How do I assert that two pointers are equal with GLib's testing framework?

Question

I'm writing a unit test with GLib's testing framework where I want to check if two pointers point to the same place in memory. I do NOT want to compare the actual memory which they point to, so g_assert_cmpmem () would not be a solution.

My initial thinking was that pointers are integers, so I would just use g_assert_cmpint (). However, this generates errors as you cannot make integers from pointers without a cast:

In file included from /usr/include/glib-2.0/glib.h:89,
                 from ../src/pmos-tweaks/ms-tweaks-parser.h:11,
                 from ../src/pmos-tweaks/ms-tweaks-parser.c:11,
                 from ../tests/test-tweaks-parser.c:9:
../tests/test-tweaks-parser.c: In function ‘test_copy_setting’:
/usr/include/glib-2.0/glib/gtestutils.h:79:61: error: initialization of ‘guint64’ {aka ‘long unsigned int’} from ‘MsTweaksSetting *’ makes integer from pointer without a cast [-Wint-conversion]
   79 |                                              guint64 __n1 = (n1), __n2 = (n2); \
      |                                                             ^
../tests/test-tweaks-parser.c:53:3: note: in expansion of macro ‘g_assert_cmpuint’
   53 |   g_assert_cmpuint (setting, ==, setting_copied);
      |   ^~~~~~~~~~~~~~~~
/usr/include/glib-2.0/glib/gtestutils.h:79:74: error: initialization of ‘guint64’ {aka ‘long unsigned int’} from ‘MsTweaksSetting *’ makes integer from pointer without a cast [-Wint-conversion]
   79 |                                              guint64 __n1 = (n1), __n2 = (n2); \
      |                                                                          ^
../tests/test-tweaks-parser.c:53:3: note: in expansion of macro ‘g_assert_cmpuint’
   53 |   g_assert_cmpuint (setting, ==, setting_copied);
      |   ^~~~~~~~~~~~~~~~

Is the right solution here to just do a cast, or is there a better option?

Instead of just closing the question, maybe you could leave a comment explaining what's wrong with it? — Newbyte
– Newbyte, Commented Jul 15 at 15:51

Philip Withnall · Accepted Answer · 2025-07-14 08:29:21Z

3

There is no pointer equality assertion in GLib, so you should use g_assert_true():

g_assert_true (setting == setting_copied)

Note that you should not use g_assert(), as it will be compiled out if GLib is configured with G_DISABLE_ASSERT, and some distributions configure it this way.

answered Jul 14 at 8:29

Philip Withnall

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Leo Lindgren · Accepted Answer · 2025-07-13 13:28:48Z

1

The documentation for g_assert_cmpmem says it is equivalent to g_assert_true (l1 == l2 && memcmp (m1, m2, l1) == 0)

So you might want to use just g_assert_true(l1 == l2)

answered Jul 13 at 13:28

Leo Lindgren

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3 Comments

Rohit Gupta Jul 13 at 13:55

Please link the documentation

Eric Postpischil Jul 13 at 19:04

Thel1 and l2 arguments to g_assert_cmpmem are lengths. Asserting they are equal will not accomplish what OP asks for, asserting two pointers are equal. Did you intend to apply the comparison to pointers, not lengths?

Jonathan Leffler Jul 14 at 2:12

Maybe g_assert_true(m1 == m2)?

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