--- /usr/portage/dev-util/wasmer/wasmer-0.11.0.ebuild	2020-01-09 21:08:25.408333768 +0900
+++ /usr/local/portage/dev-util/wasmer/wasmer-0.11.0-r1.ebuild	2020-08-13 00:00:40.658211624 +0900
@@ -178,19 +178,31 @@
 LICENSE="MIT Apache-2.0 BSD-2 ISC"
 SLOT="0"
 KEYWORDS="~amd64"
-IUSE=""
+IUSE="llvm cranelift singlepass"
+REQUIRED_USE="
+	|| ( llvm cranelift singlepass )
+"
 
 BDEPEND="
 	dev-util/cmake
 	>=virtual/rust-1.37.0
 "
+# singlepass actually requires nightly rust... :/
+# llvm seems to have some dependencies on llvm use flags or a version or something.
+#
+# Maybe just enable cranelift and cranelift only?
 
 src_prepare() {
 	[[ "${PV}" == *9999* ]] || ln -s ../${P}-git-deps "${ECARGO_HOME}"/git
 	default
 }
 
+src_compile() {
+	cargo_src_compile --features "$(usex cranelift backend-cranelift "") $(usex llvm backend-llvm "") $(usex singlepass backend-singlepass "")" --bin wasmer
+	# kwasmd / loader-kernel seems to depend on backend-singlepass, disabled
+}
+
 src_install() {
-	cargo_src_install
+	cargo_src_install --features "$(usex cranelift backend-cranelift "") $(usex llvm backend-llvm "") $(usex singlepass backend-singlepass "")" --bin wasmer
 	einstalldocs
 }