[PATCH] Fix tests that fail with _GLIBCXX_USE_CXX11_ABI=0

[Jonathan Wakely]

The pmr::string typedef isn't available for the old COW string, so some
tests that use it were failing.

        * testsuite/20_util/variant/run.cc: Use a new Hashable type to test
        hashing, because pmr::string depends on _GLIBCXX_USE_CXX11_ABI==1.
        * testsuite/21_strings/basic_string/hash/hash.cc
        [!_GLIBCXX_USE_CXX11_ABI]: Don't test pmr strings.
        * testsuite/21_strings/basic_string/hash/hash_char8_t.cc
        [!_GLIBCXX_USE_CXX11_ABI]: Likewise.

Tested x86_64-linux, committed to trunk.

I'd like to backport this to gcc-9-branch too, so all the tests pass
for the old string ABI.



commit 3161225fb11a655a3921a7a2a9f5b7cc53c7fa9e
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri Apr 26 15:59:53 2019 +0100

    Fix tests that fail with _GLIBCXX_USE_CXX11_ABI=0
    
    The pmr::string typedef isn't available for the old COW string, so some
    tests that use it were failing.
    
            * testsuite/20_util/variant/run.cc: Use a new Hashable type to test
            hashing, because pmr::string depends on _GLIBCXX_USE_CXX11_ABI==1.
            * testsuite/21_strings/basic_string/hash/hash.cc
            [!_GLIBCXX_USE_CXX11_ABI]: Don't test pmr strings.
            * testsuite/21_strings/basic_string/hash/hash_char8_t.cc
            [!_GLIBCXX_USE_CXX11_ABI]: Likewise.

diff --git a/libstdc++-v3/testsuite/20_util/variant/run.cc 
b/libstdc++-v3/testsuite/20_util/variant/run.cc
index f7353ad96b6..0416fbac12a 100644
--- a/libstdc++-v3/testsuite/20_util/variant/run.cc
+++ b/libstdc++-v3/testsuite/20_util/variant/run.cc
@@ -22,7 +22,6 @@
 #include <string>
 #include <vector>
 #include <unordered_set>
-#include <memory_resource>
 #include <ext/throw_allocator.h>
 #include <testsuite_hooks.h>
 
@@ -433,9 +432,30 @@ void test_visit()
   }
 }
 
+struct Hashable
+{
+  Hashable(const char* s) : s(s) { }
+  // Non-trivial special member functions:
+  Hashable(const Hashable&) { }
+  Hashable(Hashable&&) noexcept { }
+  ~Hashable() { }
+
+  string s;
+
+  bool operator==(const Hashable& rhs) const noexcept
+  { return s == rhs.s; }
+};
+
+namespace std {
+  template<> struct hash<Hashable> {
+    size_t operator()(const Hashable& h) const noexcept
+    { return hash<std::string>()(h.s); }
+  };
+}
+
 void test_hash()
 {
-  unordered_set<variant<int, pmr::string>> s;
+  unordered_set<variant<int, Hashable>> s;
   VERIFY(s.emplace(3).second);
   VERIFY(s.emplace("asdf").second);
   VERIFY(s.emplace().second);
@@ -447,12 +467,12 @@ void test_hash()
   {
     struct A
     {
-      operator pmr::string()
+      operator Hashable()
       {
         throw nullptr;
       }
     };
-    variant<int, pmr::string> v;
+    variant<int, Hashable> v;
     try
       {
         v.emplace<1>(A{});
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash.cc 
b/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash.cc
index 9bdf9bd41ab..413c22bd16b 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash.cc
@@ -39,19 +39,29 @@ void
 test01()
 {
   VERIFY( test(std::string("a narrow string")) );
-  VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
   VERIFY( test(std::u16string(u"a utf-16 string")) );
-  VERIFY( test(std::pmr::u16string(u"a utf-16 string, but with PMR!")) );
   VERIFY( test(std::u32string(U"a utf-32 string")) );
-  VERIFY( test(std::pmr::u32string(U"a utf-32 string, but with PMR!")) );
 #if _GLIBCXX_USE_WCHAR_T
   VERIFY( test(std::wstring(L"a wide string")) );
+#endif
+}
+
+void
+test02()
+{
+#if _GLIBCXX_USE_CXX11_ABI
+  VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
+  VERIFY( test(std::pmr::u16string(u"a utf-16 string, but with PMR!")) );
+  VERIFY( test(std::pmr::u32string(U"a utf-32 string, but with PMR!")) );
+#if _GLIBCXX_USE_WCHAR_T
   VERIFY( test(std::pmr::wstring(L"a wide string, but with PMR!")) );
 #endif
+#endif
 }
 
 int
 main()
 {
   test01();
+  test02();
 }
diff --git 
a/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash_char8_t.cc 
b/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash_char8_t.cc
index 0e4cfae4b76..ad02fcc98ec 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash_char8_t.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/hash/hash_char8_t.cc
@@ -39,9 +39,11 @@ void
 test01()
 {
   VERIFY( test(std::string("a narrow string")) );
-  VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
   VERIFY( test(std::u8string(u8"a utf-8 string")) );
+#if _GLIBCXX_USE_CXX11_ABI
+  VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
   VERIFY( test(std::pmr::u8string(u8"a utf-8 string, but with PMR!")) );
+#endif
 }
 
 void