[openwrt/openwrt] build: let HOST_CXXFLAGS default to HOST_CFLAGS

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/b07099a6fdf05937446c486c8ef78e4cca081724

commit b07099a6fdf05937446c486c8ef78e4cca081724
Author: Michael Pratt <mcpratt at pm.me>
AuthorDate: Thu Jun 20 01:10:21 2024 -0400

    build: let HOST_CXXFLAGS default to HOST_CFLAGS
    
    Usage of g++ should mimic the usage of gcc,
    otherwise, part of a binary or library may have
    optimizations and part of it may not,
    unbeknownst to the users or developers working on a build.
    This can lead to some features like, for example, FORTIFY_SOURCE,
    to have less of an effect or even cause a build error on some hosts.
    
    Therefore, let HOST_CXXFLAGS default to HOST_CFLAGS.
    
    Fixes: 87d489f67 ("build: add HOST_CXXFLAGS for host build")
    Signed-off-by: Michael Pratt <mcpratt at pm.me>
    Link: https://github.com/openwrt/openwrt/pull/15853
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 rules.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rules.mk b/rules.mk
index 91ed9b2085..ae20742bd7 100644
--- a/rules.mk
+++ b/rules.mk
@@ -245,8 +245,8 @@ export PKG_CONFIG
 HOSTCC:=$(STAGING_DIR_HOST)/bin/gcc
 HOSTCXX:=$(STAGING_DIR_HOST)/bin/g++
 HOST_CPPFLAGS:=-I$(STAGING_DIR_HOST)/include $(if $(IS_PACKAGE_BUILD),-I$(STAGING_DIR_HOSTPKG)/include -I$(STAGING_DIR)/host/include)
-HOST_CXXFLAGS:=
 HOST_CFLAGS:=-O2 $(HOST_CPPFLAGS)
+HOST_CXXFLAGS:=$(HOST_CFLAGS)
 HOST_LDFLAGS:=-L$(STAGING_DIR_HOST)/lib $(if $(IS_PACKAGE_BUILD),-L$(STAGING_DIR_HOSTPKG)/lib -L$(STAGING_DIR)/host/lib)
 
 BUILD_KEY=$(TOPDIR)/key-build