[pancake@dazo t]$ gdb --args valac plugin.vala --pkg r_cmd --vapidir=.. --pkg r_lib  -C
GNU gdb (GDB) 7.1
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/valac...done.
(gdb) r
Starting program: /usr/bin/valac plugin.vala --pkg r_cmd --vapidir=.. --pkg r_lib -C
[Thread debugging using libthread_db enabled]
plugin.vala:15.16-15.25: error: ref and out method arguments can only be used with fields, parameters, local variables, and array element access
        RLibType.CMD, ref plugin
                      ^^^^^^^^^^

Program received signal SIGSEGV, Segmentation fault.
0xb7ea0b3c in vala_data_type_compatible (self=0x0, target_type=0x8657368)
    at valadatatype.c:1133
1133            return VALA_DATA_TYPE_GET_CLASS (self)->compatible (self, target_type);
(gdb) bt
#0  0xb7ea0b3c in vala_data_type_compatible (self=0x0, target_type=0x8657368)
    at valadatatype.c:1133
#1  0xb7e9d5e0 in vala_constant_real_check (base=0x852c830, analyzer=0x8360cd8)
    at valaconstant.c:1611
#2  0xb7e8d9a8 in vala_code_node_check (self=0x852c830, analyzer=0x8360cd8)
    at valacodenode.c:361
#3  0xb7f4dae1 in vala_source_file_check (self=0x8075530, analyzer=0x8360cd8)
    at valasourcefile.c:701
#4  0xb7f47a5c in vala_semantic_analyzer_real_visit_source_file (base=0x8360cd8, 
    file=0x8075530) at valasemanticanalyzer.c:1816
#5  0xb7e90928 in vala_code_visitor_visit_source_file (self=0x8360cd8, 
    source_file=0x8075530) at valacodevisitor.c:1317
#6  0xb7f4d65c in vala_source_file_accept (self=0x8075530, visitor=0x8360cd8)
    at valasourcefile.c:347
#7  0xb7e8c607 in vala_code_context_accept (self=0x8071008, visitor=0x8360cd8)
    at valacodecontext.c:495
#8  0xb7f472e9 in vala_semantic_analyzer_analyze (self=0x8360cd8, context=0x8071008)
    at valasemanticanalyzer.c:1804
#9  0x0804d2b3 in vala_compiler_run (argc=8, argv=0xbffff924) at valacompiler.c:761
#10 vala_compiler_main (argc=8, argv=0xbffff924) at valacompiler.c:1187
#11 main (argc=8, argv=0xbffff924) at valacompiler.c:1195

(gdb) up
#1  0xb7e9d5e0 in vala_constant_real_check (base=0x852c830, analyzer=0x8360cd8)
    at valaconstant.c:1611
1611                            if (!vala_data_type_compatible (vala_expression_get_value_type (vala_constant_get_initializer (self)), vala_constant_get_type_reference (self))) {
(gdb) print self
$1 = (ValaConstant *) 0x852c830
(gdb) print vala_constant_get_initializer(self)
$2 = (ValaExpression *) 0x85ec900
(gdb) print vala_expression_get_value_type(vala_constant_get_initializer(self))
$3 = (ValaDataType *) 0x0
