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11aa919a07
Consider the following declarations:
type Packed_Array is array (Natural range <>) of Boolean;
pragma Pack (Packed_Array);
function Make (H, L : Natural) return Packed_Array is
begin
return (H .. L => False);
end Make;
A1 : Packed_Array := Make (1, 2);
A2 : Packed_Array renames A1;
One possible DWARF translation for A2 is:
<3><1e4>: Abbrev Number: 21 (DW_TAG_variable)
<1e5> DW_AT_name : a2
<1ea> DW_AT_type : <0x1d9>
<3><1d9>: Abbrev Number: 22 (DW_TAG_const_type)
<1da> DW_AT_type : <0x1de>
<3><1de>: Abbrev Number: 23 (DW_TAG_reference_type)
<1e0> DW_AT_type : <0x1a3>
<3><1a3>: Abbrev Number: 17 (DW_TAG_array_type)
<1a4> DW_AT_name : foo__Ta1S___XP1
<1a8> DW_AT_GNAT_descriptive_type: <0x16b>
<3><16b>: Abbrev Number: 6 (DW_TAG_typedef)
<16c> DW_AT_name : foo__Ta1S
<172> DW_AT_type : <0x176>
<3><176>: Abbrev Number: 17 (DW_TAG_array_type)
<177> DW_AT_name : foo__Ta1S
<17b> DW_AT_GNAT_descriptive_type: <0x223>
Here, foo__Ta1S___XP1 is the type used for the code generation while
foo__Ta1S is the source-level type. Both form a valid GNAT encoding for
a packed array type.
Trying to print A2 (1) can make GDB crash. This is because A2 is defined
as a reference to a GNAT encoding for a packed array. When decoding
constrained packed arrays, the ada_coerce_ref subprogram follows
references and returns a fixed type from the target type, peeling
the GNAT encoding for packed arrays. The remaining code assumes that
the resulting type is still such an encoding while we only have
a standard GDB array type, hence the crash:
arr = ada_coerce_ref (arr);
[...]
type = decode_constrained_packed_array_type (value_type (arr));
decode_constrained_packed_array_type assumes that its argument is
such an encoding. From its front comment:
/* The array type encoded by TYPE, where
ada_is_constrained_packed_array_type (TYPE). */
This patch simply replaces the call to ada_coerce_ref with a call
to coerce_ref in order to avoid prematurely transforming
the packed array type as a side-effect. This way, the remaining code
will always work with a GNAT encoding.
gdb/ChangeLog:
* ada-lang.c (decode_constrained_packed_array): Perform a
minimal coercion for reference with coerce_ref instead of
ada_coerce_ref.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.