hash-map-tests.c (test_map_of_strings_to_int): Show how to use string contents as hash_map keys.

	* hash-map-tests.c (test_map_of_strings_to_int): Show how to use
	string contents as hash_map keys.

From-SVN: r268121

gcc/ChangeLog

+2019-01-21  Michael Ploujnikov  <michael.ploujnikov@oracle.com>
+
+	* hash-map-tests.c (test_map_of_strings_to_int): Show how to use
+	string contents as hash_map keys.
+
 2019-01-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
 	PR c/88928

gcc/hash-map-tests.c

@@ -77,6 +77,26 @@ test_map_of_strings_to_int ()
   m.remove (eric);
   ASSERT_EQ (5, m.elements ());
   ASSERT_EQ (NULL, m.get (eric));
+
+  /* A plain char * key is hashed based on its value (address), rather
+     than the string it points to.  */
+  char *another_ant = static_cast <char *> (xcalloc (4, 1));
+  another_ant[0] = 'a';
+  another_ant[1] = 'n';
+  another_ant[2] = 't';
+  another_ant[3] = 0;
+  ASSERT_NE (ant, another_ant);
+  unsigned prev_size = m.elements ();
+  ASSERT_EQ (false, m.put (another_ant, 7));
+  ASSERT_EQ (prev_size + 1, m.elements ());
+
+  /* Need to use string_hash or nofree_string_hash key types to hash
+     based on the string contents.  */
+  hash_map <nofree_string_hash, int> string_map;
+  ASSERT_EQ (false, string_map.put (ant, 1));
+  ASSERT_EQ (1, string_map.elements ());
+  ASSERT_EQ (true, string_map.put (another_ant, 5));
+  ASSERT_EQ (1, string_map.elements ());
 }
 
 /* Run all of the selftests within this file.  */