libxx: Add CXX_STANDARD to select -std=c++??

and default to "c++17"

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

arch/arm/src/common/Toolchain.defs

@@ -234,6 +234,10 @@ endif
 ARCHCFLAGS += -Wstrict-prototypes
 ARCHCXXFLAGS += -nostdinc++
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/arm64/src/Toolchain.defs

@@ -80,6 +80,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef -Werror
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/avr/src/avr/Toolchain.defs

@@ -104,6 +104,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/avr/src/avr32/Toolchain.defs

@@ -51,6 +51,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/mips/src/mips32/Toolchain.defs

@@ -265,6 +265,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/misoc/src/lm32/Toolchain.defs

@@ -77,6 +77,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/or1k/src/mor1kx/Toolchain.defs

@@ -60,6 +60,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/risc-v/src/common/Toolchain.defs

@@ -73,6 +73,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/sparc/src/sparc_v8/Toolchain.defs

@@ -82,6 +82,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/xtensa/src/lx6/Toolchain.defs

@@ -85,6 +85,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

arch/xtensa/src/lx7/Toolchain.defs

@@ -85,6 +85,10 @@ ARCHCXXFLAGS += -fno-common -nostdinc++
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifneq ($(CONFIG_CXX_EXCEPTION),y)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

boards/sim/sim/sim/scripts/Make.defs

@@ -106,6 +106,10 @@ ARCHCXXFLAGS += -ffunction-sections -fdata-sections
 ARCHCFLAGS += -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHCXXFLAGS += -Wall -Wshadow -Wundef
 
+ifneq ($(CONFIG_CXX_STANDARD),)
+  ARCHCXXFLAGS += -std=$(CONFIG_CXX_STANDARD)
+endif
+
 ifeq ($(CONFIG_CXX_EXCEPTION),)
   ARCHCXXFLAGS += -fno-exceptions -fcheck-new
 endif

libs/libxx/Kconfig

@@ -85,6 +85,12 @@ endchoice
 
 endif
 
+config CXX_STANDARD
+	string "Language standard"
+	default "c++17"
+	---help---
+		Possible values: c++98, c++11, c++14, c++17 and c++20
+
 config CXX_EXCEPTION
 	bool "Enable Exception Support"
 

libs/libxx/libcxx.defs

@@ -50,7 +50,6 @@ ifeq ($(wildcard libcxx/.git),)
 	$(call DELDIR, libcxx)
 endif
 
-CXXFLAGS += -std=c++17
 CXXFLAGS += ${DEFINE_PREFIX}_LIBCPP_BUILDING_LIBRARY
 
 ifeq ($(CONFIG_LIBSUPCXX), y)