From cf3c4e4c108dc54d526b3361db156008c2b0ca62 Mon Sep 17 00:00:00 2001
From: Flatcar Buildbot <buildbot@flatcar-linux.org>
Date: Mon, 1 Jan 2024 07:13:50 +0000
Subject: [PATCH] eclass/toolchain-funcs: Sync with Gentoo

It's from Gentoo commit 2aea6c3ff2181ad96187e456a3307609fd288d4c.
---
 .../eclass/toolchain-funcs.eclass             | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/sdk_container/src/third_party/portage-stable/eclass/toolchain-funcs.eclass b/sdk_container/src/third_party/portage-stable/eclass/toolchain-funcs.eclass
index 5da9306386..cde84e6f34 100644
--- a/sdk_container/src/third_party/portage-stable/eclass/toolchain-funcs.eclass
+++ b/sdk_container/src/third_party/portage-stable/eclass/toolchain-funcs.eclass
@@ -1230,4 +1230,25 @@ tc-get-build-ptr-size() {
 		die "Could not determine CBUILD pointer size"
 }
 
+# @FUNCTION: tc-is-lto
+# @RETURN: Shell true if we are using LTO, shell false otherwise
+tc-is-lto() {
+	local f="${T}/test-lto.o"
+
+	case $(tc-get-compiler-type) in
+		clang)
+			$(tc-getCC) ${CFLAGS} -c -o "${f}" -x c - <<<"" || die
+			# If LTO is used, clang will output bytecode and llvm-bcanalyzer
+			# will run successfully.  Otherwise, it will output plain object
+			# file and llvm-bcanalyzer will exit with error.
+			llvm-bcanalyzer "${f}" &>/dev/null && return 0
+			;;
+		gcc)
+			$(tc-getCC) ${CFLAGS} -c -o "${f}" -x c - <<<"" || die
+			[[ $($(tc-getREADELF) -S "${f}") == *.gnu.lto* ]] && return 0
+			;;
+	esac
+	return 1
+}
+
 fi