Android So编译错误

今天和往常一样调用脚本编译so，突然提示如下错误：

../../base/allocator/allocator_extension.h:17:45: error: unknown type name 'size_t'
using AllocHookFunc = void (*)(const void*, size_t);
                                            ^
../../base/allocator/allocator_extension.h:28:55: error: unknown type name 'size_t'
BASE_EXPORT bool GetNumericProperty(const char* name, size_t* value);
                                                      ^
In file included from ../../base/allocator/allocator_extension.cc:7:
In file included from ../../base/logging.h:11:
In file included from ../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:61:
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:74:64: error: use of undeclared identifier 'strchr'
char* __libcpp_strchr(const char* __s, int __c) {return (char*)strchr(__s, __c);}
                                                               ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:81:75: error: use of undeclared identifier 'strpbrk'
char* __libcpp_strpbrk(const char* __s1, const char* __s2) {return (char*)strpbrk(__s1, __s2);}
                                                                          ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:88:65: error: use of undeclared identifier 'strrchr'; did you mean 'strchr'?
char* __libcpp_strrchr(const char* __s, int __c) {return (char*)strrchr(__s, __c);}
                                                                ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:76:13: note: 'strchr' declared here
const char* strchr(const char* __s, int __c) {return __libcpp_strchr(__s, __c);}
            ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:95:49: error: unknown type name 'size_t'
void* __libcpp_memchr(const void* __s, int __c, size_t __n) {return (void*)memchr(__s, __c, __n);}
                                                ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:97:46: error: unknown type name 'size_t'
const void* memchr(const void* __s, int __c, size_t __n) {return __libcpp_memchr(__s, __c, __n);}
                                             ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:99:46: error: unknown type name 'size_t'
      void* memchr(      void* __s, int __c, size_t __n) {return __libcpp_memchr(__s, __c, __n);}
                                             ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:102:74: error: use of undeclared identifier 'strstr'; did you mean 'strchr'?
char* __libcpp_strstr(const char* __s1, const char* __s2) {return (char*)strstr(__s1, __s2);}
                                                                         ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:78:13: note: 'strchr' declared here
      char* strchr(      char* __s, int __c) {return __libcpp_strchr(__s, __c);}
            ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:102:74: error: no matching function for call to 'strchr'
char* __libcpp_strstr(const char* __s1, const char* __s2) {return (char*)strstr(__s1, __s2);}
                                                                         ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:78:13: note: candidate disabled: <no message provided>
      char* strchr(      char* __s, int __c) {return __libcpp_strchr(__s, __c);}
            ^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:102:81: error: cannot initialize a parameter of type 'char *' with an lvalue of type 'const char *'
char* __libcpp_strstr(const char* __s1, const char* __s2) {return (char*)strstr(__s1, __s2);}
                                                                                ^~~~
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:78:32: note: passing argument to parameter '__s' here
      char* strchr(      char* __s, int __c) {return __libcpp_strchr(__s, __c);}
                               ^
In file included from ../../base/allocator/allocator_extension.cc:7:
In file included from ../../base/logging.h:11:
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:69:9: error: no member named 'size_t' in the global namespace
using ::size_t;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:70:9: error: no member named 'memcpy' in the global namespace; did you mean 'memchr'?
using ::memcpy;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:99:13: note: 'memchr' declared here
      void* memchr(      void* __s, int __c, size_t __n) {return __libcpp_memchr(__s, __c, __n);}
            ^
In file included from ../../base/allocator/allocator_extension.cc:7:
In file included from ../../base/logging.h:11:
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:71:9: error: no member named 'memmove' in the global namespace
using ::memmove;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:72:9: error: no member named 'strcpy' in the global namespace; did you mean 'strchr'?
using ::strcpy;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:76:13: note: 'strchr' declared here
const char* strchr(const char* __s, int __c) {return __libcpp_strchr(__s, __c);}
            ^
In file included from ../../base/allocator/allocator_extension.cc:7:
In file included from ../../base/logging.h:11:
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:73:9: error: no member named 'strncpy' in the global namespace
using ::strncpy;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:74:9: error: no member named 'strcat' in the global namespace; did you mean 'strchr'?
using ::strcat;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:76:13: note: 'strchr' declared here
const char* strchr(const char* __s, int __c) {return __libcpp_strchr(__s, __c);}
            ^
In file included from ../../base/allocator/allocator_extension.cc:7:
In file included from ../../base/logging.h:11:
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:75:9: error: no member named 'strncat' in the global namespace
using ::strncat;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/cstring:76:9: error: no member named 'memcmp' in the global namespace; did you mean 'memchr'?
using ::memcmp;
      ~~^
../../../../../../../tool/android-ndk-r16b/sources/cxx-stl/llvm-libc++/include/string.h:99:13: note: 'memchr' declared here
      void* memchr(      void* __s, int __c, size_t __n) {return __libcpp_memchr(__s, __c, __n);}
            ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

看到这些错误一脸懵逼，size_t 不是基础类型吗，怎么会找不到。
google 一番没有任何结果，可以明确知到不是代码逻辑问题，是依赖的环境变量问题，具体的是哪个环境引起的错误，一头雾水。

经过一番测试后找到了问题原因：
xcode 版本升级为11.0 后， gcc 依赖的编译环境发生变化，导致编译错误。
解决方案：
安装一个xcode 10.2版本，重新编译后，问题消失
tip:中间替换了ndk，sdk等版本来确定是否因为这些问题导致

mac 中同时安装不同版本的xcode，可以使用如下命令切换主xcode

$ sudo xcode-select -switch /Applications/Xcode.app（xcode保存的位置）
Password:// 输入密码后就可以修改成功
$ xcodebuild -version 
Xcode 10.2.1
Build version 10E1001
$ xcode-select -p  
/Users/Documents/tool/Xcode.app/Contents/Developer