在 C 源文件中包含具有命名空间的 C++ 头文件会导致编译错误

Objective of my task: Specific non system thread (cooperative threading actually) safe module is duplicated to create a system thread safe version to support different needs in the system. But instead of creating sys_XXX functions to keep the compatibility, we have decided to create a namespace to protect the system thread version in a C++ header file. I can actually include this in the CPP file and work happily but i just realised my funcInit call is not called before it reaches the CPP file control. Unfortunately this init for the cooperative threading version is in a C file. Now i need to init my system thread safe version from the same place, but im have been blocked by the compilation error which are hard to solve from my knowledge.

编译错误日志:-

In file included from sysinit.c:87:
sys_unicode.h:39: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'SystemThreadUtils' <== corresponds to line [namespace SystemThreadUtils {]
sysinit.c:88:
sysinit.c:512: error: expected identifier or '(' before string constant <== corresponds to line [extern "C" bool SystemThreadUtils::funcInit(void);]
sysinit.c:513: error: expected identifier or '(' before string constant <== corresponds to line [extern "C" bool SystemThreadUtils::funcTerm(void);]
sysinit.c: In function 'SysInit':
sysinit.c:817: error: 'SystemThreadUtils' undeclared (first use in this function) <= corresponds to line [SystemThreadUtils::funcInit();]
sysinit.c:817: error: (Each undeclared identifier is reported only once
sysinit.c:817: error: for each function it appears in.)
sysinit.c:817: error: expected ')' before ':' token
sysinit.c: In function 'SysTerm':
sysinit.c:2737: error: expected expression before ':' token <== corresponds to line [SystemThreadUtils::funcTerm();]
sysinit.c:2737: warning: label 'SystemThreadUtils' defined but not used

来源和标题片段仅供参考:-

// all functions called from the C source file
funcInit();
funcA();
funcB();
funcTerm();

// all functions called from the C source file
funcInit() {
}
funcA() {
}
funcB() {
}
funcTerm() {
}

#include "unicode.h"
namespace SystemThreadUtils {

    // below functions called from the C source file
    extern "C" funcInit();
    extern "C" funcTerm();

    // below functions called from the CPP source file
    funcA();
    funcB();
}

#include "sys_unicode.h"

namespace SystemThreadUtils {

    // below functions are called from C source
    funcInit() {
    }
    funcTerm() {
    }

    // below methods are called from CPP source
    funcA() {
    }
    funcB() {
    }
}

#include "sys_unicode.h"

using namespace SystemThreadUtils;

utils::utils_init()
{
   funcA();
   funcB();
}

#include "sys_unicode.h"

extern "C" bool SystemThreadUtils::funcInit(void);
extern "C" bool SystemThreadUtils::funcTerm(void);

SysInit ()
{
   funcInit(); // non system thread safe version
   SystemThreadUtils::funcInit();  // system thread safe version
}
SysTerm ()
{
   funcTerm(); // non system thread safe version
   SystemThreadUtils::funcTerm();  // system thread safe version
}

//C/C++ - header "sys_unicode_for_c.h"

#ifdef __cplusplus
extern "C" {
#endif

  void STU_funcInit();
  void STU_funcTerm();

#ifdef __cplusplus
} //end extern "C"
#endif

//C++-source: sys_unicode_for_c.hpp
#include "sys_unicode.h"

extern "C" {
  void STU_funcInit() {
    SystemThreadUtils::funcInit();
  }
  void STU_funcTerm() {
    SystemThreadUtils::funcTerm();
  }
}