The following line in the gobject testsuite (gobject/tests/param.c) is IMHO buggy:

  CHECK_INT_CONVERSION(G_TYPE_CHAR, char, -124)

You cannot assume that this works without specifying that char needs to be signed.  On architectures where C's standard char is unsigned (armel, s390, s390x, powerpc, avr32) this then fails:

TEST: param... (pid=17482)
**
ERROR:/build/buildd-glib2.0_2.30.2-4-s390x-0J7ZlY/glib2.0-2.30.2/./gobject/tests/param.c:148:test_value_transform:
assertion failed (g_value_get_char (&dest) == -124): (132 == -124)
  /value/transform:                                                    FAIL
GTester: last random seed: R02S186980d972380fe09bc2895cde5249ba
/bin/bash: line 1: 17430 Terminated              MALLOC_CHECK_=2
MALLOC_PERTURB_=$((${RANDOM:-256} % 256)) ../../glib/gtester --verbose boxed
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