libstdc++: Populate std::time_get::get's %c format for C locale

We were using the empty string "" for D_T_FMT and ERA_D_T_FMT in the C
locale, instead of "%a %b %e %T %Y" as the C standard requires. Set it
correctly for each locale implementation that defines time_members.cc.

We can also explicitly set the _M_era_xxx pointers to the same values as
the corresponding _M_xxx ones, rather than setting them to point to
identical string literals. This doesn't rely on the compiler merging
string literals, and makes it more explicit that they're the same in the
C locale.

libstdc++-v3/ChangeLog:

	* config/locale/dragonfly/time_members.cc
	(__timepunct<char>::_M_initialize_timepunc)
	(__timepunct<wchar_t>::_M_initialize_timepunc): Set
	_M_date_time_format for C locale. Set %Ex formats to the same
	values as the %x formats.
	* config/locale/generic/time_members.cc: Likewise.
	* config/locale/gnu/time_members.cc: Likewise.
	* testsuite/22_locale/time_get/get/char/5.cc: New test.
	* testsuite/22_locale/time_get/get/wchar_t/5.cc: New test.

5 files changed, 94 insertions, 20 deletions

diff --git a/libstdc++-v3/config/locale/dragonfly/time_members.cc b/libstdc++-v3/config/locale/dragonfly/time_members.cc
index 0c96928..069b2dd 100644
--- a/libstdc++-v3/config/locale/dragonfly/time_members.cc
+++ b/libstdc++-v3/config/locale/dragonfly/time_members.cc
@@ -67,11 +67,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _M_c_locale_timepunct = _S_get_c_locale();
 
 	  _M_data->_M_date_format = "%m/%d/%y";
-	  _M_data->_M_date_era_format = "%m/%d/%y";
+	  _M_data->_M_date_era_format = _M_data->_M_date_format;
 	  _M_data->_M_time_format = "%H:%M:%S";
-	  _M_data->_M_time_era_format = "%H:%M:%S";
-	  _M_data->_M_date_time_format = "";
-	  _M_data->_M_date_time_era_format = "";
+	  _M_data->_M_time_era_format = _M_data->_M_time_format;
+	  _M_data->_M_date_time_format = "%a %b %e %T %Y";
+	  _M_data->_M_date_time_era_format = _M_data->_M_date_time_format;
 	  _M_data->_M_am = "AM";
 	  _M_data->_M_pm = "PM";
 	  _M_data->_M_am_pm_format = "%I:%M:%S %p";
@@ -224,11 +224,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _M_c_locale_timepunct = _S_get_c_locale();
 
 	  _M_data->_M_date_format = L"%m/%d/%y";
-	  _M_data->_M_date_era_format = L"%m/%d/%y";
+	  _M_data->_M_date_era_format = _M_data->_M_date_format;
 	  _M_data->_M_time_format = L"%H:%M:%S";
-	  _M_data->_M_time_era_format = L"%H:%M:%S";
-	  _M_data->_M_date_time_format = L"";
-	  _M_data->_M_date_time_era_format = L"";
+	  _M_data->_M_time_era_format = _M_data->_M_time_format;
+	  _M_data->_M_date_time_format = L"%a %b %e %T %Y";
+	  _M_data->_M_date_time_era_format = _M_data->_M_date_time_format;
 	  _M_data->_M_am = L"AM";
 	  _M_data->_M_pm = L"PM";
 	  _M_data->_M_am_pm_format = L"%I:%M:%S %p";
diff --git a/libstdc++-v3/config/locale/generic/time_members.cc b/libstdc++-v3/config/locale/generic/time_members.cc
index 6839582..6619f0c 100644
--- a/libstdc++-v3/config/locale/generic/time_members.cc
+++ b/libstdc++-v3/config/locale/generic/time_members.cc
@@ -65,11 +65,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	_M_data = new __timepunct_cache<char>;
 
       _M_data->_M_date_format = "%m/%d/%y";
-      _M_data->_M_date_era_format = "%m/%d/%y";
+      _M_data->_M_date_era_format = _M_data->_M_date_format;
       _M_data->_M_time_format = "%H:%M:%S";
-      _M_data->_M_time_era_format = "%H:%M:%S";
-      _M_data->_M_date_time_format = "";
-      _M_data->_M_date_time_era_format = "";
+      _M_data->_M_time_era_format = _M_data->_M_time_format;
+      _M_data->_M_date_time_format = "%a %b %e %T %Y";
+      _M_data->_M_date_time_era_format = _M_data->_M_date_time_format;
       _M_data->_M_am = "AM";
       _M_data->_M_pm = "PM";
       _M_data->_M_am_pm_format = "%I:%M:%S %p";
diff --git a/libstdc++-v3/config/locale/gnu/time_members.cc b/libstdc++-v3/config/locale/gnu/time_members.cc
index 1e3b874..88c8ab7 100644
--- a/libstdc++-v3/config/locale/gnu/time_members.cc
+++ b/libstdc++-v3/config/locale/gnu/time_members.cc
@@ -73,11 +73,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _M_c_locale_timepunct = _S_get_c_locale();
 
 	  _M_data->_M_date_format = "%m/%d/%y";
-	  _M_data->_M_date_era_format = "%m/%d/%y";
+	  _M_data->_M_date_era_format = _M_data->_M_date_format;
 	  _M_data->_M_time_format = "%H:%M:%S";
-	  _M_data->_M_time_era_format = "%H:%M:%S";
-	  _M_data->_M_date_time_format = "";
-	  _M_data->_M_date_time_era_format = "";
+	  _M_data->_M_time_era_format = _M_data->_M_time_format;
+	  _M_data->_M_date_time_format = "%a %b %e %T %Y";
+	  _M_data->_M_date_time_era_format = _M_data->_M_date_time_format;
 	  _M_data->_M_am = "AM";
 	  _M_data->_M_pm = "PM";
 	  _M_data->_M_am_pm_format = "%I:%M:%S %p";
@@ -229,11 +229,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  _M_c_locale_timepunct = _S_get_c_locale();
 
 	  _M_data->_M_date_format = L"%m/%d/%y";
-	  _M_data->_M_date_era_format = L"%m/%d/%y";
+	  _M_data->_M_date_era_format = _M_data->_M_date_format;
 	  _M_data->_M_time_format = L"%H:%M:%S";
-	  _M_data->_M_time_era_format = L"%H:%M:%S";
-	  _M_data->_M_date_time_format = L"";
-	  _M_data->_M_date_time_era_format = L"";
+	  _M_data->_M_time_era_format = _M_data->_M_time_format;
+	  _M_data->_M_date_time_format = L"%a %b %e %T %Y";
+	  _M_data->_M_date_time_era_format = _M_data->_M_date_time_format;
 	  _M_data->_M_am = L"AM";
 	  _M_data->_M_pm = L"PM";
 	  _M_data->_M_am_pm_format = L"%I:%M:%S %p";
diff --git a/libstdc++-v3/testsuite/22_locale/time_get/get/char/5.cc b/libstdc++-v3/testsuite/22_locale/time_get/get/char/5.cc
new file mode 100644
index 0000000..61fc329
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/time_get/get/char/5.cc
@@ -0,0 +1,37 @@
+// { dg-do run { target c++11} }
+
+#include <locale>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+int main()
+{
+  using Facet = std::time_get<char>;
+  const Facet& fac = std::use_facet<Facet>(std::locale::classic());
+  std::istringstream ss("Fri Jul 5 14:58:21 2019");
+  std::ios::iostate err = std::ios::goodbit;
+  std::tm tm = {};
+  fac.get(ss, Facet::iter_type(), ss, err, &tm, 'c');
+  VERIFY( err == std::ios::eofbit );
+  VERIFY( tm.tm_year == 119 );
+  VERIFY( tm.tm_mon == 6 );
+  VERIFY( tm.tm_mday == 5 );
+  VERIFY( tm.tm_wday == 5 );
+  VERIFY( tm.tm_hour == 14 );
+  VERIFY( tm.tm_min == 58 );
+  VERIFY( tm.tm_sec == 21 );
+  ss.clear();
+  ss.seekg(0);
+  ss.str(ss.str() + " non-whitespace after the datetime");
+  err = std::ios::goodbit;
+  tm = std::tm();
+  fac.get(ss, Facet::iter_type(), ss, err, &tm, 'c', 'E');
+  VERIFY( err == std::ios::goodbit );
+  VERIFY( tm.tm_year == 119 );
+  VERIFY( tm.tm_mon == 6 );
+  VERIFY( tm.tm_mday == 5 );
+  VERIFY( tm.tm_wday == 5 );
+  VERIFY( tm.tm_hour == 14 );
+  VERIFY( tm.tm_min == 58 );
+  VERIFY( tm.tm_sec == 21 );
+}
diff --git a/libstdc++-v3/testsuite/22_locale/time_get/get/wchar_t/5.cc b/libstdc++-v3/testsuite/22_locale/time_get/get/wchar_t/5.cc
new file mode 100644
index 0000000..5f350b0
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/time_get/get/wchar_t/5.cc
@@ -0,0 +1,37 @@
+// { dg-do run { target c++11} }
+
+#include <locale>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+int main()
+{
+  using Facet = std::time_get<wchar_t>;
+  const Facet& fac = std::use_facet<Facet>(std::locale::classic());
+  std::wistringstream ss(L"Fri Jul 5 14:58:21 2019");
+  std::ios::iostate err = std::ios::goodbit;
+  std::tm tm = {};
+  fac.get(ss, Facet::iter_type(), ss, err, &tm, 'c');
+  VERIFY( err == std::ios::eofbit );
+  VERIFY( tm.tm_year == 119 );
+  VERIFY( tm.tm_mon == 6 );
+  VERIFY( tm.tm_mday == 5 );
+  VERIFY( tm.tm_wday == 5 );
+  VERIFY( tm.tm_hour == 14 );
+  VERIFY( tm.tm_min == 58 );
+  VERIFY( tm.tm_sec == 21 );
+  ss.clear();
+  ss.seekg(0);
+  ss.str(ss.str() + L" non-whitespace after the datetime");
+  err = std::ios::goodbit;
+  tm = std::tm();
+  fac.get(ss, Facet::iter_type(), ss, err, &tm, 'c', 'E');
+  VERIFY( err == std::ios::goodbit );
+  VERIFY( tm.tm_year == 119 );
+  VERIFY( tm.tm_mon == 6 );
+  VERIFY( tm.tm_mday == 5 );
+  VERIFY( tm.tm_wday == 5 );
+  VERIFY( tm.tm_hour == 14 );
+  VERIFY( tm.tm_min == 58 );
+  VERIFY( tm.tm_sec == 21 );
+}