[Bug debug/8354] Incorrect DWARF-2/3 emitted for const + array

["gary at intrepid dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #12 from gary at intrepid dot com  2007-01-01 22:47 -------
Jim Wilson posted thi follow up to the GDB list:
http://sourceware.org/ml/gdb/2007-01/msg00007.html

 From: Jim Wilson <wilson at specifix dot com> 
 Date: Mon, 01 Jan 2007 14:15:47 -0800 
 Subject: RE: how to support C type qualifiers applied to arrays? 

On Thu, 2006-12-14 at 12:22 -0800, Gary Funck wrote:
> The main difficulty is that GCC doesn't create new qualified
> types for declarations.  Rather, it sets TREE_READONLY()
> and TREE_THIS_VOLATILE() in the DECL node for declarations
> such as:
>    volatile int A[10];

If you look at the types created by the C front end, they are OK.
c_build_qualified_type knows how to handle an array correctly.

The problem arises in the DWARF2 output code.  gen_type_die calls
type_main_variant for all types other than vector types, which strips
off the const and volatile type modifiers.  Then it clumsily tries to
put them back later in gen_variable_die, except that for array types, it
puts them back in the wrong place.

This seems to answer the question I asked long ago.  Why are we trying
to put back qualifiers from the decl?  Because gen_type_die stripped
them off.  This seems wrong.

If we fix gen_type_die to stop calling type_main_variant, and if we fix
gen_variable_die to stop adding back the type qualifiers, then I get the
right result.  So I think I was on the right track before, we just need
another little change to gen_type_die in addition to what I already
described.

I haven't investigated this in detail yet.  There may be other parts of
the code that expect to see a type main variant here, so we might need
other cascading fixes.  This still seems fixable to me though.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354