[Issue 4863] New: DWARF debug symbols treat arrays as unsigned long long

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4863

           Summary: DWARF debug symbols treat arrays as unsigned long long
           Product: D
           Version: D2
          Platform: x86
        OS/Version: FreeBSD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: bugs-puremagic at jelal.kn-bremen.de


--- Comment #0 from Juergen Lock <bugs-puremagic at jelal.kn-bremen.de> 2010-09-13 15:34:38 PDT ---
(I haven't checked if this also affects D1, and it probably also affects
non-FreeBSD *ixes at least.)

I tested both gdb head (checked out after the D patches went in) and Doug
Rabson's D-aware debugger ngdb which he annouced as a 'Technology Preview'
here:

    http://lists.freebsd.org/pipermail/freebsd-current/2009-August/011071.html

..and found two things:

a) gdb still chokes on dmd -g debug symbols because the
   D DWARF extensions conflict with DWARF-4:

    http://d.puremagic.com/issues/show_bug.cgi?id=4180

   disabling the DW_TAG_type_unit case in gdb/dwarf2read.c
   at least makes it no longer complain:

    http://people.freebsd.org/~nox/tmp/d/d-gdb-dwarf2read.c.patch

b) both debuggers treat arrays as unsigned long long (like main()'s standard
string[] args) - at least ngdb prints them correctly if I do a manual cast:

    (ngdb) p *cast(char [][] *)&args

   I then looked at the debug symbols using readelf -w and found it's actually
dmd's fault not the debugger's, the array really seems to be marked as the
unsigned long long type:

    <1><a4>: Abbrev Number: 3 (DW_TAG_base_type)
         DW_AT_name        : unsigned long long
         DW_AT_byte_size   : 8
         DW_AT_encoding    : 7      (unsigned)
    ..
    <2><516>: Abbrev Number: 5 (DW_TAG_formal_parameter)
         DW_AT_name        : args
         DW_AT_type        : <a4>
         DW_AT_location    : 2 byte block: 91 8     (DW_OP_fbreg: 8)

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