PR libstdc++/86398 fix std::is_trivially_constructible regression

The intrinsic doesn't check for allowed conversions between scalar
types, so restore the std::is_constructible check.

Also make some trivial whitespace changes.

	PR libstdc++/86398
	* include/std/type_traits (is_trivially_constructible): Check
	is_constructible before __is_trivially_constructible.
	* testsuite/20_util/is_trivially_constructible/value.cc: Add more
	tests, including negative cases.
	* testsuite/20_util/make_signed/requirements/typedefs_neg.cc: Use
	zero for dg-error lineno.
	* testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc:
	Likewise.

From-SVN: r262379

libstdc++-v3/ChangeLog

 2018-07-04  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/86398
+	* include/std/type_traits (is_trivially_constructible): Check
+	is_constructible before __is_trivially_constructible.
+	* testsuite/20_util/is_trivially_constructible/value.cc: Add more
+	tests, including negative cases.
+	* testsuite/20_util/make_signed/requirements/typedefs_neg.cc: Use
+	zero for dg-error lineno.
+	* testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc:
+	Likewise.
+
 	* include/std/bit (__rotl, __rotr): Avoid branch.
 	(_If_is_unsigned_integer): Use remove_cv_t.
 	* testsuite/26_numerics/bit/bitops.count/popcount.cc: New.

libstdc++-v3/include/std/type_traits

@@ -1136,7 +1136,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// is_trivially_constructible
   template<typename _Tp, typename... _Args>
     struct is_trivially_constructible
-    : public __bool_constant<__is_trivially_constructible(_Tp, _Args...)>
+    : public __and_<is_constructible<_Tp, _Args...>, __bool_constant<
+		      __is_trivially_constructible(_Tp, _Args...)>>::type
     { };
 
   /// is_trivially_default_constructible
@@ -1159,21 +1160,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   template<typename _Tp>
     struct __is_implicitly_default_constructible_impl
-      : public __do_is_implicitly_default_constructible_impl
-  {
-    typedef decltype(__test(declval<_Tp>())) type;
-  };
+    : public __do_is_implicitly_default_constructible_impl
+    {
+      typedef decltype(__test(declval<_Tp>())) type;
+    };
 
   template<typename _Tp>
     struct __is_implicitly_default_constructible_safe
-      : public __is_implicitly_default_constructible_impl<_Tp>::type
-  { };
+    : public __is_implicitly_default_constructible_impl<_Tp>::type
+    { };
 
   template <typename _Tp>
     struct __is_implicitly_default_constructible
-      : public __and_<is_default_constructible<_Tp>,
-                      __is_implicitly_default_constructible_safe<_Tp>>
-  { };
+    : public __and_<is_default_constructible<_Tp>,
+		    __is_implicitly_default_constructible_safe<_Tp>>
+    { };
 
   /// is_trivially_copy_constructible
 

libstdc++-v3/testsuite/20_util/make_signed/requirements/typedefs_neg.cc

@@ -47,4 +47,4 @@ void test01()
 // { dg-error "required from here" "" { target *-*-* } 39 }
 // { dg-error "required from here" "" { target *-*-* } 41 }
 
-// { dg-error "invalid use of incomplete type" "" { target *-*-* } 1825 }
+// { dg-error "invalid use of incomplete type" "" { target *-*-* } 0 }

libstdc++-v3/testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc

@@ -47,5 +47,4 @@ void test01()
 // { dg-error "required from here" "" { target *-*-* } 39 }
 // { dg-error "required from here" "" { target *-*-* } 41 }
 
-// { dg-error "invalid use of incomplete type" "" { target *-*-* } 1708 }
-
+// { dg-error "invalid use of incomplete type" "" { target *-*-* } 0 }