casts.exp   [plain text]

# Copyright 2002, 2003, 2004 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  

# This file is part of the gdb testsuite

# Test casting, especially between class types or pointer-to-class
# types.

# This file is part of the gdb testsuite

if $tracelevel then {
        strace $tracelevel
        }

#
# test running programs
#

set prms_id 0
set bug_id 0

if { [skip_cplus_tests] } { continue }

set testfile "casts"
set srcfile ${testfile}.cc
set binfile ${objdir}/${subdir}/${testfile}

if [get_compiler_info ${binfile} "c++"] {
    return -1;
}

if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug c++}] != "" } {
     gdb_suppress_entire_file "Testcase compile failed, so all tests in this file will automatically fail."
}


gdb_exit
gdb_start
gdb_reinitialize_dir $srcdir/$subdir
gdb_load ${binfile}

if ![runto_main] then {
    perror "couldn't run to breakpoint"
    continue
}

gdb_test "break [gdb_get_line_number "casts.exp: 1"]" \
    "Breakpoint.*at.* file .*" \
    ""

gdb_test "continue" "Breakpoint .* at .*casts.cc.*" ""

# Casting a pointer to a base class to a pointer to a derived class
# should yield the entire derived class.  Until August 2002, GDB got
# the enclosing type on `(B *) a' wrong: while the value's static type
# was `B *', as it should be, the enclosing type (which is supposed to
# be the dynamic type) was `A *'.  It's senseless to have a static
# type derived from the dynamic type; it should be the other way
# 'round.  Dereferencing this oddly typed pointer yielded a value in
# which only the base class's members were initialized, since GDB uses
# the enclosing type to decide how many bytes to read.  Members from
# the derived class were garbage, from GDB's address space.
gdb_test "print * (B *) a" ".* = {<A> = {a = 42}, b = 1729}" \
    "cast base class pointer to derived class pointer"

# Check also that we get the same results from letting the compiler do
# the dereference.
gdb_test "print * b" ".* = {<A> = {a = 42}, b = 1729}" \
    "let compiler cast base class pointer to derived class pointer"