From a4bf17e87a965ed7f2bb1d2921fb9dd820c79a96 Mon Sep 17 00:00:00 2001
From: Yang Yujie <yangyujie@loongson.cn>
Date: Thu, 7 Sep 2023 14:50:10 +0800
Subject: [PATCH 069/124] LoongArch: Adjust C++ multilib header layout.

For LoongArch, the toplevel library build is always aliased to
one of the multilib variants.  This patch installs it with the
actual MULTISUBDIR (instead of ".") so that the headers can be
reached by the compiler.

This patch is an update of
https://gcc.gnu.org/pipermail/gcc-patches/2023-September/629435.html

libstdc++-v3/ChangeLog:

	* configure.host: Register t-loongarch in tmake_file.
	* config/cpu/loongarch/t-loongarch: New file.  Manually refresh
	MULTISUBDIR with $(shell $(CXX) --print-multi-directory).

Signed-off-by: Peng Fan <fanpeng@loongson.cn>
Signed-off-by: ticat_fp <fanpeng@loongson.cn>
---
 libstdc++-v3/config/cpu/loongarch/t-loongarch | 1 +
 libstdc++-v3/configure.host                   | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 libstdc++-v3/config/cpu/loongarch/t-loongarch

diff --git a/libstdc++-v3/config/cpu/loongarch/t-loongarch b/libstdc++-v3/config/cpu/loongarch/t-loongarch
new file mode 100644
index 000000000..adfc8ebb9
--- /dev/null
+++ b/libstdc++-v3/config/cpu/loongarch/t-loongarch
@@ -0,0 +1 @@
+AM_MAKEFLAGS += " MULTISUBDIR=/$(shell $(CXX) --print-multi-directory)"
diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
index ec32980aa..592160e6d 100644
--- a/libstdc++-v3/configure.host
+++ b/libstdc++-v3/configure.host
@@ -315,7 +315,10 @@ esac
 # Set any OS-dependent and CPU-dependent bits.
 # THIS TABLE IS SORTED.  KEEP IT THAT WAY.
 case "${host}" in
-  *-*-linux* | *-*-uclinux*)
+ loongarch*)
+    tmake_file="cpu/loongarch/t-loongarch"
+    ;;
+ *-*-linux* | *-*-uclinux*)
     case "${host_cpu}" in
       i[567]86)
         abi_baseline_pair=i486-linux-gnu
-- 
2.33.0