[Bug gdb/21356] value.c:828: internal-error: int value_contents_bits_eq(const value*, int, const value*, int, int): Assertion `offset1 + length <= TYPE_LENGTH (val1->enclosing_type) * TARGET_CHAR_BIT' failed

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=21356

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2f33032a93f24ccc0c0d2f23e2a3ec0442f638d4

commit 2f33032a93f24ccc0c0d2f23e2a3ec0442f638d4
Author: Keith Seitz <keiths@redhat.com>
Date:   Thu Jun 11 14:34:44 2020 +0200

    Compute proper length for dynamic types of TYPE_CODE_TYPEDEF

    This patch fixes gdb/21356 in which we hit an assertion in
    value_contents_bits_eq:

    (gdb) p container_object2
    (gdb) p container_object2
    $1 = {_container_member2 = 15, _vla_struct_object2 = {_some_member = 0,
        _vla_field = {
    ../../src/gdb/value.c:829: internal-error: \
      int value_contents_bits_eq(const value*, int, const value*, int, int): \
      Assertion `offset1 + length \
                 <= TYPE_LENGTH (val1->enclosing_type) * TARGET_CHAR_BIT'
failed.

    This is happening because TYPE_LENGTH (val1->enclosing_type) is erroneously
    based on enclosing_type, which is a typedef, instead of the actual
underlying
    type.

    This can be traced back to resolve_dynamic_struct, where the size of the
    type is computed:
    ...
            TYPE_FIELD_TYPE (resolved_type, i)
              = resolve_dynamic_type_internal (TYPE_FIELD_TYPE (resolved_type,
i),
                                               &pinfo, 0);
            gdb_assert (TYPE_FIELD_LOC_KIND (resolved_type, i)
                        == FIELD_LOC_KIND_BITPOS);

            new_bit_length = TYPE_FIELD_BITPOS (resolved_type, i);
            if (TYPE_FIELD_BITSIZE (resolved_type, i) != 0)
              new_bit_length += TYPE_FIELD_BITSIZE (resolved_type, i);
            else
              new_bit_length += (TYPE_LENGTH (TYPE_FIELD_TYPE (resolved_type,
i))
                                 * TARGET_CHAR_BIT);
    ...

    In this function, resolved_type is TYPE_CODE_TYPEDEF which is not what we
    want to use to calculate the size of the actual field.

    This patch fixes this and the similar problem in resolve_dynamic_union.

    gdb/ChangeLog:
    2020-06-11  Keith Seitz  <keiths@redhat.com>

            PR gdb/21356
            * gdbtypes.c (resolve_dynamic_union, resolve_dynamic_struct):
            Resolve typedefs for type length calculations.

    gdb/testsuite/ChangeLog:
    2020-06-11  Keith Seitz  <keiths@redhat.com>

            PR gdb/21356
            * gdb.base/vla-datatypes.c (vla_factory): Add typedef for struct
            vla_struct.
            Add new struct vla_typedef and union vla_typedef_union and
            corresponding instantiation objects.
            Initialize new objects.
            * gdb.base/vla-datatypes.exp: Add tests for
vla_typedef_struct_object
            and vla_typedef_union_object.
            Fixup type for vla_struct_object.

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