eclass/meson: Sync with Gentoo

It's from Gentoo commit 5a465ec448ea48b9dd9471e4d15b7669a77e4536.

sdk_container/src/third_party/portage-stable/eclass/meson.eclass

@@ -1,11 +1,11 @@
-# Copyright 2017-2021 Gentoo Authors
+# Copyright 2017-2022 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 # @ECLASS: meson.eclass
 # @MAINTAINER:
 # William Hubbs <williamh@gentoo.org>
 # Mike Gilbert <floppym@gentoo.org>
-# @SUPPORTED_EAPIS: 6 7 8
+# @SUPPORTED_EAPIS: 7 8
 # @BLURB: common ebuild functions for meson-based packages
 # @DESCRIPTION:
 # This eclass contains the default phase functions for packages which
@@ -35,36 +35,34 @@
 # @CODE
 
 case ${EAPI} in
-	6|7|8) ;;
+	7|8) ;;
 	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
 esac
 
 if [[ -z ${_MESON_ECLASS} ]]; then
 _MESON_ECLASS=1
 
-[[ ${EAPI} == 6 ]] && inherit eapi7-ver
 inherit multiprocessing ninja-utils python-utils-r1 toolchain-funcs
 
 EXPORT_FUNCTIONS src_configure src_compile src_test src_install
 
-_MESON_DEPEND=">=dev-util/meson-0.57.0
-	>=dev-util/ninja-1.8.2
+BDEPEND=">=dev-util/meson-0.62.2
+	${NINJA_DEPEND}
 	dev-util/meson-format-array
 "
 
-if [[ ${EAPI} == 6 ]]; then
-	DEPEND=${_MESON_DEPEND}
-else
-	BDEPEND=${_MESON_DEPEND}
-fi
-
-# @ECLASS-VARIABLE: BUILD_DIR
+# @ECLASS_VARIABLE: BUILD_DIR
 # @DEFAULT_UNSET
 # @DESCRIPTION:
 # Build directory, location where all generated files should be placed.
 # If this isn't set, it defaults to ${WORKDIR}/${P}-build.
 
-# @ECLASS-VARIABLE: EMESON_SOURCE
+# @ECLASS_VARIABLE: EMESON_BUILDTYPE
+# @DESCRIPTION:
+# The buildtype value to pass to meson setup.
+: ${EMESON_BUILDTYPE=plain}
+
+# @ECLASS_VARIABLE: EMESON_SOURCE
 # @DEFAULT_UNSET
 # @DESCRIPTION:
 # The location of the source files for the project; this is the source
@@ -280,6 +278,8 @@ meson_feature() {
 meson_src_configure() {
 	debug-print-function ${FUNCNAME} "$@"
 
+	[[ -n "${NINJA_DEPEND}" ]] || ewarn "Unknown value '${NINJA}' for \${NINJA}"
+
 	local BUILD_CFLAGS=${BUILD_CFLAGS}
 	local BUILD_CPPFLAGS=${BUILD_CPPFLAGS}
 	local BUILD_CXXFLAGS=${BUILD_CXXFLAGS}
@@ -310,7 +310,6 @@ meson_src_configure() {
 
 	local mesonargs=(
 		meson setup
-		--buildtype plain
 		--libdir "$(get_libdir)"
 		--localstatedir "${EPREFIX}/var/lib"
 		--prefix "${EPREFIX}/usr"
@@ -319,8 +318,22 @@ meson_src_configure() {
 		--build.pkg-config-path "${BUILD_PKG_CONFIG_PATH}${BUILD_PKG_CONFIG_PATH:+:}${EPREFIX}/usr/share/pkgconfig"
 		--pkg-config-path "${PKG_CONFIG_PATH}${PKG_CONFIG_PATH:+:}${EPREFIX}/usr/share/pkgconfig"
 		--native-file "$(_meson_create_native_file)"
+
+		# gcc[pch] is masked in profiles due to consistent bugginess
+		# without forcing this off, some packages may fail too (like gjs,
+		# bug #839549), but in any case, we don't want to bother attempting
+		# this.
+		-Db_pch=false
+
+		# It's Gentoo policy to not have builds die on blanket -Werror, as it's
+		# an upstream development matter. bug #754279.
+		-Dwerror=false
 	)
 
+	if [[ -n ${EMESON_BUILDTYPE} ]]; then
+		mesonargs+=( --buildtype "${EMESON_BUILDTYPE}" )
+	fi
+
 	if tc-is-cross-compiler; then
 		mesonargs+=( --cross-file "$(_meson_create_cross_file)" )
 	fi
@@ -394,6 +407,7 @@ meson_src_test() {
 	debug-print-function ${FUNCNAME} "$@"
 
 	local mesontestargs=(
+		--print-errorlogs
 		-C "${BUILD_DIR}"
 		--num-processes "$(makeopts_jobs "${MAKEOPTS}")"
 		"$@"
@@ -414,6 +428,7 @@ meson_install() {
 	local mesoninstallargs=(
 		-C "${BUILD_DIR}"
 		--destdir "${D}"
+		--no-rebuild
 		"$@"
 	)