binutils-gdb/gdb/testsuite/gdb.cp/watch-cp.exp
Andreas Arnez e95a97d41a Fix watching structs in C++
Some of the watchpoint logic depends on the fact that the head of the
value chain represents the user-specified value to watch.  Thus no
additional values should be added to the value chain after that.  However,
if a watchpoint is defined for a C++ structure/class object, then run-time
type information (RTTI) may be present.  Thus, while constructing the
value chain for the watchpoint, the dynamic type is fetched by
gnuv3_rrti_type, which invokes value_addr, which then adds a new value to
the head of the value chain.  This new value represents the pointer to the
structure instead of the structure itself.

With such a "polluted" value chain the watchpoint logic does not recognize
when the user intended to watch a struct, and can_use_hardware_watchpoint
returns zero.  Instead of a hardware watchpoint, a software watchpoint
will then be set for no apparent reason.

This is fixed by adding an early exit to gnuv3_rtti_type when the input
value is not a dynamic class object.

gdb/testsuite/ChangeLog:

	* gdb.cp/watch-cp.cc: New test.
	* gdb.cp/watch-cp.exp: New file.

gdb/ChangeLog:

	* gnu-v3-abi.c (gnuv3_rtti_type): Add early exit if the given
	value is not a dynamic class object.
2018-03-07 14:29:19 +01:00

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# Copyright 2018 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 3 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, see <http://www.gnu.org/licenses/>.
if { [skip_cplus_tests] || [skip_hw_watchpoint_tests]} { continue }
standard_testfile .cc
if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
return -1
}
if ![runto_main] then {
perror "couldn't run to main"
continue
}
gdb_test "watch watchme\[3\]" "atchpoint .*: watchme.*" "set watchpoint"
# Verify that a hardware watchpoint is used.
gdb_test "info watchpoints" " hw watchpoint .* watchme.*"
# Now see whether it actually works.
gdb_test "continue" "Hardware watchpoint .*New value = \\{n = 3\\}.*"