From d934827bf44b7cfcf6711964418148fa60877668 Mon Sep 17 00:00:00 2001
From: V3n3RiX <venerix@redcorelinux.org>
Date: Wed, 25 Nov 2020 22:39:15 +0000
Subject: gentoo resync : 25.11.2020

---
 eclass/toolchain.eclass | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

(limited to 'eclass/toolchain.eclass')

diff --git a/eclass/toolchain.eclass b/eclass/toolchain.eclass
index 32996a2f8f71..59f8660a3d90 100644
--- a/eclass/toolchain.eclass
+++ b/eclass/toolchain.eclass
@@ -181,6 +181,7 @@ if [[ ${PN} != "kgcc64" && ${PN} != gcc-* ]] ; then
 	tc_version_is_at_least 9.1 && IUSE+=" lto"
 	tc_version_is_at_least 10 && IUSE+=" zstd" TC_FEATURES+=(zstd)
 	tc_version_is_at_least 11 && IUSE+=" valgrind" TC_FEATURES+=(valgrind)
+	tc_version_is_at_least 11 && IUSE+=" custom-cflags"
 fi
 
 if tc_version_is_at_least 10; then
@@ -1391,12 +1392,18 @@ downgrade_arch_flags() {
 }
 
 gcc_do_filter_flags() {
-	# Be conservative here:
-	# - don't allow -O3 and like to over-optimize libgcc # 701786
-	# - don't allow -O0 to generate potentially invalid startup code
-	strip-flags
-	filter-flags '-O?'
-	append-flags -O2
+	# Allow users to explicitly avoid flag sanitization via
+	# USE=custom-cflags.
+	if ! _tc_use_if_iuse custom-cflags; then
+		# Over-zealous CFLAGS can often cause problems.  What may work for one
+		# person may not work for another.  To avoid a large influx of bugs
+		# relating to failed builds, we strip most CFLAGS out to ensure as few
+		# problems as possible.
+		strip-flags
+		# Lock gcc at -O2; we want to be conservative here.
+		filter-flags '-O?'
+		append-flags -O2
+	fi
 
 	# dont want to funk ourselves
 	filter-flags '-mabi*' -m31 -m32 -m64
-- 
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