ubuntu 20.04安装GCC G++ 6.2，支持c++ 14

1. 下载源码包

wget http://ftp.gnu.org/gnu/gcc/gcc-6.2.0/gcc-6.2.0.tar.bz2

2. 解压

tar jxf gcc-6.2.0.tar.bz2

3. 下载编译依赖

cd gcc-6.2.0

./contrib/download_prerequisites

4. 生成makefile文件

mkdir gcc-build-6.2.0

cd gcc-build-6.2.0/

../configure -enable-checking=release -enable-languages=c,c++ -disable-multilib

5. 编译

make -j4

 4表示使用4个核心，根据你的CPU来指定。也可不指定任何参数

6. 安装

make install

7. 验证

gcc -v

 

编译过程中遇到的问题：

---

问题1：error: dereferencing pointer to incomplete type ‘struct ucontext’

在函数‘x86_64_fallback_frame_state’中: ./md-unwind-support.h:65:47: 错误： dereferencing pointer to incomplete type ‘struct ucontext’       
 sc = (struct sigcontext *) (void *) &uc_->uc_mcontext;    

解决方案：

 struct ucontext * uc_ = context->cfa;
修改为

struct ucontext_t * uc_ = context->cfa;
重新编译make

---

问题2：sanitizer_platform_limits_posix.cc:158:23: 致命错误：sys/ustat.h：没有那个文件或目录

../../.././libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc:159:
28: fatal error: sys/ustat.h: No such file or directory
 #include <sys/ustat.h>
                       ^
compilation terminated.

解决方案：

修改libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc文件：

vim libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
首先注释掉 #include <sys/ustat.h> ：
接着在 251 行修改 unsigned struct_ustat_sz = sizeof(struct ustat); 语句
注释掉251行，换行后粘贴以下内容：

  // Use pre-computed size of struct ustat to avoid <sys/ustat.h> which
  // has been removed from glibc 2.28.
#if defined(__aarch64__) || defined(__s390x__) || defined (__mips64) \
  || defined(__powerpc64__) || defined(__arch64__) || defined(__sparcv9) \
  || defined(__x86_64__)
#define SIZEOF_STRUCT_USTAT 32
#elif defined(__arm__) || defined(__i386__) || defined(__mips__) \
  || defined(__powerpc__) || defined(__s390__)
#define SIZEOF_STRUCT_USTAT 20
#else
#error Unknown size of struct ustat
#endif
  unsigned struct_ustat_sz = SIZEOF_STRUCT_USTAT;
重新make

---

问题3：
../../.././libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc:270:22: 错误： 聚
合‘sigaltstack handler_stack’类型不完全，无法被定义
   struct sigaltstack handler_stack;
                      ^~~~~~~~~~~~~
解决方案：

1.打开libsanitizer/sanitizer_common/sanitizer_linux.h文件，注释第22行的struct sigaltstack;
2.修改31.32行：
uptr internal_sigaltstack(const struct sigaltstack* ss,
                          struct sigaltstack* oss);

修改为
uptr internal_sigaltstack(const void* ss, void* oss);

3.修改libsanitizer/sanitizer_common/sanitizer_linux.cc文件549、550行
uptr internal_sigaltstack(const struct sigaltstack *ss,                                      
                                struct sigaltstack *oss) {

修改为
uptr internal_sigaltstack(const void *ss, void *oss) {

4.修改libsanitizer/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc270行
struct sigaltstack handler_stack;
修改为
stack_t handler_stack;

5.修改libsanitizer/tsan/tsan_platform_linux.cc294行
__res_state *statp = (__res_state*)state;
修改为
struct __res_state *statp = (struct __res_state*)state;
重新make

---

问题4：sanitizer_common/sanitizer_internal_defs.h:254:72: error: size of array ‘assertion_failed__1142’ is negative
解决方案：
修改 /gcc-6.3.0/configure文件
删除文件中 target-libsanitizer \，大概在两千多行
重新make