$OpenBSD: patch-build_main_mk,v 1.4 2021/08/06 08:02:10 mestre Exp $
Index: build/main.mk
--- build/main.mk.orig
+++ build/main.mk
@@ -334,7 +334,7 @@ LINK_FLAGS+=$(TARGET_FLAGS)
 CXX?=g++
 WINDRES?=windres
 DEPEND_FLAGS:=
-ifneq ($(filter %clang++,$(CXX))$(filter clang++%,$(CXX)),)
+ifneq ($(filter %clang++,$(CXX))$(filter clang++%,$(CXX))$(filter c++,$(CXX)),)
   # Enable C++17 (for the most part supported since clang-5)
   COMPILE_FLAGS+=-std=c++17 -fconstexpr-steps=2000000
   COMPILE_FLAGS+=-Wall -Wextra -Wundef -Wno-invalid-offsetof -Wunused-macros -Wdouble-promotion -Wmissing-declarations -Wshadow -Wold-style-cast -Wzero-as-null-pointer-constant
@@ -361,6 +361,8 @@ else
   else
     $(warning Unsupported compiler: $(CXX), please update Makefile)
   endif
+  # Enable C++11
+  COMPILE_FLAGS+=-std=c++11
 endif
 endif
 
