[cfe-commits] [PATCH] mutex: unify __mutex_base constructors

[Howard Hinnant]

On Dec 10, 2012, at 2:50 AM, Saleem Abdulrasool <compnerd at compnerd.org> wrote:

> Use the _LIBCPP_CONSTEXPR macro to allow the preprocessor to determine if
> constexpr should be applied to the constructor.  This is required to unify the
> constructor definition.
> 
> Unify the constructor declarations, moving the member variable initialisation
> into the initialiser-list.  This requires an ugly C-style cast to ensure
> portability across all implementations.  PTHREAD_{MUTEX,COND}_INITIALIZER may be
> an aggregate initialiser, which requires an explicit type conversion for the
> compound literal.
> 
> http://llvm-reviews.chandlerc.com/D194
> 
> Files:
>  include/__mutex_base
> 
> Index: include/__mutex_base
> ===================================================================
> --- include/__mutex_base
> +++ include/__mutex_base
> @@ -37,13 +37,9 @@
>     pthread_mutex_t __m_;
> 
> public:
> -    _LIBCPP_INLINE_VISIBILITY
> -#ifndef _LIBCPP_HAS_NO_CONSTEXPR
> -     constexpr mutex() _NOEXCEPT : __m_(PTHREAD_MUTEX_INITIALIZER) {}
> -#else
> -     mutex() _NOEXCEPT {__m_ = (pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER;}
> -#endif
> -     ~mutex();
> +    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR mutex() _NOEXCEPT
> +        : __m_((pthread_mutex_t)PTHREAD_MUTEX_INITIALIZER) {}
> +    ~mutex();
> 
> private:
>     mutex(const mutex&);// = delete;
> @@ -303,12 +299,8 @@
> {
>     pthread_cond_t __cv_;
> public:
> -    _LIBCPP_INLINE_VISIBILITY
> -#ifndef _LIBCPP_HAS_NO_CONSTEXPR
> -    constexpr condition_variable() : __cv_(PTHREAD_COND_INITIALIZER) {}
> -#else
> -    condition_variable() {__cv_ = (pthread_cond_t)PTHREAD_COND_INITIALIZER;}
> -#endif
> +    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR condition_variable()
> +        : __cv_((pthread_cond_t)PTHREAD_COND_INITIALIZER) {}
>     ~condition_variable();
> 
> private:
> <D194.1.patch>_______________________________________________
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Is this change just for stylistic reasons, or is it required to get something working?

Howard