GDB currently crashes with infinite recursion, if you set a breakpoint
on a function inside a namespace that includes a template on its fully
qualified name, and, the template's name is also used as typedef in
the global scope that expands to a name that includes the template
name in its qualified name. For example, from the testcase added by
this commit:
namespace NS1 { namespace NS2 {
template<typename T> struct Templ1
{
T x;
Templ1 (object_p) {}
}} // namespace NS1::NS2
using Templ1 = NS1::NS2::Templ1<unsigned>;
Setting a breakpoint like so:
(gdb) break NS1::NS2::Templ1<int>::Templ1(NS1::NS2::object*)
Results in infinite recursion, with this cycle (started by
cp_canonicalize_string_full) repeating until the stack is exhausted:
...
#1709 0x000000000055533c in inspect_type (info=0x38ff720, ret_comp=0xd83be10, finder=0x0, data=0x0) at /home/pedro/gdb/mygit/src/gdb/cp-support.c:267
#1710 0x0000000000555a6f in replace_typedefs (info=0x38ff720, ret_comp=0xd83be10, finder=0x0, data=0x0) at /home/pedro/gdb/mygit/src/gdb/cp-support.c:475
#1711 0x0000000000555a36 in replace_typedefs (info=0x38ff720, ret_comp=0xd83be70, finder=0x0, data=0x0) at /home/pedro/gdb/mygit/src/gdb/cp-support.c:470
#1712 0x0000000000555800 in replace_typedefs_qualified_name (info=0x38ff720, ret_comp=0xd839470, finder=0x0, data=0x0) at /home/pedro/gdb/mygit/src/gdb/cp-support.c:389
#1713 0x0000000000555a8c in replace_typedefs (info=0x38ff720, ret_comp=0xd839470, finder=0x0, data=0x0) at /home/pedro/gdb/mygit/src/gdb/cp-support.c:479
...
The demangle component tree for that symbol name looks like this:
d_dump tree for NS1::NS2::Templ1<int>::Templ1(NS1::NS2::object*):
typed name
qualified name
name 'NS1'
qualified name
name 'NS2'
qualified name
template <<<<<<<<<<
name 'Templ1'
template argument list
builtin type int
name 'Templ1'
function type
argument list
pointer
qualified name
name 'NS1'
qualified name
name 'NS2'
name 'object'
The recursion starts at replace_typedefs_qualified_name, which doesn't
handle the "template" node, and thus doesn't realize that the template
name actually has the fully qualified name NS1::NS2::Templ1.
replace_typedefs_qualified_name calls into replace_typedefs on the
template node, and that ends up in inspect_type looking up for a
symbol named "Templ1", which finds the global namespace typedef, which
itself expands to NS1::NS2::Templ1. GDB then tries replacing typedefs
in that newly expanded name, which ends up again in
replace_typedefs_qualified_name, trying to expand a fully qualified
name with "NS::NS2::Templ1<unsigned>" in its name, which results in
recursion whenever the template node is reached.
Fix this by teaching replace_typedefs_qualified_name how to handle
template nodes. It needs handling in two places: the first spot
handles the symbol above; the second spot handles a symbol like this,
from the new test:
(gdb) b NS1::NS2::grab_it(NS1::NS2::Templ1<int>*)
d_dump tree for NS1::NS2::grab_it(NS1::NS2::Templ1<int>*):
typed name
qualified name
name 'NS1'
qualified name
name 'NS2'
name 'grab_it'
function type
argument list
pointer
qualified name
name 'NS1'
qualified name
name 'NS2'
template <<<<<<<<
name 'Templ1'
template argument list
builtin type int
What's different in this case is that the template node appears on the
right child node of a qualified name, instead of on the left child.
The testcase includes a test that checks whether template aliases are
correctly replaced by GDB too. That fails with GCC due to GCC PR
95437, which makes GDB not know about a typedef for
"NS1::NS2::AliasTempl<int>". GCC emits a typedef named
"NS1::NS2::AliasTempl" instead, with no template parameter info. The
test passes with Clang (5.0.2 at least). See more details here:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95437
gdb/ChangeLog:
2020-05-30 Pedro Alves <palves@redhat.com>
* cp-support.c (replace_typedefs_template): New.
(replace_typedefs_qualified_name): Handle
DEMANGLE_COMPONENT_TEMPLATE.
gdb/testsuite/ChangeLog:
2020-05-30 Pedro Alves <palves@redhat.com>
* gdb.linespec/cp-replace-typedefs-ns-template.cc: New.
* gdb.linespec/cp-replace-typedefs-ns-template.exp: New.
+2020-05-30 Pedro Alves <palves@redhat.com>
+
+ * cp-support.c (replace_typedefs_template): New.
+ (replace_typedefs_qualified_name): Handle
+ DEMANGLE_COMPONENT_TEMPLATE.
+
2020-05-29 Simon Marchi <simon.marchi@efficios.com>
* dwarf2/comp-unit.c, dwarf2/comp-unit.h, dwarf2/index-cache.c,
return 0;
}
+/* Helper for replace_typedefs_qualified_name to handle
+ DEMANGLE_COMPONENT_TEMPLATE. TMPL is the template node. BUF is
+ the buffer that holds the qualified name being built by
+ replace_typedefs_qualified_name. REPL is the node that will be
+ rewritten as a DEMANGLE_COMPONENT_NAME node holding the 'template
+ plus template arguments' name with typedefs replaced. */
+
+static bool
+replace_typedefs_template (struct demangle_parse_info *info,
+ string_file &buf,
+ struct demangle_component *tmpl,
+ struct demangle_component *repl,
+ canonicalization_ftype *finder,
+ void *data)
+{
+ demangle_component *tmpl_arglist = d_right (tmpl);
+
+ /* Replace typedefs in the template argument list. */
+ replace_typedefs (info, tmpl_arglist, finder, data);
+
+ /* Convert 'template + replaced template argument list' to a string
+ and replace the REPL node. */
+ gdb::unique_xmalloc_ptr<char> tmpl_str = cp_comp_to_string (tmpl, 100);
+ if (tmpl_str == nullptr)
+ {
+ /* If something went astray, abort typedef substitutions. */
+ return false;
+ }
+ buf.puts (tmpl_str.get ());
+
+ repl->type = DEMANGLE_COMPONENT_NAME;
+ repl->u.s_name.s = obstack_strdup (&info->obstack, buf.string ());
+ repl->u.s_name.len = buf.size ();
+ return true;
+}
+
/* Replace any typedefs appearing in the qualified name
(DEMANGLE_COMPONENT_QUAL_NAME) represented in RET_COMP for the name parse
given in INFO. */
substituted name. */
while (comp->type == DEMANGLE_COMPONENT_QUAL_NAME)
{
+ if (d_left (comp)->type == DEMANGLE_COMPONENT_TEMPLATE)
+ {
+ /* Convert 'template + replaced template argument list' to a
+ string and replace the top DEMANGLE_COMPONENT_QUAL_NAME
+ node. */
+ if (!replace_typedefs_template (info, buf,
+ d_left (comp), d_left (ret_comp),
+ finder, data))
+ return;
+
+ buf.clear ();
+ d_right (ret_comp) = d_right (comp);
+ comp = ret_comp;
+
+ /* Fallback to DEMANGLE_COMPONENT_NAME processing. We want
+ to call inspect_type for this template, in case we have a
+ template alias, like:
+ template<typename T> using alias = base<int, t>;
+ in which case we want inspect_type to do a replacement like:
+ alias<int> -> base<int, int>
+ */
+ }
+
if (d_left (comp)->type == DEMANGLE_COMPONENT_NAME)
{
struct demangle_component newobj;
comp = d_right (comp);
}
- /* If the next component is DEMANGLE_COMPONENT_NAME, save the qualified
- name assembled above and append the name given by COMP. Then use this
- reassembled name to check for a typedef. */
+ /* If the next component is DEMANGLE_COMPONENT_TEMPLATE or
+ DEMANGLE_COMPONENT_NAME, save the qualified name assembled above
+ and append the name given by COMP. Then use this reassembled
+ name to check for a typedef. */
- if (comp->type == DEMANGLE_COMPONENT_NAME)
+ if (comp->type == DEMANGLE_COMPONENT_TEMPLATE)
+ {
+ /* Replace the top (DEMANGLE_COMPONENT_QUAL_NAME) node with a
+ DEMANGLE_COMPONENT_NAME node containing the whole name. */
+ if (!replace_typedefs_template (info, buf, comp, ret_comp, finder, data))
+ return;
+ inspect_type (info, ret_comp, finder, data);
+ }
+ else if (comp->type == DEMANGLE_COMPONENT_NAME)
{
buf.write (comp->u.s_name.s, comp->u.s_name.len);
+2020-05-30 Pedro Alves <palves@redhat.com>
+
+ * gdb.linespec/cp-replace-typedefs-ns-template.cc: New.
+ * gdb.linespec/cp-replace-typedefs-ns-template.exp: New.
+
2020-05-29 Gary Benson <gbenson@redhat.com>
* gdb.compile/compile-cplus.exp (additional_flags): Also
--- /dev/null
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2019-2020 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/>. */
+
+namespace NS1 {
+
+namespace NS2 {
+
+struct object
+{
+ object ()
+ {
+ }
+};
+
+typedef object *object_p;
+
+template<typename T>
+struct Templ1
+{
+ explicit Templ1 (object_p)
+ {
+ }
+
+ template<typename I>
+ static void
+ static_method (object_p)
+ {
+ }
+};
+
+template<typename T, typename U>
+struct Templ2
+{
+ explicit Templ2 (object_p)
+ {
+ }
+
+ template<typename I>
+ static void
+ static_method (object_p)
+ {
+ }
+};
+
+template<typename T> using AliasTempl = Templ2<int, T>;
+
+typedef Templ1<int> int_Templ1_t;
+
+void
+object_p_func (object_p)
+{
+}
+
+void
+int_Templ1_t_func (int_Templ1_t *)
+{
+}
+
+} // namespace NS2
+
+} // namespace NS1
+
+/* These typedefs have the same name as some of the components within
+ NS1 that they alias to, on purpose, to try to confuse GDB and cause
+ recursion. */
+using NS2 = int;
+using object = NS1::NS2::object;
+using Templ1 = NS1::NS2::Templ1<unsigned>;
+using Templ2 = NS1::NS2::Templ2<long, long>;
+using AliasTempl = NS1::NS2::AliasTempl<int>;
+
+NS2 ns2_int = 0;
+object obj;
+Templ1 templ1 (0);
+NS1::NS2::int_Templ1_t int_templ1 (0);
+AliasTempl alias (0);
+
+int
+main ()
+{
+ NS1::NS2::Templ1<int>::static_method<int> (0);
+ NS1::NS2::AliasTempl<int>::static_method<int> (0);
+ NS1::NS2::object_p_func (0);
+ NS1::NS2::int_Templ1_t_func (0);
+
+ return 0;
+}
--- /dev/null
+# Copyright 2020 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/>.
+
+# This file tests GDB's ability to replace typedefs in C++ symbols
+# when setting breakpoints, particularly around templates in
+# namespaces.
+
+load_lib completion-support.exp
+
+standard_testfile .cc
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
+ {debug c++ additional_flags=-std=c++11}]} {
+ return -1
+}
+
+# Disable the completion limit for the whole testcase.
+gdb_test_no_output "set max-completions unlimited"
+
+# Confirm that the important global namespace typedefs were indeed
+# emited in the debug info.
+gdb_test "ptype NS2" "type = int"
+gdb_test "ptype object" "type = struct NS1::NS2::object {.*"
+gdb_test "ptype Templ1" "type = struct NS1::NS2::Templ1<unsigned int> .*"
+gdb_test "ptype AliasTempl" "type = struct NS1::NS2::Templ2<int, int> .*"
+
+# Wrapper around check_bp_locations_match_list that expect a single
+# location in the set breakpoint, instead of a list of locations. If
+# the set location isn't specified, then it is assumed to be the exact
+# same as the input location.
+proc check_bp {location_in {location_out ""}} {
+ if {$location_out == ""} {
+ set location_out $location_in
+ }
+ check_bp_locations_match_list "b $location_in" [list $location_out]
+}
+
+# These used to crash GDB with infinite recursion because GDB would
+# confuse the "Templ1" typedef in the global namespace with the "Templ1"
+# template in within NS1::NS2.
+test_gdb_complete_unique \
+ "break NS1::NS2::Templ1<int>::Tem" \
+ "break NS1::NS2::Templ1<int>::Templ1(NS1::NS2::object*)"
+check_bp "NS1::NS2::Templ1<int>::Templ1(NS1::NS2::object*)"
+
+# Similar test, but without a template. This would not crash.
+test_gdb_complete_unique \
+ "break NS1::NS2::object::obj" \
+ "break NS1::NS2::object::object()"
+check_bp "NS1::NS2::object::object()"
+
+# Test some non-template typedef replacing within a namespace.
+test_gdb_complete_unique \
+ "break NS1::NS2::object_p_f" \
+ "break NS1::NS2::object_p_func(NS1::NS2::object*)"
+check_bp \
+ "NS1::NS2::object_p_func(NS1::NS2::object_p)" \
+ "NS1::NS2::object_p_func(NS1::NS2::object*)"
+
+# Make sure the "NS2" in the template argument list is resolved as
+# being a global typedef for int.
+foreach loc {
+ "NS1::NS2::Templ1<int>::static_method<int>(NS1::NS2::object*)"
+ "NS1::NS2::Templ1<int>::static_method<NS2>(NS1::NS2::object*)"
+ "NS1::NS2::Templ1<NS2>::static_method<int>(NS1::NS2::object*)"
+ "NS1::NS2::Templ1<NS2>::static_method<NS2>(NS1::NS2::object*)"
+} {
+ check_bp $loc "NS1::NS2::Templ1<int>::static_method<int>(NS1::NS2::object*)"
+}
+
+foreach loc {
+ "NS1::NS2::Templ2<int, int>::static_method<int>(NS1::NS2::object*)"
+ "NS1::NS2::Templ2<int, int>::static_method<int>(NS1::NS2::object_p)"
+} {
+ check_bp $loc "NS1::NS2::Templ2<int, int>::static_method<int>(NS1::NS2::object*)"
+}
+
+# Check that GDB expands the "NS1::NS2::AliasTempl<int>" as
+# "NS1::NS2::Templ2<int, int>".
+foreach loc {
+ "NS1::NS2::AliasTempl<int>::static_method<int>(NS1::NS2::object*)"
+ "NS1::NS2::AliasTempl<int>::static_method<int>(NS1::NS2::object_p)"
+} {
+ if [test_compiler_info gcc*] {
+ # While Clang emits "AliasTempl<int>" (etc.) typedefs, GCC
+ # emits "AliasTempl" typedefs with no template parameter info.
+ setup_xfail gcc/95437 *-*-*
+ }
+ check_bp $loc "NS1::NS2::Templ2<int, int>::static_method<int>(NS1::NS2::object*)"
+
+ # Check that setting the breakpoint with GCC really failed,
+ # instead of succeeding with e.g., "AliasTempl<int>" preserved in
+ # the location text. If that ever happens, we'll need to update
+ # these tests.
+ if [test_compiler_info gcc*] {
+ check_setting_bp_fails "b $loc"
+ }
+}
+
+# Check typedef substitution in a template in a qualified name in a
+# function parameter list. These used to crash GDB with recursion
+# around "Templ1", because there's a "Templ1" typedef in the global
+# namespace.
+foreach loc {
+ "NS1::NS2::int_Templ1_t_func(NS1::NS2::int_Templ1_t*)"
+ "NS1::NS2::int_Templ1_t_func(NS1::NS2::Templ1<int>*)"
+} {
+ check_bp $loc "NS1::NS2::int_Templ1_t_func(NS1::NS2::Templ1<int>*)"
+}
projects / binutils-gdb.git / commitdiff