re PR libstdc++/53578 (include/ext/concurrence.h relies on ill-formed narrowing conversions)

	PR libstdc++/53578
	* include/ext/concurrence.h (__recursive_mutex::_S_destroy): Fix
	narrowing conversion.
	* include/std/mutex (__recursive_mutex_base::_S_destroy): Likewise.

From-SVN: r188646

libstdc++-v3/ChangeLog

+2012-06-15  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	PR libstdc++/53578
+	* include/ext/concurrence.h (__recursive_mutex::_S_destroy): Fix
+	narrowing conversion.
+	* include/std/mutex (__recursive_mutex_base::_S_destroy): Likewise.
+
 2012-06-14  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	PR libstdc++/53270

libstdc++-v3/include/ext/concurrence.h

@@ -284,7 +284,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     // matches a gthr-win32.h recursive mutex
     template<typename _Rm>
-      static typename __enable_if<sizeof(&_Rm::sema), void>::__type
+      static typename __enable_if<(bool)sizeof(&_Rm::sema), void>::__type
       _S_destroy(_Rm* __mx)
       {
         __gthread_mutex_t __tmp;
@@ -293,7 +293,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     // matches a recursive mutex with a member 'actual'
     template<typename _Rm>
-      static typename __enable_if<sizeof(&_Rm::actual), void>::__type
+      static typename __enable_if<(bool)sizeof(&_Rm::actual), void>::__type
       _S_destroy(_Rm* __mx)
       { __gthread_mutex_destroy(&__mx->actual); }
 

libstdc++-v3/include/std/mutex

@@ -116,13 +116,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     // matches a recursive mutex with a member 'actual'
     template<typename _Rm>
-      static typename enable_if<sizeof(&_Rm::actual), void>::type
+      static typename enable_if<(bool)sizeof(&_Rm::actual), void>::type
       _S_destroy(_Rm* __mx)
       { __gthread_mutex_destroy(&__mx->actual); }
 
     // matches a gthr-win32.h recursive mutex
     template<typename _Rm>
-      static typename enable_if<sizeof(&_Rm::sema), void>::type
+      static typename enable_if<(bool)sizeof(&_Rm::sema), void>::type
       _S_destroy(_Rm* __mx)
       {
         __gthread_mutex_t __tmp;