dev-debug/systemtap: conditionally install /usr/bin/dtrace

systemtap provides a 'dtrace' script at /usr/bin/dtrace which obviously
clashes with dev-debug/dtrace. The reasons for this are complicated,
but this 'dtrace' is only used by some packages for userspace probes.

The plan, for now, is:
* to modify packages to look for stap-dtrace instead;
* users can set USE=dtrace-symlink to get systemtap to install /usr/bin/dtrace
  again to build applications locally or as a workaround for unported applications/scripts;
* contact systemtap upstream about renaming it and providing a symlink
  conditionally as we are, and providing a pkgconfig var for getting the
  name

Bug: https://bugs.gentoo.org/938302
Signed-off-by: Sam James <sam@gentoo.org>

dev-debug/systemtap/metadata.xml

@@ -6,6 +6,10 @@
 </maintainer>
   <use>
     <flag name="debuginfod">Enable debuginfod support via <pkg>dev-libs/elfutils</pkg> libdebuginfod</flag>
+    <flag name="dtrace-symlink">
+        Provide /usr/bin/dtrace symlink pointing to /usr/bin/stap-dtrace.
+        This prevents coinstallation with <pkg>dev-debug/dtrace</pkg>.
+    </flag>
     <flag name="libvirt">Support probing of libvirt domains.</flag>
   </use>
 </pkgmetadata>

dev-debug/systemtap/systemtap-5.1-r1.ebuild

@@ -0,0 +1,160 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{10..12} pypy3 )
+
+inherit autotools flag-o-matic linux-info python-single-r1 toolchain-funcs
+
+DESCRIPTION="Linux trace/probe tool"
+HOMEPAGE="https://sourceware.org/systemtap/"
+if [[ ${PV} == 9999 ]] ; then
+	EGIT_REPO_URI="https://sourceware.org/git/systemtap.git"
+	inherit git-r3
+else
+	SRC_URI="https://sourceware.org/ftp/${PN}/releases/${P}.tar.gz"
+	KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~ia64 ~loong ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86"
+fi
+
+LICENSE="GPL-2"
+SLOT="0"
+IUSE="debuginfod dtrace-symlink libvirt selinux sqlite +ssl test zeroconf"
+
+CDEPEND="
+	${PYTHON_DEPS}
+
+	dev-libs/boost:=
+	>=dev-libs/elfutils-0.142[debuginfod?]
+	dev-libs/json-c:=
+	sys-libs/ncurses:=
+	sys-libs/readline:=
+
+	libvirt? ( >=app-emulation/libvirt-1.0.2 )
+	selinux? ( sys-libs/libselinux )
+	sqlite? ( dev-db/sqlite:3 )
+	ssl? (
+		dev-libs/nspr
+		dev-libs/nss
+	)
+	zeroconf? ( net-dns/avahi )
+"
+DEPEND="
+	${CDEPEND}
+	app-alternatives/cpio
+	app-text/xmlto
+	$(python_gen_cond_dep 'dev-python/setuptools[${PYTHON_USEDEP}]')
+	>=sys-devel/gettext-0.18.2
+
+	libvirt? ( dev-libs/libxml2 )
+"
+RDEPEND="
+	${CDEPEND}
+	acct-group/stapdev
+	acct-group/stapsys
+	acct-group/stapusr
+"
+# which: https://sourceware.org/PR32106
+BDEPEND="
+	test? (
+		dev-util/dejagnu
+		|| (
+			net-analyzer/netcat
+			net-analyzer/openbsd-netcat
+		)
+		sys-apps/which
+	)
+"
+
+CONFIG_CHECK="~KPROBES ~RELAY ~DEBUG_FS"
+ERROR_KPROBES="${PN} requires support for KProbes Instrumentation (KPROBES) - this can be enabled in 'Instrumentation Support -> Kprobes'."
+ERROR_RELAY="${PN} works with support for user space relay support (RELAY) - this can be enabled in 'General setup -> Kernel->user space relay support (formerly relayfs)'."
+ERROR_DEBUG_FS="${PN} works best with support for Debug Filesystem (DEBUG_FS) - this can be enabled in 'Kernel hacking -> Debug Filesystem'."
+
+DOCS="AUTHORS HACKING NEWS README"
+REQUIRED_USE="${PYTHON_REQUIRED_USE}"
+RESTRICT="!test? ( test )"
+PATCHES=(
+	"${FILESDIR}/${PN}-3.1-ia64.patch"
+)
+
+pkg_setup() {
+	linux-info_pkg_setup
+	python-single-r1_pkg_setup
+}
+
+src_prepare() {
+	python_fix_shebang .
+
+	sed -i \
+		-e 's#$(INSTALL_DATA) $(srcdir)/stap-exporter.options "$(DESTDIR)$(sysconfdir)/sysconfig/stap-exporter"##g' \
+		stap-exporter/Makefile.am || die "Failed to modify stap-exporter Makefile.am"
+	sed -i \
+		-e '\#^EnvironmentFile=-/etc/sysconfig/stap-exporter#d' \
+		-e 's#$PORT $KEEPALIVE $SCRIPTS $OPTIONS#--port 9900 --keepalive 300#g' \
+		stap-exporter/stap-exporter.service || die "Failed to adapt stap-exporter.service"
+
+	default
+	eautoreconf
+}
+
+src_configure() {
+	local myeconfargs=(
+		--cache-file="${S}"/config.cache
+		--disable-docs
+		--disable-grapher
+		--disable-refdocs
+		--disable-server
+		--disable-Werror
+		# Our toolchain sets this for us already and adding in
+		# -D_FORTIFY_SOURCE=2 breaks builds w/ no optimisation.
+		# This option (at least as of 4.5) doesn't pass -fno* etc,
+		# it just doesn't _add_ options, which is good. If it changes
+		# to actually pass -fno-stack-protector and friends, we'll
+		# need to change course. Forcing =2 also has problems for
+		# setting it to 3.
+		# bug #794667.
+		--disable-ssp
+		--enable-pie
+		--with-python3
+		--without-java
+		--without-openssl
+		--without-python2-probes
+		--without-rpm
+		$(use_enable libvirt virt)
+		$(use_enable sqlite)
+		$(use_with debuginfod)
+		$(use_with zeroconf avahi)
+		$(use_with ssl nss)
+		$(use_with selinux)
+	)
+
+	# Use bash because of bashisms with brace expansion in Makefile.am (bug #913947)
+	CONFIG_SHELL="${BROOT}"/bin/bash PYTHON3="${PYTHON}" econf "${myeconfargs[@]}"
+}
+
+src_test() {
+	# TODO: Install tests like dev-debug/dtrace[install-tests] and
+	# e.g. Fedora does.
+	(
+		strip-flags
+		filter-flags '-fcf-protection=*'
+		filter-flags '-fdiagnostics-color=*' '-fdiagnostics-urls=*'
+		filter-flags '-g*'
+		filter-lto
+		tc-ld-force-bfd
+		emake -Onone -k check CFLAGS="${CFLAGS}" CXXFLAGS="${CXXFLAGS}" LDFLAGS="${LDFLAGS}"
+	)
+}
+
+src_install() {
+	default
+	python_optimize
+
+	# Avoid file collision with dev-debug/dtrace
+	mv "${ED}"/usr/bin/dtrace "${ED}"/usr/bin/stap-dtrace || die
+
+	if use dtrace-symlink ; then
+		dosym stap-dtrace /usr/bin/dtrace
+	fi
+}

dev-debug/systemtap/systemtap-9999.ebuild

@@ -19,7 +19,7 @@ fi
 
 LICENSE="GPL-2"
 SLOT="0"
-IUSE="debuginfod libvirt selinux sqlite +ssl test zeroconf"
+IUSE="debuginfod dtrace-symlink libvirt selinux sqlite +ssl test zeroconf"
 
 CDEPEND="
 	${PYTHON_DEPS}
@@ -151,4 +151,11 @@ src_test() {
 src_install() {
 	default
 	python_optimize
+
+	# Avoid file collision with dev-debug/dtrace
+	mv "${ED}"/usr/bin/dtrace "${ED}"/usr/bin/stap-dtrace || die
+
+	if use dtrace-symlink ; then
+		dosym stap-dtrace /usr/bin/dtrace
+	fi
 }