Fix crash in cp_print_value_fields
Commit Message
From: Tom Tromey <tom@tromey.com>
PR c++/20020 concerns a crash in cp_print_value_fields. The immediate
cause is that cp_print_value_fields does not handle the case where
value_static_field fails. This is fixed in this patch by calling
cp_print_static_field from the "try" block.
Digging a bit deeper, the error occurs because GCC does not emit a
DW_AT_const_value for a static constexpr member appearing in a
template class. I've filed a GCC bug for this.
Tested on x86-64 Fedora 29.
gdb/ChangeLog
2019-05-17 Tom Tromey <tromey@adacore.com>
PR c++/20020:
* cp-valprint.c (cp_print_value_fields): Call
cp_print_static_field inside "try".
gdb/testsuite/ChangeLog
2019-05-17 Tom Tromey <tromey@adacore.com>
PR c++/20020:
* gdb.cp/constexpr-field.exp: New file.
* gdb.cp/constexpr-field.cc: New file.
---
gdb/ChangeLog | 6 ++++
gdb/cp-valprint.c | 12 ++++----
gdb/testsuite/ChangeLog | 6 ++++
gdb/testsuite/gdb.cp/constexpr-field.cc | 37 ++++++++++++++++++++++++
gdb/testsuite/gdb.cp/constexpr-field.exp | 36 +++++++++++++++++++++++
5 files changed, 90 insertions(+), 7 deletions(-)
create mode 100644 gdb/testsuite/gdb.cp/constexpr-field.cc
create mode 100644 gdb/testsuite/gdb.cp/constexpr-field.exp
Comments
Tom> 2019-05-17 Tom Tromey <tromey@adacore.com>
Tom> PR c++/20020:
Tom> * cp-valprint.c (cp_print_value_fields): Call
Tom> cp_print_static_field inside "try".
I'm checking this in now.
Tom
On 5/17/19 9:18 PM, Tom Tromey wrote:
> +# "x" sometimes isn't available due to
> +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90526
> +gdb_test "print x" " = {static f = .*}"
> +
How about making that expect the correct value, and then use
"setup_xfail gcc/90526" ?
Thanks,
Pedro Alves
On 17-05-19 22:18, Tom Tromey wrote:
> From: Tom Tromey <tom@tromey.com>
>
> PR c++/20020 concerns a crash in cp_print_value_fields. The immediate
> cause is that cp_print_value_fields does not handle the case where
> value_static_field fails. This is fixed in this patch by calling
> cp_print_static_field from the "try" block.
>
> Digging a bit deeper, the error occurs because GCC does not emit a
> DW_AT_const_value for a static constexpr member appearing in a
> template class. I've filed a GCC bug for this.
>
> Tested on x86-64 Fedora 29.
>
> gdb/ChangeLog
> 2019-05-17 Tom Tromey <tromey@adacore.com>
>
> PR c++/20020:
> * cp-valprint.c (cp_print_value_fields): Call
> cp_print_static_field inside "try".
>
> gdb/testsuite/ChangeLog
> 2019-05-17 Tom Tromey <tromey@adacore.com>
>
> PR c++/20020:
> * gdb.cp/constexpr-field.exp: New file.
> * gdb.cp/constexpr-field.cc: New file.
> ---
> gdb/ChangeLog | 6 ++++
> gdb/cp-valprint.c | 12 ++++----
> gdb/testsuite/ChangeLog | 6 ++++
> gdb/testsuite/gdb.cp/constexpr-field.cc | 37 ++++++++++++++++++++++++
> gdb/testsuite/gdb.cp/constexpr-field.exp | 36 +++++++++++++++++++++++
> 5 files changed, 90 insertions(+), 7 deletions(-)
> create mode 100644 gdb/testsuite/gdb.cp/constexpr-field.cc
> create mode 100644 gdb/testsuite/gdb.cp/constexpr-field.exp
>
> diff --git a/gdb/cp-valprint.c b/gdb/cp-valprint.c
> index ff860df499a..d8d5c06fd1e 100644
> --- a/gdb/cp-valprint.c
> +++ b/gdb/cp-valprint.c
> @@ -329,22 +329,20 @@ cp_print_value_fields (struct type *type, struct type *real_type,
> }
> else if (field_is_static (&TYPE_FIELD (type, i)))
> {
> - struct value *v = NULL;
> -
> try
> {
> - v = value_static_field (type, i);
> - }
> + struct value *v = value_static_field (type, i);
>
> + cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> + v, stream, recurse + 1,
> + options);
> + }
Here options is used ...
> catch (const gdb_exception_error &ex)
> {
> fprintf_filtered (stream,
> _("<error reading variable: %s>"),
> ex.what ());
> }
> -
> - cp_print_static_field (TYPE_FIELD_TYPE (type, i),
> - v, stream, recurse + 1, opts);
while here opts used to be used.
Is this change intentional? It's not mentioned anywhere.
Thanks,
- Tom
> }
> else if (i == vptr_fieldno && type == vptr_basetype)
> {
>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:
Pedro> On 5/17/19 9:18 PM, Tom Tromey wrote:
>> +# "x" sometimes isn't available due to
>> +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90526
>> +gdb_test "print x" " = {static f = .*}"
>> +
Pedro> How about making that expect the correct value, and then use
Pedro> "setup_xfail gcc/90526" ?
Sorry about the delay on this. I made this change, and I'll send it soon.
Tom
>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:
>> + cp_print_static_field (TYPE_FIELD_TYPE (type, i),
>> + v, stream, recurse + 1,
>> + options);
>> + }
Tom> Here options is used ...
>> catch (const gdb_exception_error &ex)
>> {
>> fprintf_filtered (stream,
>> _("<error reading variable: %s>"),
>> ex.what ());
>> }
>> -
>> - cp_print_static_field (TYPE_FIELD_TYPE (type, i),
>> - v, stream, recurse + 1, opts);
Tom> while here opts used to be used.
Tom> Is this change intentional? It's not mentioned anywhere.
Thanks for catching that. It was not intentional. I'll send a fix shortly.
Tom
@@ -329,22 +329,20 @@ cp_print_value_fields (struct type *type, struct type *real_type,
}
else if (field_is_static (&TYPE_FIELD (type, i)))
{
- struct value *v = NULL;
-
try
{
- v = value_static_field (type, i);
- }
+ struct value *v = value_static_field (type, i);
+ cp_print_static_field (TYPE_FIELD_TYPE (type, i),
+ v, stream, recurse + 1,
+ options);
+ }
catch (const gdb_exception_error &ex)
{
fprintf_filtered (stream,
_("<error reading variable: %s>"),
ex.what ());
}
-
- cp_print_static_field (TYPE_FIELD_TYPE (type, i),
- v, stream, recurse + 1, opts);
}
else if (i == vptr_fieldno && type == vptr_basetype)
{
new file mode 100644
@@ -0,0 +1,37 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2019 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/>. */
+
+template<typename T>
+struct X
+{
+ static constexpr bool f = true;
+};
+
+X<int> x;
+
+struct Y
+{
+ static constexpr bool f = true;
+};
+
+Y y;
+
+int
+main (void)
+{
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,36 @@
+# Copyright 2019 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 is part of the gdb testsuite.
+
+if {[skip_cplus_tests]} { continue }
+
+standard_testfile .cc
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
+ {c++ debug additional_flags=-std=c++17}]} {
+ return -1
+}
+
+if {![runto_main]} {
+ perror "couldn't run to breakpoint"
+ continue
+}
+
+# "x" sometimes isn't available due to
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90526
+gdb_test "print x" " = {static f = .*}"
+
+gdb_test "print y" " = {static f = true}"