epunt-cxx.eclass: Split C++ check punting code out of eutils

Split the epunt_cxx (plus internal code) to a dedicated eclass. This is
rarely needed, usually indicates a dead upstream and requires
the ELT-patches framework. The patches are going to be split to
a separate package, and the new eclass will therefore need to DEPEND
on it. We do not want the dependency to apply to all eutils users
though.

eclass/epunt-cxx.eclass

@@ -0,0 +1,65 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: epunt-cxx.eclass
+# @MAINTAINER:
+# [email protected]
+# @BLURB: A function to punt C++ compiler checks from autoconf
+# @DESCRIPTION:
+# Support for punting C++ compiler checks from autoconf (based
+# on ELT-patches).
+
+if [[ -z ${_EPUNT_CXX_ECLASS} ]]; then
+
+# TODO: replace this with 'inherit eutils' once eutils stops inheriting
+# us
+if ! declare -F eqawarn >/dev/null ; then
+ eqawarn() {
+ has qa ${PORTAGE_ELOG_CLASSES} && ewarn "$@"
+ :
+ }
+fi
+
+# If an overlay has eclass overrides, but doesn't actually override the
+# libtool.eclass, we'll have ECLASSDIR pointing to the active overlay's
+# eclass/ dir, but libtool.eclass is still in the main Gentoo tree. So
+# add a check to locate the ELT-patches/ regardless of what's going on.
+# Note: Duplicated in libtool.eclass.
+_EUTILS_ECLASSDIR_LOCAL=${BASH_SOURCE[0]%/*}
+eutils_elt_patch_dir() {
+ local d="${ECLASSDIR}/ELT-patches"
+ if [[ ! -d ${d} ]] ; then
+ d="${_EUTILS_ECLASSDIR_LOCAL}/ELT-patches"
+ fi
+ echo "${d}"
+}
+
+# @FUNCTION: epunt_cxx
+# @USAGE: [dir to scan]
+# @DESCRIPTION:
+# Many configure scripts wrongly bail when a C++ compiler could not be
+# detected. If dir is not specified, then it defaults to ${S}.
+#
+# https://bugs.gentoo.org/73450
+epunt_cxx() {
+ local dir=$1
+ [[ -z ${dir} ]] && dir=${S}
+ ebegin "Removing useless C++ checks"
+ local f p any_found
+ while IFS= read -r -d '' f; do
+ for p in "$(eutils_elt_patch_dir)"/nocxx/*.patch ; do
+ if patch --no-backup-if-mismatch -p1 "${f}" "${p}" >/dev/null ; then
+ any_found=1
+ break
+ fi
+ done
+ done < <(find "${dir}" -name configure -print0)
+
+ if [[ -z ${any_found} ]]; then
+ eqawarn "epunt_cxx called unnecessarily (no C++ checks to punt)."
+ fi
+ eend 0
+}
+
+_EPUNT_CXX_ECLASS=1
+fi #_EPUNT_CXX_ECLASS

eclass/eutils.eclass

@@ -20,7 +20,8 @@ _EUTILS_ECLASS=1
 # implicitly inherited (now split) eclasses
 case ${EAPI:-0} in
 0|1|2|3|4|5|6)
- inherit epatch estack ltprune multilib toolchain-funcs
+ # note: we want to remove epunt-cxx retroactively for #566424
+ inherit epatch epunt-cxx estack ltprune multilib toolchain-funcs
  ;;
 esac
 
@@ -740,47 +741,6 @@ built_with_use() {
  [[ ${opt} = "-a" ]]
 }
 
-# If an overlay has eclass overrides, but doesn't actually override the
-# libtool.eclass, we'll have ECLASSDIR pointing to the active overlay's
-# eclass/ dir, but libtool.eclass is still in the main Gentoo tree. So
-# add a check to locate the ELT-patches/ regardless of what's going on.
-# Note: Duplicated in libtool.eclass.
-_EUTILS_ECLASSDIR_LOCAL=${BASH_SOURCE[0]%/*}
-eutils_elt_patch_dir() {
- local d="${ECLASSDIR}/ELT-patches"
- if [[ ! -d ${d} ]] ; then
- d="${_EUTILS_ECLASSDIR_LOCAL}/ELT-patches"
- fi
- echo "${d}"
-}
-
-# @FUNCTION: epunt_cxx
-# @USAGE: [dir to scan]
-# @DESCRIPTION:
-# Many configure scripts wrongly bail when a C++ compiler could not be
-# detected. If dir is not specified, then it defaults to ${S}.
-#
-# https://bugs.gentoo.org/73450
-epunt_cxx() {
- local dir=$1
- [[ -z ${dir} ]] && dir=${S}
- ebegin "Removing useless C++ checks"
- local f p any_found
- while IFS= read -r -d '' f; do
- for p in "$(eutils_elt_patch_dir)"/nocxx/*.patch ; do
- if patch --no-backup-if-mismatch -p1 "${f}" "${p}" >/dev/null ; then
- any_found=1
- break
- fi
- done
- done < <(find "${dir}" -name configure -print0)
-
- if [[ -z ${any_found} ]]; then
- eqawarn "epunt_cxx called unnecessarily (no C++ checks to punt)."
- fi
- eend 0
-}
-
 # @FUNCTION: make_wrapper
 # @USAGE: <wrapper> <target> [chdir] [libpaths] [installpath]
 # @DESCRIPTION: