[2,PR,gdb/16959] gdb hangs in infinite recursion
Commit Message
The original problem was fixed (see related PR 22242). But using a typedef
as the declared type for a static member variable, as commented in this PR,
is still causing gdb to get into infinite loop when printing the static
member's value. This problem can be reproduced as follows:
% cat t.cc
class A {
typedef A type;
public:
bool operator==(const type& other) { return true; }
static const type INSTANCE;
};
const A A::INSTANCE;
int main() {
A a;
if (a == A::INSTANCE) {
return -1;
}
return 0;
}
% g++ -g t.cc
% gdb -ex "start" -ex "p a" a.out
The fix is rather trivial - in cp_print_static_field(), should call
check_typedef() to get the static member's real type and use it to
check whether it's a struct or an array.
Added a new test case to the testsuite as Simon suggested.
Tested on both aarch64-linux-gnu and amd64-linux-gnu. No regressions.
---
---
gdb/ChangeLog | 7 ++++
gdb/cp-valprint.c | 2 +-
gdb/testsuite/ChangeLog | 5 +++
gdb/testsuite/gdb.cp/static-typedef-print.cc | 35 +++++++++++++++++++++
gdb/testsuite/gdb.cp/static-typedef-print.exp | 40 +++++++++++++++++++++++++
5 files changed, 88 insertions(+), 1 deletions(-)
create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.cc
create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.exp
Comments
On 2018-03-22 01:41 PM, Weimin Pan wrote:
> The original problem was fixed (see related PR 22242). But using a typedef
> as the declared type for a static member variable, as commented in this PR,
> is still causing gdb to get into infinite loop when printing the static
> member's value. This problem can be reproduced as follows:
>
> % cat t.cc
> class A {
> typedef A type;
> public:
> bool operator==(const type& other) { return true; }
>
> static const type INSTANCE;
> };
>
> const A A::INSTANCE;
>
> int main() {
> A a;
> if (a == A::INSTANCE) {
> return -1;
> }
> return 0;
> }
> % g++ -g t.cc
> % gdb -ex "start" -ex "p a" a.out
>
> The fix is rather trivial - in cp_print_static_field(), should call
> check_typedef() to get the static member's real type and use it to
> check whether it's a struct or an array.
>
> Added a new test case to the testsuite as Simon suggested.
>
> Tested on both aarch64-linux-gnu and amd64-linux-gnu. No regressions.
> ---
> ---
> gdb/ChangeLog | 7 ++++
> gdb/cp-valprint.c | 2 +-
> gdb/testsuite/ChangeLog | 5 +++
> gdb/testsuite/gdb.cp/static-typedef-print.cc | 35 +++++++++++++++++++++
> gdb/testsuite/gdb.cp/static-typedef-print.exp | 40 +++++++++++++++++++++++++
> 5 files changed, 88 insertions(+), 1 deletions(-)
> create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.cc
> create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.exp
>
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index d0a8dfd..6fd43de 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,10 @@
> +2018-02-07 Weimin Pan <weimin.pan@oracle.com>
> +
> + PR gdb/16959
> + * cp-valprint.c: (cp_print_static_field) Use check_typedef() to get
> + static member's real type for TYPE_CODE_STRUCT and TYPE_CODE_ARRAY
> + comparisons.
> +
> 2018-01-24 Pedro Alves <palves@redhat.com>
>
> GCC PR libstdc++/83906
> diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
> index 486653f..0370b56 100644
> --- a/gdb/cp-valprint.c
> +++ b/gdb/cp-valprint.c
> @@ -633,6 +633,7 @@ cp_print_static_field (struct type *type,
> return;
> }
>
> + type = check_typedef (type);
> if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
> {
> CORE_ADDR *first_dont_print;
> @@ -658,7 +659,6 @@ cp_print_static_field (struct type *type,
> addr = value_address (val);
> obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
> sizeof (CORE_ADDR));
> - type = check_typedef (type);
> cp_print_value_fields (type, value_enclosing_type (val),
> value_embedded_offset (val), addr,
> stream, recurse, val,
I pointed this out in my previous mail:
type is passed below to val_print. I think it would be better to continue
passing the original type to that function instead of the resolved type. It
could affect how things are printed (if the type name is printed somewhere,
or if pretty printers are involved). Many functions use a variable "real_type"
to hold the result from check_typedef, you could follow that pattern.
Did you have a chance to take a look?
Simon
On 3/22/2018 1:27 PM, Simon Marchi wrote:
> On 2018-03-22 01:41 PM, Weimin Pan wrote:
>> The original problem was fixed (see related PR 22242). But using a typedef
>> as the declared type for a static member variable, as commented in this PR,
>> is still causing gdb to get into infinite loop when printing the static
>> member's value. This problem can be reproduced as follows:
>>
>> % cat t.cc
>> class A {
>> typedef A type;
>> public:
>> bool operator==(const type& other) { return true; }
>>
>> static const type INSTANCE;
>> };
>>
>> const A A::INSTANCE;
>>
>> int main() {
>> A a;
>> if (a == A::INSTANCE) {
>> return -1;
>> }
>> return 0;
>> }
>> % g++ -g t.cc
>> % gdb -ex "start" -ex "p a" a.out
>>
>> The fix is rather trivial - in cp_print_static_field(), should call
>> check_typedef() to get the static member's real type and use it to
>> check whether it's a struct or an array.
>>
>> Added a new test case to the testsuite as Simon suggested.
>>
>> Tested on both aarch64-linux-gnu and amd64-linux-gnu. No regressions.
>> ---
>> ---
>> gdb/ChangeLog | 7 ++++
>> gdb/cp-valprint.c | 2 +-
>> gdb/testsuite/ChangeLog | 5 +++
>> gdb/testsuite/gdb.cp/static-typedef-print.cc | 35 +++++++++++++++++++++
>> gdb/testsuite/gdb.cp/static-typedef-print.exp | 40 +++++++++++++++++++++++++
>> 5 files changed, 88 insertions(+), 1 deletions(-)
>> create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.cc
>> create mode 100644 gdb/testsuite/gdb.cp/static-typedef-print.exp
>>
>> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
>> index d0a8dfd..6fd43de 100644
>> --- a/gdb/ChangeLog
>> +++ b/gdb/ChangeLog
>> @@ -1,3 +1,10 @@
>> +2018-02-07 Weimin Pan <weimin.pan@oracle.com>
>> +
>> + PR gdb/16959
>> + * cp-valprint.c: (cp_print_static_field) Use check_typedef() to get
>> + static member's real type for TYPE_CODE_STRUCT and TYPE_CODE_ARRAY
>> + comparisons.
>> +
>> 2018-01-24 Pedro Alves <palves@redhat.com>
>>
>> GCC PR libstdc++/83906
>> diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
>> index 486653f..0370b56 100644
>> --- a/gdb/cp-valprint.c
>> +++ b/gdb/cp-valprint.c
>> @@ -633,6 +633,7 @@ cp_print_static_field (struct type *type,
>> return;
>> }
>>
>> + type = check_typedef (type);
>> if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
>> {
>> CORE_ADDR *first_dont_print;
>> @@ -658,7 +659,6 @@ cp_print_static_field (struct type *type,
>> addr = value_address (val);
>> obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
>> sizeof (CORE_ADDR));
>> - type = check_typedef (type);
>> cp_print_value_fields (type, value_enclosing_type (val),
>> value_embedded_offset (val), addr,
>> stream, recurse, val,
> I pointed this out in my previous mail:
>
> type is passed below to val_print. I think it would be better to continue
> passing the original type to that function instead of the resolved type. It
> could affect how things are printed (if the type name is printed somewhere,
> or if pretty printers are involved). Many functions use a variable "real_type"
> to hold the result from check_typedef, you could follow that pattern.
>
> Did you have a chance to take a look?
>
> Simon
Sorry, I missed it. Will take a look.
Thanks,
Weimin
@@ -1,3 +1,10 @@
+2018-02-07 Weimin Pan <weimin.pan@oracle.com>
+
+ PR gdb/16959
+ * cp-valprint.c: (cp_print_static_field) Use check_typedef() to get
+ static member's real type for TYPE_CODE_STRUCT and TYPE_CODE_ARRAY
+ comparisons.
+
2018-01-24 Pedro Alves <palves@redhat.com>
GCC PR libstdc++/83906
@@ -633,6 +633,7 @@ cp_print_static_field (struct type *type,
return;
}
+ type = check_typedef (type);
if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
{
CORE_ADDR *first_dont_print;
@@ -658,7 +659,6 @@ cp_print_static_field (struct type *type,
addr = value_address (val);
obstack_grow (&dont_print_statmem_obstack, (char *) &addr,
sizeof (CORE_ADDR));
- type = check_typedef (type);
cp_print_value_fields (type, value_enclosing_type (val),
value_embedded_offset (val), addr,
stream, recurse, val,
@@ -1,3 +1,8 @@
+2018-03-20 Weimin Pan <weimin.pan@oracle.com>
+
+ * gdb.cp/static-typedef-print.exp: New file.
+ * gdb.cp/static-typedef-print.cc: New file.
+
2018-01-22 Pedro Alves <palves@redhat.com>
Sergio Durigan Junior <sergiodj@redhat.com>
new file mode 100644
@@ -0,0 +1,35 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ 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/>. */
+
+class A {
+ typedef A type;
+public:
+ bool operator==(const type& other) { return true; }
+
+ static const type INSTANCE;
+};
+
+const A A::INSTANCE = {};
+
+int main() {
+ A a;
+ if (a == A::INSTANCE) {
+ return -1;
+ }
+ return 0;
+}
+
new file mode 100644
@@ -0,0 +1,40 @@
+# 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] } { continue }
+
+standard_testfile .cc
+
+if [get_compiler_info "c++"] {
+ return -1
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
+ return -1
+}
+
+clean_restart $testfile
+
+if ![runto_main] {
+ untested "could not run to main"
+ return -1
+}
+
+gdb_test "print a" \
+ "static INSTANCE = <same as static member of an already seen type>}}.*" \
+ "print static member"
+
+gdb_exit
+return 0