Copy string_view tests from libstdc++

This patch copies the string_view tests from the gcc repository (commit
02a4441f002c).

  ${gcc}/libstdc++-v3/testsuite/21_strings/basic_string_view ->
    ${binutils-gdb}/gdb/unittests/basic_string_view

The local modifications are done in the following patch, so that it's
easier to review them.

gdb/ChangeLog:

	* unittests/basic_string_view/capacity/1.cc: New file.
	* unittests/basic_string_view/capacity/empty_neg.cc: New file.
	* unittests/basic_string_view/cons/char/1.cc: New file.
	* unittests/basic_string_view/cons/char/2.cc: New file.
	* unittests/basic_string_view/cons/char/3.cc: New file.
	* unittests/basic_string_view/cons/wchar_t/1.cc: New file.
	* unittests/basic_string_view/cons/wchar_t/2.cc: New file.
	* unittests/basic_string_view/cons/wchar_t/3.cc: New file.
	* unittests/basic_string_view/element_access/char/1.cc: New file.
	* unittests/basic_string_view/element_access/char/2.cc: New file.
	* unittests/basic_string_view/element_access/char/empty.cc: New file.
	* unittests/basic_string_view/element_access/char/front_back.cc: New file.
	* unittests/basic_string_view/element_access/wchar_t/1.cc: New file.
	* unittests/basic_string_view/element_access/wchar_t/2.cc: New file.
	* unittests/basic_string_view/element_access/wchar_t/empty.cc: New file.
	* unittests/basic_string_view/element_access/wchar_t/front_back.cc: New file.
	* unittests/basic_string_view/include.cc: New file.
	* unittests/basic_string_view/inserters/char/1.cc: New file.
	* unittests/basic_string_view/inserters/char/2.cc: New file.
	* unittests/basic_string_view/inserters/char/3.cc: New file.
	* unittests/basic_string_view/inserters/pod/10081-out.cc: New file.
	* unittests/basic_string_view/inserters/wchar_t/1.cc: New file.
	* unittests/basic_string_view/inserters/wchar_t/2.cc: New file.
	* unittests/basic_string_view/inserters/wchar_t/3.cc: New file.
	* unittests/basic_string_view/literals/types.cc: New file.
	* unittests/basic_string_view/literals/values.cc: New file.
	* unittests/basic_string_view/modifiers/remove_prefix/char/1.cc: New file.
	* unittests/basic_string_view/modifiers/remove_prefix/wchar_t/1.cc: New file.
	* unittests/basic_string_view/modifiers/remove_suffix/char/1.cc: New file.
	* unittests/basic_string_view/modifiers/remove_suffix/wchar_t/1.cc: New file.
	* unittests/basic_string_view/modifiers/swap/char/1.cc: New file.
	* unittests/basic_string_view/modifiers/swap/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/compare/char/1.cc: New file.
	* unittests/basic_string_view/operations/compare/char/13650.cc: New file.
	* unittests/basic_string_view/operations/compare/char/2.cc: New file.
	* unittests/basic_string_view/operations/compare/char/70483.cc: New file.
	* unittests/basic_string_view/operations/compare/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/compare/wchar_t/13650.cc: New file.
	* unittests/basic_string_view/operations/compare/wchar_t/2.cc: New file.
	* unittests/basic_string_view/operations/copy/char/1.cc: New file.
	* unittests/basic_string_view/operations/copy/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/data/char/1.cc: New file.
	* unittests/basic_string_view/operations/data/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/find/char/1.cc: New file.
	* unittests/basic_string_view/operations/find/char/2.cc: New file.
	* unittests/basic_string_view/operations/find/char/3.cc: New file.
	* unittests/basic_string_view/operations/find/char/4.cc: New file.
	* unittests/basic_string_view/operations/find/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/find/wchar_t/2.cc: New file.
	* unittests/basic_string_view/operations/find/wchar_t/3.cc: New file.
	* unittests/basic_string_view/operations/find/wchar_t/4.cc: New file.
	* unittests/basic_string_view/operations/rfind/char/1.cc: New file.
	* unittests/basic_string_view/operations/rfind/char/2.cc: New file.
	* unittests/basic_string_view/operations/rfind/char/3.cc: New file.
	* unittests/basic_string_view/operations/rfind/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operations/rfind/wchar_t/2.cc: New file.
	* unittests/basic_string_view/operations/rfind/wchar_t/3.cc: New file.
	* unittests/basic_string_view/operations/string_conversion/1.cc: New file.
	* unittests/basic_string_view/operations/substr/char/1.cc: New file.
	* unittests/basic_string_view/operations/substr/wchar_t/1.cc: New file.
	* unittests/basic_string_view/operators/char/2.cc: New file.
	* unittests/basic_string_view/operators/wchar_t/2.cc: New file.
	* unittests/basic_string_view/range_access/char/1.cc: New file.
	* unittests/basic_string_view/range_access/wchar_t/1.cc: New file.
	* unittests/basic_string_view/requirements/explicit_instantiation/1.cc: New file.
	* unittests/basic_string_view/requirements/explicit_instantiation/char/1.cc: New file.
	* unittests/basic_string_view/requirements/explicit_instantiation/char16_t/1.cc: New file.
	* unittests/basic_string_view/requirements/explicit_instantiation/char32_t/1.cc: New file.
	* unittests/basic_string_view/requirements/explicit_instantiation/wchar_t/1.cc: New file.
	* unittests/basic_string_view/requirements/typedefs.cc: New file.
	* unittests/basic_string_view/typedefs.cc: New file.
	* unittests/basic_string_view/types/1.cc: New file.

2 files changed, 190 insertions, 0 deletions

diff --git a/gdb/unittests/basic_string_view/capacity/1.cc b/gdb/unittests/basic_string_view/capacity/1.cc
new file mode 100644
index 0000000..d49ecbd
--- /dev/null
+++ b/gdb/unittests/basic_string_view/capacity/1.cc
@@ -0,0 +1,162 @@
+// { dg-options "-std=gnu++17" }
+
+// Copyright (C) 2013-2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// string_view size, length
+
+#include <string_view>
+#include <cstring>
+#include <testsuite_hooks.h>
+
+template<typename T>
+  struct A { };
+
+template<typename T>
+  bool
+  operator==(const A<T>&, const A<T>&) { return true; }
+
+template<typename T>
+  bool
+  operator<(const A<T>&, const A<T>&) { return true; }
+
+struct B { };
+
+// char_traits specialization
+namespace std
+{
+  template<>
+    struct char_traits<A<B> >
+    {
+      typedef A<B> 		char_type;
+      // Unsigned as wint_t in unsigned.
+      typedef unsigned long  	int_type;
+      typedef streampos 	pos_type;
+      typedef streamoff 	off_type;
+      typedef mbstate_t 	state_type;
+      
+      static void 
+      assign(char_type& __c1, const char_type& __c2)
+      { __c1 = __c2; }
+
+      static bool 
+      eq(const char_type& __c1, const char_type& __c2)
+      { return __c1 == __c2; }
+
+      static bool 
+      lt(const char_type& __c1, const char_type& __c2)
+      { return __c1 < __c2; }
+
+      static int 
+      compare(const char_type* __s1, const char_type* __s2, size_t __n)
+      { 
+	for (size_t __i = 0; __i < __n; ++__i)
+	  if (!eq(__s1[__i], __s2[__i]))
+	    return lt(__s1[__i], __s2[__i]) ? -1 : 1;
+	return 0; 
+      }
+
+      static size_t
+      length(const char_type* __s)
+      { 
+	const char_type* __p = __s; 
+	while (__p) 
+	  ++__p; 
+	return (__p - __s); 
+      }
+
+      static const char_type* 
+      find(const char_type* __s, size_t __n, const char_type& __a)
+      { 
+	for (const char_type* __p = __s; size_t(__p - __s) < __n; ++__p)
+	  if (*__p == __a) return __p;
+	return 0;
+      }
+
+      static char_type* 
+      move(char_type* __s1, const char_type* __s2, size_t __n)
+      { return (char_type*) memmove(__s1, __s2, __n * sizeof(char_type)); }
+
+      static char_type* 
+      copy(char_type* __s1, const char_type* __s2, size_t __n)
+      { return (char_type*) memcpy(__s1, __s2, __n * sizeof(char_type)); }
+
+      static char_type* 
+      assign(char_type* __s, size_t __n, char_type __a)
+      { 
+	for (char_type* __p = __s; __p < __s + __n; ++__p) 
+	  assign(*__p, __a);
+        return __s; 
+      }
+
+      static char_type 
+      to_char_type(const int_type&)
+      { return char_type(); }
+
+      static int_type 
+      to_int_type(const char_type&) { return int_type(); }
+
+      static bool 
+      eq_int_type(const int_type& __c1, const int_type& __c2)
+      { return __c1 == __c2; }
+
+      static int_type 
+      eof() { return static_cast<int_type>(-1); }
+
+      static int_type 
+      not_eof(const int_type& __c)
+      { return eq_int_type(__c, eof()) ? int_type(0) : __c; }
+    };
+} // namespace std
+
+void
+test01()
+{
+  std::basic_string_view<A<B>> str02;
+  typedef std::basic_string_view< A<B> >::size_type size_type_o;
+  size_type_o sz03;
+  size_type_o sz04;
+
+  // non-POD types: size, length, max_size, empty()
+  bool b01 = str02.empty();  
+  VERIFY( b01 == true );
+  sz03 = str02.size();
+  sz04 = str02.length();
+  VERIFY( sz03 == sz04 );
+  str02.data();
+  sz03 = str02.size();
+  sz04 = str02.length();
+  VERIFY( sz03 == sz04 );
+
+  sz03 = str02.max_size();  
+  VERIFY( sz03 >= sz04 );
+
+  sz03 = str02.size();
+  str02 = {};
+  b01 = str02.empty(); 
+  VERIFY( b01 == true );
+  sz04 = str02.size();  
+  VERIFY( sz03 >= sz04 );
+}
+
+int
+main()
+{
+  test01();
+
+  return 0;
+}
diff --git a/gdb/unittests/basic_string_view/capacity/empty_neg.cc b/gdb/unittests/basic_string_view/capacity/empty_neg.cc
new file mode 100644
index 0000000..4ea5063
--- /dev/null
+++ b/gdb/unittests/basic_string_view/capacity/empty_neg.cc
@@ -0,0 +1,28 @@
+// Copyright (C) 2017-2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do compile { target c++17 } }
+
+#include <string_view>
+
+void
+test01()
+{
+  std::string_view s;
+  s.empty();  // { dg-warning "ignoring return value" }
+}