[glib: 3/4] Add tests for hash collisions in simple cases

[Marco Trevisan <marcotrevi src gnome org>]

commit e02db8ea22d545749ecaf3be9d342cc565bc143a
Author: 星外之神 <wszqkzqk qq com>
Date:   Mon Oct 10 23:58:27 2022 +0800

    Add tests for hash collisions in simple cases

 glib/tests/hash.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
---
diff --git a/glib/tests/hash.c b/glib/tests/hash.c
index 32d3579796..604dcc0492 100644
--- a/glib/tests/hash.c
+++ b/glib/tests/hash.c
@@ -459,6 +459,19 @@ int64_hash_test (void)
   g_hash_table_destroy (h);
 }
 
+static void
+int64_hash_collision_test (void)
+{
+  gint64 m;
+  gint64 n;
+
+  g_test_summary ("Check int64 Hash collisions caused by ignoring high word");
+
+  m = 722;
+  n = ((gint64) 2003 << 32) + 722;
+  g_assert_cmpuint (g_int64_hash (&m), !=, g_int64_hash (&n));
+}
+
 static void
 double_hash_test (void)
 {
@@ -488,6 +501,27 @@ double_hash_test (void)
   g_hash_table_destroy (h);
 }
 
+static void
+double_hash_collision_test (void)
+{
+  gdouble m;
+  gdouble n;
+
+  g_test_summary ("Check double Hash collisions caused by int conversion " \
+                  "and by numbers larger than 2^64-1 (G_MAXUINT64)");
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/2771";);
+
+  /* Equal when directly converted to integers */
+  m = 0.1;
+  n = 0.2;
+  g_assert_cmpuint (g_double_hash (&m), !=, g_double_hash (&n));
+
+  /* Numbers larger than 2^64-1 (G_MAXUINT64) */
+  m = 1e100;
+  n = 1e200;
+  g_assert_cmpuint (g_double_hash (&m), !=, g_double_hash (&n));
+}
+
 static void
 string_free (gpointer data)
 {
@@ -1715,7 +1749,9 @@ main (int argc, char *argv[])
   g_test_add_func ("/hash/direct2", direct_hash_test2);
   g_test_add_func ("/hash/int", int_hash_test);
   g_test_add_func ("/hash/int64", int64_hash_test);
+  g_test_add_func ("/hash/int64/collisions", int64_hash_collision_test);
   g_test_add_func ("/hash/double", double_hash_test);
+  g_test_add_func ("/hash/double/collisions", double_hash_collision_test);
   g_test_add_func ("/hash/string", string_hash_test);
   g_test_add_func ("/hash/set", set_hash_test);
   g_test_add_func ("/hash/set-ref", set_ref_hash_test);