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Re: [PATCH] Fix crash in cp_print_value_fields
- From: Tom de Vries <tdevries at suse dot de>
- To: Tom Tromey <tromey at adacore dot com>, gdb-patches at sourceware dot org
- Cc: Tom Tromey <tom at tromey dot com>
- Date: Tue, 18 Jun 2019 15:50:29 +0200
- Subject: Re: [PATCH] Fix crash in cp_print_value_fields
- References: <20190517201814.27951-1-tromey@adacore.com>
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)
> {