[ch32v307] support c++

bsp/wch/risc-v/ch32v307v-r1/SConstruct

@@ -24,6 +24,7 @@ env = Environment(tools = ['mingw'],
     AS = rtconfig.AS, ASFLAGS = rtconfig.AFLAGS,
     CC = rtconfig.CC, CFLAGS = rtconfig.CFLAGS,
     AR = rtconfig.AR, ARFLAGS = '-rc',
+    CXX = rtconfig.CXX, CXXFLAGS = rtconfig.CXXFLAGS,
     LINK = rtconfig.LINK, LINKFLAGS = rtconfig.LFLAGS)
 env.PrependENVPath('PATH', rtconfig.EXEC_PATH)
 

bsp/wch/risc-v/ch32v307v-r1/board/linker_scripts/link.lds

@@ -66,6 +66,23 @@ SECTIONS
         __rtmsymtab_end = .;
             . = ALIGN(4);
 
+        /* section information for initial. */
+        . = ALIGN(4);
+        __rt_init_start = .;
+        KEEP(*(SORT(.rti_fn*)))
+        __rt_init_end = .;
+
+        . = ALIGN(4);
+
+        PROVIDE(__ctors_start__ = .);
+        KEEP (*(SORT(.init_array.*)))
+        KEEP (*(.init_array))
+        PROVIDE(__ctors_end__ = .);
+
+        . = ALIGN(4);
+
+        _etext = .;
+
     } >FLASH AT>FLASH
 
     .fini :

bsp/wch/risc-v/ch32v307v-r1/rtconfig.py

@@ -57,6 +57,8 @@ if PLATFORM == 'gcc':
     else:
         CFLAGS += ' -O2'
 
+    CXXFLAGS = CFLAGS
+
     POST_ACTION = OBJCPY + ' -O binary $TARGET ' + TARGET_NAME + '\n'
     POST_ACTION += SIZE + ' $TARGET\n'