libstdc++: Avoid redundant checks in std::use_facet [PR103755]

We do not need to do bounds checks or a runtime dynamic_cast when using
std::has_facet and std::use_facet to access the default facets that are
guaranteed to be present in every std::locale object. We can just index
straight into the array and use a static_cast for the conversion.

This patch adds a new std::__try_use_facet function that is like
std::use_facet but returns a pointer, so can be used to implement both
std::has_facet and std::use_facet. We can then do the necessary
metaprogramming to skip the redundant checks in std::__try_use_facet.

To avoid having to export (or hide) instantiations of the new function
from libstdc++.so the instantiations are given hidden visibility. This
allows them to be used in the library, but user code will instantiate it
again using the definition in the header. That would happen anyway,
because there are no explicit instantiation declarations for any of
std::has_facet, std::use_facet, or the new std::__try_use_facet.

libstdc++-v3/ChangeLog:

	PR libstdc++/103755
	* config/abi/pre/gnu.ver: Tighten patterns for facets in the
	base version. Add exports for __try_use_facet.
	* include/bits/basic_ios.tcc (basic_ios::_M_cache_locale): Use
	__try_use_facet instead of has_facet and use_facet.
	* include/bits/fstream.tcc (basic_filebuf::basic_filebuf()):
	Likewise.
	(basic_filebuf::imbue): Likewise.
	* include/bits/locale_classes.h (locale, locale::id)
	(locale::_Impl): Declare __try_use_facet as a friend.
	* include/bits/locale_classes.tcc (__try_use_facet): Define new
	function template with special cases for default facets.
	(has_facet, use_facet): Call __try_use_facet.
	* include/bits/locale_facets.tcc (__try_use_facet): Declare
	explicit instantiations.
	* include/bits/locale_facets_nonio.tcc (__try_use_facet):
	Likewise.
	* src/c++11/locale-inst-monetary.h (INSTANTIATE_FACET_ACCESSORS):
	Use new macro for facet accessor instantiations.
	* src/c++11/locale-inst-numeric.h (INSTANTIATE_FACET_ACCESSORS):
	Likewise.
	* src/c++11/locale-inst.cc (INSTANTIATE_USE_FACET): Define new
	macro for instantiating __try_use_facet and use_facet.
	(INSTANTIATE_FACET_ACCESSORS): Define new macro for also
	defining has_facet.
	* src/c++98/compatibility-ldbl.cc (__try_use_facet):
	Instantiate.
	* testsuite/22_locale/ctype/is/string/89728_neg.cc: Adjust
	expected errors.

12 files changed, 276 insertions, 135 deletions

diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 4d97ec3..225d6dc 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -133,17 +133,18 @@ GLIBCXX_3.4 {
 #     std::logic_error::~l*;
 #     std::[m-r]*;
 #     std::[m]*;
-      std::messages[^_]*;
+#     std::messages[^_]*;
 #     std::messages_byname*;
-      std::money_*;
-      std::moneypunct[^_]*;
+#     std::money_*;
+      std::money_base*;
+#     std::moneypunct[^_]*;
 #     std::moneypunct_byname*;
 #     std::n[^u]*;
       std::n[^aueo]*;
       std::nothrow;
       std::nu[^m]*;
-      std::num[^ep]*;
-      std::numpunct[^_]*;
+      std::num[^_ep]*;
+#     std::numpunct[^_]*;
 #     std::numpunct_byname*;
       std::ostrstream*;
 #     std::out_of_range::o*;
@@ -597,28 +598,49 @@ GLIBCXX_3.4 {
     _ZNSt12ctype_bynameI[cw]ED*;
 
     # std::num_get
+    _ZNSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[CD][012]*;
+    _ZNSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE2idE;
     _ZNKSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[2-9]*;
     _ZNKSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE14_M_extract_intI*;
-    _ZNKSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE16_M_extract_floatI*;
+    _ZNKSt7num_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE16_M_extract_float*;
 
     # std::num_put
+    _ZNSt7num_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[CD][012]*;
+    _ZNSt7num_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE2idE;
     _ZNKSt7num_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[2-9]*;
     _ZNKSt7num_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE1[234]*;
     _ZNKSt7num_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE15_M_insert_floatI*;
 
+    # std::numpunct
+    _ZNSt8numpunctI[cw]E[CD][012]*;
+    _ZNSt8numpunctI[cw]E2idE;
+    _ZNSt8numpunctI[cw]E[2]*;
+    _ZNKSt8numpunctI[cw]E[189]*;
+
     # std::numpunct_byname
     _ZNSt15numpunct_bynameI[cw]EC[12]EPKc[jmy];
     _ZNSt15numpunct_bynameI[cw]ED*;
 
     # std::money_get
+    _ZNSt9money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[CD][012]*;
+    _ZNSt9money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE2idE;
     _ZNKSt9money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[2-9]*;
     _ZNKSt9money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEE10_M_extractILb[01]EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs;
 
     # std::money_put
+    _ZNSt9money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[CD][012]*;
+    _ZNSt9money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE2idE;
     _ZNKSt9money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE[1-8]*;
     _ZNKSt9money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb[01]EEES3_S3_RSt8ios_basecRKSs;
     _ZNKSt9money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb[01]EEES3_S3_RSt8ios_basewRKSbIwS2_SaIwEE;
 
+    # std::moneypunct
+    _ZNSt10moneypunctI[cw]Lb[01]EE[CD][012]*;
+    _ZNSt10moneypunctI[cw]Lb[01]EE2idE;
+    _ZNSt10moneypunctI[cw]Lb[01]EE24*;
+    _ZNSt10moneypunctI[cw]Lb[01]EE4intlE;
+    _ZNKSt10moneypunctI[cw]Lb[01]EE[18]*;
+
     # std::moneypunct_byname
     _ZNSt17moneypunct_bynameI[cw]Lb[01]EEC[12]EPKc[jmy];
     _ZNSt17moneypunct_bynameI[cw]Lb[01]EED*;
@@ -657,6 +679,11 @@ GLIBCXX_3.4 {
     _ZNSt14numeric_limitsI[a-m]E1[0-7]max_e*;
     _ZNSt14numeric_limitsI[p-z]E1[0-7]max_e*;
 
+    # std::messages
+    _ZNSt8messagesI[cw]E[CD][012]*;
+    _ZNSt8messagesI[cw]E2idE;
+    _ZNKSt8messagesI[cw]E[1-8]*;
+
     # std::messages_byname
     _ZNSt15messages_bynameI[cw]EC[12]EPKc[jmy];
     _ZNSt15messages_bynameI[cw]ED*;
@@ -2446,6 +2473,7 @@ GLIBCXX_3.4.30 {
 
 GLIBCXX_3.4.31 {
     _ZNSt7__cxx1112basic_stringI[cw]St11char_traitsI[cw]ESaI[cw]EE15_M_replace_cold*;
+
     _ZSt20__to_chars_float16_tPcS_fSt12chars_format;
     _ZSt21__to_chars_bfloat16_tPcS_fSt12chars_format;
     _ZSt22__from_chars_float16_tPKcS0_RfSt12chars_format;
@@ -2454,6 +2482,9 @@ GLIBCXX_3.4.31 {
     _ZSt8to_charsPcS_DF128_St12chars_format;
     _ZSt8to_charsPcS_DF128_St12chars_formati;
     _ZSt10from_charsPKcS0_RDF128_St12chars_format;
+
+    _ZSt15__try_use_facet*;
+
 } GLIBCXX_3.4.30;
 
 # Symbols in the support library (libsupc++) have their own tag.
diff --git a/libstdc++-v3/include/bits/basic_ios.tcc b/libstdc++-v3/include/bits/basic_ios.tcc
index 2bbcdc2..15d35a4 100644
--- a/libstdc++-v3/include/bits/basic_ios.tcc
+++ b/libstdc++-v3/include/bits/basic_ios.tcc
@@ -156,20 +156,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     void
     basic_ios<_CharT, _Traits>::_M_cache_locale(const locale& __loc)
     {
-      if (__builtin_expect(has_facet<__ctype_type>(__loc), true))
-	_M_ctype = std::__addressof(use_facet<__ctype_type>(__loc));
-      else
-	_M_ctype = 0;
-
-      if (__builtin_expect(has_facet<__num_put_type>(__loc), true))
-	_M_num_put = std::__addressof(use_facet<__num_put_type>(__loc));
-      else
-	_M_num_put = 0;
-
-      if (__builtin_expect(has_facet<__num_get_type>(__loc), true))
-	_M_num_get = std::__addressof(use_facet<__num_get_type>(__loc));
-      else
-	_M_num_get = 0;
+      _M_ctype = std::__try_use_facet<__ctype_type>(__loc);
+      _M_num_put = std::__try_use_facet<__num_put_type>(__loc);
+      _M_num_get = std::__try_use_facet<__num_get_type>(__loc);
     }
 
   // Inhibit implicit instantiations for required instantiations,
diff --git a/libstdc++-v3/include/bits/fstream.tcc b/libstdc++-v3/include/bits/fstream.tcc
index 2e93696..8158ab3 100644
--- a/libstdc++-v3/include/bits/fstream.tcc
+++ b/libstdc++-v3/include/bits/fstream.tcc
@@ -86,8 +86,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
     _M_ext_end(0)
     {
-      if (has_facet<__codecvt_type>(this->_M_buf_locale))
-	_M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
+      _M_codecvt = std::__try_use_facet<__codecvt_type>(this->_M_buf_locale);
     }
 
 #if __cplusplus >= 201103L
@@ -1028,9 +1027,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     {
       bool __testvalid = true;
 
-      const __codecvt_type* _M_codecvt_tmp = 0;
-      if (__builtin_expect(has_facet<__codecvt_type>(__loc), true))
-	_M_codecvt_tmp = &use_facet<__codecvt_type>(__loc);
+      const __codecvt_type* const _M_codecvt_tmp
+	= __try_use_facet<__codecvt_type>(__loc);
 
       if (this->is_open())
 	{
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index 6cad0ff..6912a54 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -82,6 +82,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       friend const _Facet&
       use_facet(const locale&);
 
+    template<typename _Facet>
+      friend const _Facet*
+      __try_use_facet(const locale&) _GLIBCXX_NOTHROW;
+
     template<typename _Cache>
       friend struct __use_cache;
 
@@ -496,6 +500,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       friend bool
       has_facet(const locale&) throw();
 
+    template<typename _Facet>
+      friend const _Facet*
+      __try_use_facet(const locale&) _GLIBCXX_NOTHROW;
+
     // NB: There is no accessor for _M_index because it may be used
     // before the constructor is run; the effect of calling a member
     // function (even an inline) would be undefined.
@@ -536,6 +544,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       friend const _Facet&
       use_facet(const locale&);
 
+    template<typename _Facet>
+      friend const _Facet*
+      __try_use_facet(const locale&) _GLIBCXX_NOTHROW;
+
     template<typename _Cache>
       friend struct __use_cache;
 
diff --git a/libstdc++-v3/include/bits/locale_classes.tcc b/libstdc++-v3/include/bits/locale_classes.tcc
index 9cc4f23..7a67f5c 100644
--- a/libstdc++-v3/include/bits/locale_classes.tcc
+++ b/libstdc++-v3/include/bits/locale_classes.tcc
@@ -87,6 +87,68 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 				__s2.data(), __s2.data() + __s2.length()) < 0);
     }
 
+  template<typename _Facet>
+    inline const _Facet*
+    __try_use_facet(const locale& __loc) _GLIBCXX_NOTHROW
+    {
+      const size_t __i = _Facet::id._M_id();
+      const locale::facet** __facets = __loc._M_impl->_M_facets;
+
+      // We know these standard facets are always installed in every locale
+      // so dynamic_cast always succeeds, just use static_cast instead.
+#define _GLIBCXX_STD_FACET(...) \
+      if _GLIBCXX17_CONSTEXPR (__is_same(_Facet, __VA_ARGS__)) \
+	return static_cast<const _Facet*>(__facets[__i])
+
+      _GLIBCXX_STD_FACET(ctype<char>);
+      _GLIBCXX_STD_FACET(num_get<char>);
+      _GLIBCXX_STD_FACET(num_put<char>);
+      _GLIBCXX_STD_FACET(codecvt<char, char, mbstate_t>);
+      _GLIBCXX_STD_FACET(collate<char>);
+      _GLIBCXX_STD_FACET(moneypunct<char>);
+      _GLIBCXX_STD_FACET(moneypunct<char, true>);
+      _GLIBCXX_STD_FACET(money_get<char>);
+      _GLIBCXX_STD_FACET(money_put<char>);
+      _GLIBCXX_STD_FACET(numpunct<char>);
+      _GLIBCXX_STD_FACET(time_get<char>);
+      _GLIBCXX_STD_FACET(time_put<char>);
+      _GLIBCXX_STD_FACET(messages<char>);
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+      _GLIBCXX_STD_FACET(ctype<wchar_t>);
+      _GLIBCXX_STD_FACET(num_get<wchar_t>);
+      _GLIBCXX_STD_FACET(num_put<wchar_t>);
+      _GLIBCXX_STD_FACET(codecvt<wchar_t, char, mbstate_t>);
+      _GLIBCXX_STD_FACET(collate<wchar_t>);
+      _GLIBCXX_STD_FACET(moneypunct<wchar_t>);
+      _GLIBCXX_STD_FACET(moneypunct<wchar_t, true>);
+      _GLIBCXX_STD_FACET(money_get<wchar_t>);
+      _GLIBCXX_STD_FACET(money_put<wchar_t>);
+      _GLIBCXX_STD_FACET(numpunct<wchar_t>);
+      _GLIBCXX_STD_FACET(time_get<wchar_t>);
+      _GLIBCXX_STD_FACET(time_put<wchar_t>);
+      _GLIBCXX_STD_FACET(messages<wchar_t>);
+#endif
+#ifdef _GLIBCXX_USE_CHAR8_T
+      _GLIBCXX_STD_FACET(codecvt<char8_t, char, mbstate_t>);
+#endif
+#if __cplusplus >= 201103L
+      _GLIBCXX_STD_FACET(codecvt<char16_t, char, mbstate_t>);
+      _GLIBCXX_STD_FACET(codecvt<char32_t, char, mbstate_t>);
+#endif
+
+#undef _GLIBCXX_STD_FACET
+
+      if (__i >= __loc._M_impl->_M_facets_size || !__facets[__i])
+	return 0;
+
+#if __cpp_rtti
+      return dynamic_cast<const _Facet*>(__facets[__i]);
+#else
+      return static_cast<const _Facet*>(__facets[__i]);
+#endif
+    }
+
   /**
    *  @brief  Test for the presence of a facet.
    *  @ingroup locales
@@ -100,17 +162,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  @return  true if @p __loc contains a facet of type _Facet, else false.
   */
   template<typename _Facet>
-    bool
+    inline bool
     has_facet(const locale& __loc) throw()
     {
-      const size_t __i = _Facet::id._M_id();
-      const locale::facet** __facets = __loc._M_impl->_M_facets;
-      return (__i < __loc._M_impl->_M_facets_size
-#if __cpp_rtti
-	      && dynamic_cast<const _Facet*>(__facets[__i]));
+#if __cplusplus >= 201103L
+      static_assert(__is_base_of(locale::facet, _Facet),
+		    "template argument must be derived from locale::facet");
 #else
-              && static_cast<const _Facet*>(__facets[__i]));
+      (void) static_cast<const _Facet*>(static_cast<const locale::facet*>(0));
 #endif
+      return std::__try_use_facet<_Facet>(__loc) != 0;
     }
 
   /**
@@ -130,18 +191,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdangling-reference"
   template<typename _Facet>
-    const _Facet&
+    inline const _Facet&
     use_facet(const locale& __loc)
     {
-      const size_t __i = _Facet::id._M_id();
-      const locale::facet** __facets = __loc._M_impl->_M_facets;
-      if (__i >= __loc._M_impl->_M_facets_size || !__facets[__i])
-        __throw_bad_cast();
-#if __cpp_rtti
-      return dynamic_cast<const _Facet&>(*__facets[__i]);
+#if __cplusplus >= 201103L
+      static_assert(__is_base_of(locale::facet, _Facet),
+		    "template argument must be derived from locale::facet");
 #else
-      return static_cast<const _Facet&>(*__facets[__i]);
+      (void) static_cast<const _Facet*>(static_cast<const locale::facet*>(0));
 #endif
+      if (const _Facet* __f = std::__try_use_facet<_Facet>(__loc))
+	return *__f;
+      __throw_bad_cast();
     }
 #pragma GCC diagnostic pop
 
@@ -274,6 +335,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   extern template class collate_byname<char>;
 
   extern template
+    const collate<char>*
+    __try_use_facet<collate<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const collate<char>&
     use_facet<collate<char> >(const locale&);
 
@@ -286,6 +351,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   extern template class collate_byname<wchar_t>;
 
   extern template
+    const collate<wchar_t>*
+    __try_use_facet<collate<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const collate<wchar_t>&
     use_facet<collate<wchar_t> >(const locale&);
 
diff --git a/libstdc++-v3/include/bits/locale_facets.tcc b/libstdc++-v3/include/bits/locale_facets.tcc
index ec7cce4..dd5c45e 100644
--- a/libstdc++-v3/include/bits/locale_facets.tcc
+++ b/libstdc++-v3/include/bits/locale_facets.tcc
@@ -1326,6 +1326,22 @@ _GLIBCXX_END_NAMESPACE_LDBL
   extern template class ctype_byname<char>;
 
   extern template
+    const ctype<char>*
+    __try_use_facet<ctype<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const numpunct<char>*
+    __try_use_facet<numpunct<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const num_put<char>*
+    __try_use_facet<num_put<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const num_get<char>*
+    __try_use_facet<num_get<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const ctype<char>&
     use_facet<ctype<char> >(const locale&);
 
@@ -1365,6 +1381,22 @@ _GLIBCXX_END_NAMESPACE_LDBL
   extern template class ctype_byname<wchar_t>;
 
   extern template
+    const ctype<wchar_t>*
+    __try_use_facet<ctype<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const numpunct<wchar_t>*
+    __try_use_facet<numpunct<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const num_put<wchar_t>*
+    __try_use_facet<num_put<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const num_get<wchar_t>*
+    __try_use_facet<num_get<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const ctype<wchar_t>&
     use_facet<ctype<wchar_t> >(const locale&);
 
@@ -1380,7 +1412,7 @@ _GLIBCXX_END_NAMESPACE_LDBL
     const num_get<wchar_t>&
     use_facet<num_get<wchar_t> >(const locale&);
 
- extern template
+  extern template
     bool
     has_facet<ctype<wchar_t> >(const locale&);
 
diff --git a/libstdc++-v3/include/bits/locale_facets_nonio.tcc b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
index 17a2c8d..320bcf2 100644
--- a/libstdc++-v3/include/bits/locale_facets_nonio.tcc
+++ b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
@@ -1692,6 +1692,38 @@ _GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11
   extern template class messages_byname<char>;
 
   extern template
+    const moneypunct<char, true>*
+    __try_use_facet<moneypunct<char, true> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const moneypunct<char, false>*
+    __try_use_facet<moneypunct<char, false> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const money_put<char>*
+    __try_use_facet<money_put<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const money_get<char>*
+    __try_use_facet<money_get<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const __timepunct<char>*
+    __try_use_facet<__timepunct<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const time_put<char>*
+    __try_use_facet<time_put<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const time_get<char>*
+    __try_use_facet<time_get<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const messages<char>*
+    __try_use_facet<messages<char> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const moneypunct<char, true>&
     use_facet<moneypunct<char, true> >(const locale&);
 
@@ -1767,6 +1799,38 @@ _GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11
   extern template class messages_byname<wchar_t>;
 
   extern template
+    const moneypunct<wchar_t, true>*
+    __try_use_facet<moneypunct<wchar_t, true> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const moneypunct<wchar_t, false>*
+    __try_use_facet<moneypunct<wchar_t, false> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const money_put<wchar_t>*
+    __try_use_facet<money_put<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const money_get<wchar_t>*
+    __try_use_facet<money_get<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const __timepunct<wchar_t>*
+    __try_use_facet<__timepunct<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const time_put<wchar_t>*
+    __try_use_facet<time_put<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const time_get<wchar_t>*
+    __try_use_facet<time_get<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
+    const messages<wchar_t>*
+    __try_use_facet<messages<wchar_t> >(const locale&) _GLIBCXX_NOTHROW;
+
+  extern template
     const moneypunct<wchar_t, true>&
     use_facet<moneypunct<wchar_t, true> >(const locale&);
 
diff --git a/libstdc++-v3/src/c++11/locale-inst-monetary.h b/libstdc++-v3/src/c++11/locale-inst-monetary.h
index e1c696d..ff84398 100644
--- a/libstdc++-v3/src/c++11/locale-inst-monetary.h
+++ b/libstdc++-v3/src/c++11/locale-inst-monetary.h
@@ -32,11 +32,9 @@
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {
-  template const money_put<C>& use_facet<money_put<C> >(const locale&);
-  template const money_get<C>& use_facet<money_get<C> >(const locale&);
-
-  template bool has_facet<money_put<C> >(const locale&);
-  template bool has_facet<money_get<C> >(const locale&);
+// use_facet and has_facet instantiations
+INSTANTIATE_FACET_ACCESSORS(money_put<C>);
+INSTANTIATE_FACET_ACCESSORS(money_get<C>);
 
 _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
   template class money_get<C, istreambuf_iterator<C> >;
diff --git a/libstdc++-v3/src/c++11/locale-inst-numeric.h b/libstdc++-v3/src/c++11/locale-inst-numeric.h
index 1417ac2..4b970f7 100644
--- a/libstdc++-v3/src/c++11/locale-inst-numeric.h
+++ b/libstdc++-v3/src/c++11/locale-inst-numeric.h
@@ -29,11 +29,9 @@
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 #if ! _GLIBCXX_USE_CXX11_ABI
-  template const num_get<C>& use_facet<num_get<C> >(const locale&);
-  template const num_put<C>& use_facet<num_put<C> >(const locale&);
-
-  template bool has_facet<num_get<C> >(const locale&);
-  template bool has_facet<num_put<C> >(const locale&);
+// use_facet and has_facet instantiations
+INSTANTIATE_FACET_ACCESSORS(num_get<C>);
+INSTANTIATE_FACET_ACCESSORS(num_put<C>);
 #endif
 
 _GLIBCXX_BEGIN_NAMESPACE_LDBL
diff --git a/libstdc++-v3/src/c++11/locale-inst.cc b/libstdc++-v3/src/c++11/locale-inst.cc
index 3aee5df..b264cb3 100644
--- a/libstdc++-v3/src/c++11/locale-inst.cc
+++ b/libstdc++-v3/src/c++11/locale-inst.cc
@@ -43,6 +43,17 @@
 # define C_is_char
 #endif
 
+#define INSTANTIATE_USE_FACET(...)			    \
+  template const __VA_ARGS__*				    \
+    __try_use_facet< __VA_ARGS__ >(const locale&) noexcept; \
+  template const __VA_ARGS__&				    \
+    use_facet<__VA_ARGS__>(const locale&)		    \
+
+#define INSTANTIATE_FACET_ACCESSORS(...)		    \
+  INSTANTIATE_USE_FACET(__VA_ARGS__);			    \
+  template bool						    \
+    has_facet<__VA_ARGS__>(const locale&) noexcept
+
 #include "locale-inst-numeric.h"
 #include "locale-inst-monetary.h"
 
@@ -116,92 +127,22 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
   template class collate_byname<C>;
 _GLIBCXX_END_NAMESPACE_CXX11
 
-  // use_facet
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    const ctype<C>&
-    use_facet<ctype<C> >(const locale&);
-
-  template
-    const codecvt<C, char, mbstate_t>&
-    use_facet<codecvt<C, char, mbstate_t> >(const locale&);
-#endif
-
-  template
-    const collate<C>&
-    use_facet<collate<C> >(const locale&);
-
-  template
-    const numpunct<C>&
-    use_facet<numpunct<C> >(const locale&);
-
-  template
-    const moneypunct<C, true>&
-    use_facet<moneypunct<C, true> >(const locale&);
-
-  template
-    const moneypunct<C, false>&
-    use_facet<moneypunct<C, false> >(const locale&);
-
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    const __timepunct<C>&
-    use_facet<__timepunct<C> >(const locale&);
-
-  template
-    const time_put<C>&
-    use_facet<time_put<C> >(const locale&);
-#endif
-
-  template
-    const time_get<C>&
-    use_facet<time_get<C> >(const locale&);
-
-  template
-    const messages<C>&
-    use_facet<messages<C> >(const locale&);
-
-  // has_facet
+// use_facet and has_facet instantiations
 #if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    bool
-    has_facet<ctype<C> >(const locale&);
-
-  template
-    bool
-    has_facet<codecvt<C, char, mbstate_t> >(const locale&);
+INSTANTIATE_FACET_ACCESSORS(ctype<C>);
+INSTANTIATE_FACET_ACCESSORS(codecvt<C, char, mbstate_t>);
 #endif
-
-  template
-    bool
-    has_facet<collate<C> >(const locale&);
-
-  template
-    bool
-    has_facet<numpunct<C> >(const locale&);
-
-  template
-    bool
-    has_facet<moneypunct<C> >(const locale&);
-
+INSTANTIATE_FACET_ACCESSORS(collate<C>);
+INSTANTIATE_FACET_ACCESSORS(numpunct<C>);
+INSTANTIATE_FACET_ACCESSORS(moneypunct<C, false>);
+// No explicit instantiation of has_facet<moneypunct<C, true>> for some reason.
+INSTANTIATE_USE_FACET      (moneypunct<C, true>);
 #if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    bool
-    has_facet<__timepunct<C> >(const locale&);
-
-  template
-    bool
-    has_facet<time_put<C> >(const locale&);
+INSTANTIATE_FACET_ACCESSORS(__timepunct<C>);
+INSTANTIATE_FACET_ACCESSORS(time_put<C>);
 #endif
-
-  template
-    bool
-    has_facet<time_get<C> >(const locale&);
-
-  template
-    bool
-    has_facet<messages<C> >(const locale&);
-
+INSTANTIATE_FACET_ACCESSORS(time_get<C>);
+INSTANTIATE_FACET_ACCESSORS(messages<C>);
 
 #if ! _GLIBCXX_USE_CXX11_ABI
   // locale functions.
diff --git a/libstdc++-v3/src/c++98/compatibility-ldbl.cc b/libstdc++-v3/src/c++98/compatibility-ldbl.cc
index 683f7a8..55a5943 100644
--- a/libstdc++-v3/src/c++98/compatibility-ldbl.cc
+++ b/libstdc++-v3/src/c++98/compatibility-ldbl.cc
@@ -48,6 +48,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
   template bool has_facet<num_get<C> >(const locale&);
   template bool has_facet<money_put<C> >(const locale&);
   template bool has_facet<money_get<C> >(const locale&);
+  template const num_put<C>* __try_use_facet<num_put<C> >(const locale&);
+  template const num_get<C>* __try_use_facet<num_get<C> >(const locale&);
+  template const money_put<C>* __try_use_facet<money_put<C> >(const locale&);
+  template const money_get<C>* __try_use_facet<money_get<C> >(const locale&);
 #undef C
 #ifdef _GLIBCXX_USE_WCHAR_T
 #define C wchar_t
@@ -63,6 +67,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
   template bool has_facet<num_get<C> >(const locale&);
   template bool has_facet<money_put<C> >(const locale&);
   template bool has_facet<money_get<C> >(const locale&);
+  template const num_put<C>* __try_use_facet<num_put<C> >(const locale&);
+  template const num_get<C>* __try_use_facet<num_get<C> >(const locale&);
+  template const money_put<C>* __try_use_facet<money_put<C> >(const locale&);
+  template const money_get<C>* __try_use_facet<money_get<C> >(const locale&);
 #undef C
 #endif
 }
diff --git a/libstdc++-v3/testsuite/22_locale/ctype/is/string/89728_neg.cc b/libstdc++-v3/testsuite/22_locale/ctype/is/string/89728_neg.cc
index 7935c99..047df40e 100644
--- a/libstdc++-v3/testsuite/22_locale/ctype/is/string/89728_neg.cc
+++ b/libstdc++-v3/testsuite/22_locale/ctype/is/string/89728_neg.cc
@@ -17,14 +17,15 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// { dg-error "complete" "" { target *-*-* } 0 }
-// { dg-error "invalid 'static_cast'" "" { target { ! rtti }  } 0 }
+// { dg-error "invalid use of incomplete type" "" { target *-*-* } 0 }
+// { dg-error "invalid 'static_cast'" "" { target c++98_only } 0 }
 
 #include <locale>
 
 template <class Char, int I>
 struct trait: std::char_traits<Char> {};
 
+// Generates unique types so we get distinct diagnostics for each line.
 template <class Char, int I>
 std::basic_string<Char, trait<Char, I> > make_str()
 {