[Bug gdb/28104] Incorrect extraction of boolean fields in target description "struct" data type

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

https://sourceware.org/bugzilla/show_bug.cgi?id=28104

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The gdb-11-branch branch has been updated by Shahab Vahedi
<shahab@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e4c1aea498ff84bcb3086509d125ac8249f35db2

commit e4c1aea498ff84bcb3086509d125ac8249f35db2
Author: Shahab Vahedi <shahab@synopsys.com>
Date:   Mon Jul 19 16:13:47 2021 +0200

    gdb: Make the builtin "boolean" type an unsigned type

    When printing the fields of a register that is of a custom struct type,
    the "unpack_bits_as_long ()" function is used:

        do_val_print (...)
          cp_print_value_fields (...)
            value_field_bitfield (...)
              unpack_value_bitfield (...)
                unpack_bits_as_long (...)

    This function may sign-extend the extracted field while returning it:

        val >>= lsbcount;

        if (...)
          {
            valmask = (((ULONGEST) 1) << bitsize) - 1;
            val &= valmask;
            if (!field_type->is_unsigned ())
              if (val & (valmask ^ (valmask >> 1)))
                  val |= ~valmask;
          }

        return val;

    lsbcount:   Number of lower bits to get rid of.
    bitsize:    The bit length of the field to be extracted.
    val:        The register value.
    field_type: The type of field that is being handled.

    While the logic here is correct, there is a problem when it is
    handling "field_type"s of "boolean".  Those types are NOT marked
    as "unsigned" and therefore they end up being sign extended.
    Although this is not a problem for "false" (0), it definitely
    causes trouble for "true".

    This patch constructs the builtin boolean type as such that it is
    marked as an "unsigned" entity.

    The issue tackled here was first encountered for arc-elf32 target
    running on an x86_64 machine.  The unit-test introduced in this change
    has passed for all the targets (--enable-targets=all) running on the
    same x86_64 host.

    gdb/ChangeLog:

            PR gdb/28104
            * gdbtypes.c (gdbtypes_post_init): Use
            "arch_boolean_type (..., unsigned=1, ...) to construct
            "boolean".
            cp-valprint.c (test_print_flags): New.
            (_initialize_cp_valprint): Run the "test_print_flags" unit-test.

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