[cfe-dev] Build libc++ against musl-libc.

[Howard Hinnant]

Thank you for your efforts to port libc++ to musl-libc.

Unfortunately your patch below breaks other platforms.  You will need to isolate your changes such that they only impact your platform.

Howard

On Sep 17, 2013, at 2:25 AM, 邓尧 <torshie at gmail.com> wrote:

> Hi,
> I'm trying to build libc++ against musl-libc ( www.musl-libc.org ), another linux C library. I have successfully built a musl-libc based C toolchain, a freestanding C++ compiler, and some C++ runtime libraries like libcxxrt, libunwind, I even succeeded in building libc++ against musl-libc, but a simple hello-world program won't run.
> 
> the following code would throw a bad_cast exception:
> 
> #include <locale>
> #include <iostream>
> #include <cstdio>
> 
> using namespace std;
> 
> int main() {
>     locale loc("C");
>     //cout.imbue(loc);  // If this line is added, the whole program runs well.
>     cout << "hello" << endl;
>     return 0;
> }
> 
> This is the call stack of the thrown exception:
> #6  0x00000000004ce2d9 in __cxa_throw ()
> #7  0x0000000000422a40 in std::__1::locale::__imp::use_facet(long) const ()
>     at /home/hoolala/workspace/bootcxx/out/libcxx/src/locale.cpp:439
> #8  0x0000000000423379 in std::__1::locale::use_facet(std::__1::locale::id&) const ()
>     at /home/hoolala/workspace/bootcxx/out/libcxx/src/locale.cpp:581
> #9  0x00000000004005ad in std::__1::basic_ostream<char, std::__1::char_traits<char> >& std::__1::operator<< <std::__1::char_traits<char> >(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, char const*) ()
>     at /home/hoolala/workspace/bootcxx/out/sysroot/usr/include/c++/v1/__locale:174
> #10 0x000000000040035a in main () at loc.cpp:12
> 
> I applied a simple patch to the original libc++ code:
> 
> Index: include/__locale
> ===================================================================
> --- include/__locale    (revision 190843)
> +++ include/__locale    (working copy)
> @@ -376,7 +376,7 @@
>      static const mask xdigit = _ISXDIGIT;
>      static const mask blank  = _ISBLANK;
>  #else  // __GLIBC__ || _WIN32 || __APPLE__ || __FreeBSD__ || EMSCRIPTEN || __sun__
> -    typedef unsigned long mask;
> +    typedef unsigned short mask;
>      static const mask space  = 1<<0;
>      static const mask print  = 1<<1;
>      static const mask cntrl  = 1<<2;
> Index: include/locale
> ===================================================================
> --- include/locale    (revision 190843)
> +++ include/locale    (working copy)
> @@ -829,7 +829,7 @@
>          typename remove_reference<decltype(errno)>::type __save_errno = errno;
>          errno = 0;
>          char *__p2;
> -        long long __ll = strtoll_l(__a, &__p2, __base, _LIBCPP_GET_C_LOCALE);
> +        long long __ll = strtoll(__a, &__p2, __base);
>          typename remove_reference<decltype(errno)>::type __current_errno = errno;
>          if (__current_errno == 0)
>              errno = __save_errno;
> @@ -869,7 +869,7 @@
>          typename remove_reference<decltype(errno)>::type __save_errno = errno;
>          errno = 0;
>          char *__p2;
> -        unsigned long long __ll = strtoull_l(__a, &__p2, __base, _LIBCPP_GET_C_LOCALE);
> +        unsigned long long __ll = strtoull(__a, &__p2, __base);
>          typename remove_reference<decltype(errno)>::type __current_errno = errno;
>          if (__current_errno == 0)
>              errno = __save_errno;
> @@ -899,7 +899,7 @@
>          typename remove_reference<decltype(errno)>::type __save_errno = errno;
>          errno = 0;
>          char *__p2;
> -        long double __ld = strtold_l(__a, &__p2, _LIBCPP_GET_C_LOCALE);
> +        long double __ld = strtold(__a, &__p2);
>          typename remove_reference<decltype(errno)>::type __current_errno = errno;
>          if (__current_errno == 0)
>              errno = __save_errno;
> Index: src/locale.cpp
> ===================================================================
> --- src/locale.cpp    (revision 190843)
> +++ src/locale.cpp    (working copy)
> @@ -1005,6 +1005,8 @@
>  extern "C" const int ** __ctype_toupper_loc();
>  #endif
>  
> +extern "C" const unsigned short ** __ctype_b_loc();
> +
>  const ctype<char>::mask*
>  ctype<char>::classic_table()  _NOEXCEPT
>  {
> @@ -1027,10 +1029,11 @@
>  #else
>      // Platform not supported: abort so the person doing the port knows what to
>      // fix
> -# warning  ctype<char>::classic_table() is not implemented
> -    printf("ctype<char>::classic_table() is not implemented\n");
> -    abort();
> -    return NULL;
> +//# warning  ctype<char>::classic_table() is not implemented
> +    //printf("ctype<char>::classic_table() is not implemented\n");
> +    //abort();
> +    //return NULL;
> +    return *__ctype_b_loc();
>  #endif
>  }
> 
> Did I miss anything in the patch ?
> 
> Thanks
> Yao
>  
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