Adapt and integrate string_view tests

The previous patch copied the string_view tests from libstdc++.  This
patch adjusts them in a similar way that the libstdc++ optional tests
are integrated in our unit test suite.

Not all tests are used, some of them require language features not
present in c++11.  For example, we can't use a string_view constructor
where the length is not explicit in a constexpr, because
std::char_traits::length is not a constexpr itself (it is in c++17
though).  Nevertheless, a good number of tests are integrated, which
covers pretty well the string_view features.

gdb/ChangeLog:

	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	string_view-selftests.c.
	* unittests/basic_string_view/capacity/1.cc: Adapt to GDB
	testsuite.
	* unittests/basic_string_view/cons/char/1.cc: Likewise.
	* unittests/basic_string_view/cons/char/2.cc: Likewise.
	* unittests/basic_string_view/cons/char/3.cc: Likewise.
	* unittests/basic_string_view/element_access/char/1.cc:
	Likewise.
	* unittests/basic_string_view/element_access/char/empty.cc:
	Likewise.
	* unittests/basic_string_view/element_access/char/front_back.cc:
	Likewise.
	* unittests/basic_string_view/inserters/char/2.cc: Likewise.
	* unittests/basic_string_view/modifiers/remove_prefix/char/1.cc:
	Likewise.
	* unittests/basic_string_view/modifiers/remove_suffix/char/1.cc:
	Likewise.
	* unittests/basic_string_view/modifiers/swap/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/compare/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/compare/char/13650.cc:
	Likewise.
	* unittests/basic_string_view/operations/copy/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/data/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/find/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/find/char/2.cc:
	Likewise.
	* unittests/basic_string_view/operations/find/char/3.cc:
	Likewise.
	* unittests/basic_string_view/operations/find/char/4.cc:
	Likewise.
	* unittests/basic_string_view/operations/rfind/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operations/rfind/char/2.cc:
	Likewise.
	* unittests/basic_string_view/operations/rfind/char/3.cc:
	Likewise.
	* unittests/basic_string_view/operations/substr/char/1.cc:
	Likewise.
	* unittests/basic_string_view/operators/char/2.cc: Likewise.
	* unittests/string_view-selftests.c: New file.

3 files changed, 22 insertions, 11 deletions

diff --git a/gdb/unittests/basic_string_view/modifiers/remove_prefix/char/1.cc b/gdb/unittests/basic_string_view/modifiers/remove_prefix/char/1.cc
index ba08a98..f73fdc7 100644
--- a/gdb/unittests/basic_string_view/modifiers/remove_prefix/char/1.cc
+++ b/gdb/unittests/basic_string_view/modifiers/remove_prefix/char/1.cc
@@ -17,13 +17,12 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include <string_view>
-#include <testsuite_hooks.h>
+namespace modifiers_remove_prefix {
 
 void
 test01()
 {
-  using std::string_view;
+  using gdb::string_view;
 
   string_view str0{"olympus mons"};
   string_view::pointer p = str0.data();
@@ -33,6 +32,7 @@ test01()
   VERIFY( str0 == string_view{"pus mons"} );
 }
 
+#ifndef GDB_STRING_VIEW
 constexpr bool
 test02()
 {
@@ -50,12 +50,17 @@ test02()
 
   return true;
 }
+#endif
 
 int
 main()
 { 
   test01();
+#ifndef GDB_STRING_VIEW
   static_assert( test02() );
+#endif
 
   return 0;
 }
+
+} // namespace modifiers_remove_prefix
diff --git a/gdb/unittests/basic_string_view/modifiers/remove_suffix/char/1.cc b/gdb/unittests/basic_string_view/modifiers/remove_suffix/char/1.cc
index 1b71ee9..0407f37 100644
--- a/gdb/unittests/basic_string_view/modifiers/remove_suffix/char/1.cc
+++ b/gdb/unittests/basic_string_view/modifiers/remove_suffix/char/1.cc
@@ -17,13 +17,12 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include <string_view>
-#include <testsuite_hooks.h>
+namespace modifiers_remove_suffix {
 
 void
 test01()
 {
-  using std::string_view;
+  using gdb::string_view;
 
   string_view str0{"olympus mons"};
   string_view::pointer p = str0.data();
@@ -33,6 +32,7 @@ test01()
   VERIFY( str0 == string_view{"olympus mo"} );
 }
 
+#ifndef GDB_STRING_VIEW
 constexpr bool
 test02()
 {
@@ -50,12 +50,17 @@ test02()
 
   return true;
 }
+#endif
 
 int
 main()
 { 
   test01();
+#ifndef GDB_STRING_VIEW
   static_assert( test02() );
+#endif
 
   return 0;
 }
+
+} // namespace modifiers_remove_suffix
diff --git a/gdb/unittests/basic_string_view/modifiers/swap/char/1.cc b/gdb/unittests/basic_string_view/modifiers/swap/char/1.cc
index 90d2669..3bc7f01 100644
--- a/gdb/unittests/basic_string_view/modifiers/swap/char/1.cc
+++ b/gdb/unittests/basic_string_view/modifiers/swap/char/1.cc
@@ -18,18 +18,19 @@
 // { dg-options "-std=gnu++17" }
 // { dg-do compile { target c++17 } }
 
-#include <string_view>
+namespace modifiers_swap {
 
-constexpr bool
+void
 test01()
 {
-  using std::string_view;
+  using gdb::string_view;
 
   string_view s1{"last"};
   string_view s2{"first"};
 
   s1.swap(s2);
-  return s1 == "first" && s2 == "last";
+  VERIFY( s1 == "first" );
+  VERIFY( s2 == "last" );
 }
 
-static_assert( test01() );
+} // namespace modifiers_swap