RFA: test C++ casts

[Jim Blandy <jimb at redhat dot com>]

2002-08-21  Jim Blandy  <jimb@redhat.com>

	* gdb.c++/casts.cc, gdb.c++/casts.exp: New test.

Index: gdb/testsuite/gdb.c++/casts.cc
===================================================================
RCS file: gdb/testsuite/gdb.c++/casts.cc
diff -N gdb/testsuite/gdb.c++/casts.cc
*** gdb/testsuite/gdb.c++/casts.cc	1 Jan 1970 00:00:00 -0000
--- gdb/testsuite/gdb.c++/casts.cc	21 Aug 2002 22:01:21 -0000
***************
*** 0 ****
--- 1,20 ----
+ struct A
+ {
+   int a;
+   A (int aa): a (aa) {}
+ };
+ 
+ struct B: public A
+ {
+   int b;
+   B (int aa, int bb): A (aa), b(bb) {}
+ };
+ 
+ int
+ main (int argc, char **argv)
+ {
+   A *a = new B(42, 1729);
+   B *b = (B *) a;
+ 
+   return 0;  /* breakpoint spot: casts.exp: 1 */
+ }
Index: gdb/testsuite/gdb.c++/casts.exp
===================================================================
RCS file: gdb/testsuite/gdb.c++/casts.exp
diff -N gdb/testsuite/gdb.c++/casts.exp
*** gdb/testsuite/gdb.c++/casts.exp	1 Jan 1970 00:00:00 -0000
--- gdb/testsuite/gdb.c++/casts.exp	21 Aug 2002 22:01:21 -0000
***************
*** 0 ****
--- 1,80 ----
+ # Copyright 2002 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.  
+ 
+ # Please email any bugs, comments, and/or additions to this file to:
+ # bug-gdb@prep.ai.mit.edu
+ 
+ # 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}
+ 
+ gdb_test "break [gdb_get_line_number "casts.exp: 1"]" \
+     "Breakpoint.*at.* file .*" \
+     ""
+ 
+ gdb_test "run" "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"