gapdoc
+	dev-gap/primgrp
+	dev-gap/smallgrp
+	dev-gap/transgrp"
+
+# The packages aren't really required, but GAP tries to load them
+# automatically, and will complain to the user if they fail to load.
+# The list of automatically-loaded packages is a user preference, called
+# AutoloadPackages, and the upstream default can be found in
+# lib/package.gi within the GAP source tree. Passing "-A" to GAP on the
+# CLI (or setting that user preference) will suppress the autoload
+# behavior and allow GAP to start without these, which is why we allow
+# the user to skip them with USE=minimal if he knows what he is doing.
+AUTOLOADED_PKGS="
+	dev-gap/autpgrp
+	dev-gap/alnuth
+	dev-gap/crisp
+	dev-gap/ctbllib
+	dev-gap/factint
+	dev-gap/fga
+	dev-gap/irredsol
+	dev-gap/laguna
+	dev-gap/polenta
+	dev-gap/polycyclic
+	dev-gap/resclasses
+	dev-gap/sophus
+	dev-gap/tomlib"
+
+# The test suite will fail without the "required" subset.
+BDEPEND="test? ( ${REQUIRED_PKGS} )"
+
+DEPEND="dev-libs/gmp:=
+	sys-libs/zlib
+	valgrind? ( dev-debug/valgrind )
+	readline? ( sys-libs/readline:= )"
+
+RDEPEND="${DEPEND}"
+
+# If you _really_ want to install GAP without the set of required
+# packages, use package.provided.
+PDEPEND="${REQUIRED_PKGS} !minimal? ( ${AUTOLOADED_PKGS} )"
+
+PATCHES=( "${FILESDIR}/${P}-objfunc-voidptr.patch" )
+
+pkg_setup() {
+	if use valgrind; then
+		elog "If you enable the use of valgrind during building"
+		elog "be sure that you have enabled the proper flags"
+		elog "in gcc to support it:"
+		elog "https://wiki.gentoo.org/wiki/Debugging#Valgrind"
+	fi
+}
+
+src_prepare() {
+	# Remove these to be extra sure we don't use bundled libraries.
+	rm -r extern || die
+	rm -r hpcgap/extern || die
+
+	# The Makefile just tells you to run ./configure, which then
+	# produces a GNUmakefile.
+	rm Makefile || die
+
+	default
+}
+
+src_configure() {
+	# We unset $ABI because GAP uses it internally for something else.
+	# --without-gmp and --without-zlib both trigger an AC_MSG_ERROR
+	local myeconfargs=(
+		ABI=""
+		--with-gmp
+		--with-zlib
+		$(use_enable cpu_flags_x86_popcnt popcnt)
+		$(use_enable memcheck memory-checking)
+		$(use_enable valgrind)
+		$(use_with readline)
+		$(use_enable debug)
+	)
+	econf "${myeconfargs[@]}"
+}
+
+src_compile() {
+	# Without this, the default is a quiet build.
+	emake V=1
+}
+
+src_test() {
+	# We need to specify additional root paths because otherwise the
+	# recently-built GAP doesn't know where to look for the "required"
+	# packages (which must already be installed). The two paths we
+	# append to $S are where those packages wind up.
+	local gaproots="${S}/;"
+	gaproots+="${EPREFIX}/usr/$(get_libdir)/gap/;"
+	gaproots+="${EPREFIX}/usr/share/gap/"
+
+	# GAPARGS is a Makefile variable that exists for this purpose. We
+	# use "-A" to hide the warnings about missing autoloaded-but-not-
+	# required packages. The tee/pipefail works around a glitch in
+	# dev-gap/browse that can clobber your terminal.
+	eshopts_push -o pipefail
+	emake GAPARGS="-A -l '${gaproots}'" check | tee test-suite.log \
+		|| die "test suite failed, see test-suite.log"
+	eshopts_pop
+}
+
+src_install() {
+	default
+
+	# Manually install Makefile.gappkg
+	insinto usr/share/gap/etc
+	doins etc/Makefile.gappkg
+
+	# la files removal
+	find "${ED}" -type f -name '*.la' -delete || die
+}