[libcxx] r198505 - Switch to using C++ style casts.

[Alp Toker]

On 04/01/2014 17:43, Joerg Sonnenberger wrote:
> Modified: libcxx/trunk/src/stdexcept.cpp
> URL:http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/stdexcept.cpp?rev=198505&r1=198504&r2=198505&view=diff
> ==============================================================================
> --- libcxx/trunk/src/stdexcept.cpp (original)
> +++ libcxx/trunk/src/stdexcept.cpp Sat Jan  4 11:43:00 2014
> @@ -46,7 +46,7 @@ private:
>       static const std::ptrdiff_t offset = static_cast<std::ptrdiff_t>(2*sizeof(unused_t) +
>                                                                          sizeof(count_t));
>   
> -    count_t& count() const_NOEXCEPT {return (count_t&)(*(str_  - sizeof(count_t)));}
> +    count_t& count() const_NOEXCEPT {return *const_cast<count_t *>(reinterpret_cast<const count_t *>(str_  - sizeof(count_t)));}
>   public:
>       explicit __libcpp_nmstr(const char* msg);
>       __libcpp_nmstr(const __libcpp_nmstr& s) _NOEXCEPT;
> @@ -59,7 +59,7 @@ __libcpp_nmstr::__libcpp_nmstr(const cha
>   {
>       std::size_t len = strlen(msg);
>       str_ = new char[len + 1 + offset];
> -    unused_t* c = (unused_t*)str_;
> +    unused_t* c = reinterpret_cast<unused_t*>(const_cast<char *>(str_));
>       c[0] = c[1] = len;
>       str_ += offset;
>       count() = 0;
> @@ -79,7 +79,7 @@ __libcpp_nmstr::operator=(const __libcpp
>       const char* p = str_;
>       str_ = s.str_;
>       __sync_add_and_fetch(&count(), 1);
> -    if (__sync_add_and_fetch((count_t*)(p-sizeof(count_t)), count_t(-1)) < 0)
> +    if (__sync_add_and_fetch(reinterpret_cast<const count_t*>(p-sizeof(count_t)), count_t(-1)) < 0)

Hi Joerg,

The above change doesn't work with g++ (4.8.2).

llvm/projects/libcxx/src/stdexcept.cpp:82:94: error: invalid conversion 
from ‘const void*’ to ‘volatile void*’ [-fpermissive]
if (__sync_add_and_fetch(reinterpret_cast<const 
count_t*>(p-sizeof(count_t)), count_t(-1)) < 0)

Presumably it's because the gcc builtin has a slightly different 
parameter specification to the one in clang.

Changing this instance back to a C-style cast fixed the LLVM build 
locally. Should be possible to get it done with C++ casts too.

(This isn't a high priority build configuration for us, but the tree is 
still meant to be buildable with gcc AFAIK.)

Alp.



>           delete [] (p-offset);
>       return *this;
>   }
> @@ -102,28 +102,29 @@ namespace std  // purposefully not using
>   
>   logic_error::logic_error(const string& msg)
>   {
> -    __libcpp_nmstr& s = (__libcpp_nmstr&)__imp_;
> -    ::new(&s) __libcpp_nmstr(msg.c_str());
> +    __libcpp_nmstr *s = static_cast<__libcpp_nmstr *>(__imp_);
> +    ::new(s) __libcpp_nmstr(msg.c_str());
>   }
>   
>   logic_error::logic_error(const char* msg)
>   {
> -    __libcpp_nmstr& s = (__libcpp_nmstr&)__imp_;
> -    ::new(&s) __libcpp_nmstr(msg);
> +    __libcpp_nmstr *s = static_cast<__libcpp_nmstr *>(__imp_);
> +    ::new(s) __libcpp_nmstr(msg);
>   }
>   
>   logic_error::logic_error(const logic_error& le) _NOEXCEPT
>   {
> -    __libcpp_nmstr& s = (__libcpp_nmstr&)__imp_;
> -    ::new(&s) __libcpp_nmstr((const __libcpp_nmstr&)le.__imp_);
> +    __libcpp_nmstr *s = static_cast<__libcpp_nmstr *>(__imp_);
> +    const __libcpp_nmstr *s2 = static_cast<const __libcpp_nmstr *>(le.__imp_);
> +    ::new(s) __libcpp_nmstr(*s2);
>   }
>   

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