Re: [PATCHv2] gdb/mi: New commands to catch C++ exceptions

[Tom de Vries <tdevries@suse.de>]

On 16-06-19 17:29, Andrew Burgess wrote:
> * Tom de Vries <tdevries@suse.de> [2019-06-16 15:14:06 +0200]:
> 
>> On 16-06-19 00:34, Andrew Burgess wrote:
>>> * Andrew Burgess <andrew.burgess@embecosm.com> [2019-05-12 00:46:46 +0100]:
>>>
>>>> Eli,
>>>>
>>>> This iteration includes updated documentation that fixes almost all of
>>>> the issues you raised.  The only thing I haven't done is collapse all
>>>> of the command sub-sections into a single sub-section.  I looked
>>>> through most of the existing MI commands and they all seem to be one
>>>> command per sub-section, so I wasn't entirely sure how to layout a
>>>> merged entry, nor if a merged entry was inline with the style for MI
>>>> commands.
>>>>
>>>> ---
>>>>
>>>> I have also tweaked the code a little in this version, the changes
>>>> around how a catchpoint is reported when it is initially setup has
>>>> changed, the output is not more inline with other breakpoints.  See
>>>> the changes in print_mention_exception_catchpoint, and the new
>>>> scoped_restore restore_breakpoint_reporting in
>>>> mi_cmd_catch_exception_event.  Otherwise the code is unchanged.
>>>>
>>>> Thanks,
>>>> Andrew
>>>>
>>>> ---
>>>>
>>>> Adds some MI commands to catch C++ exceptions.  The new commands are
>>>> -catch-throw, -catch-rethrow, and -catch-catch, these all correspond
>>>> to the CLI commands 'catch throw', 'catch rethrow', and 'catch catch'.
>>>>
>>>> Each MI command takes two optional arguments, '-t' has the effect of
>>>> calling 'tcatch' instead of 'catch', for example:
>>>>
>>>>    (gdb)
>>>>    -catch-throw -t
>>>>
>>>> Is the same as:
>>>>
>>>>    (gdb) tcatch throw
>>>>
>>>> There is also a '-r REGEXP' argument that can supply a regexp to match
>>>> against the exception type, so:
>>>>
>>>>    (gdb)
>>>>    -catch-catch -r PATTERN
>>>>
>>>> Is the same as:
>>>>
>>>>    (gdb) catch catch PATTERN
>>>>
>>>> The change in print_mention_exception_catchpoint might seem a little
>>>> strange; changing the output from using ui_out::field_int and
>>>> ui_out::text to using  ui_out::message.
>>>>
>>>> The print_mention_exception_catchpoint is used as the 'print_mention'
>>>> method for the exception catchpoint breakpoint object.  Most of the
>>>> other 'print_mention' methods (see breakpoint.c) use either
>>>> printf_filtered, of ui_out::message.  Using field_int was causing an
>>>> unexpected field to be added to the MI output.  Here's the output
>>>> without the change in print_mention_exception_catchpoint:
>>>>
>>>>     (gdb)
>>>>     -catch-throw
>>>>     ^done,bkptno="1",bkpt={number="1",type="breakpoint",disp="keep",
>>>>                            enabled="y",addr="0x00000000004006c0",
>>>>                            what="exception throw",catch-type="throw",
>>>>                            thread-groups=["i1"],times="0"}
>>>>
>>>> Notice the breakpoint number appears in both the 'bkptno' field, and
>>>> the 'number' field within the 'bkpt' tuple.  Here's the output with
>>>> the change in print_mention_exception_catchpoint:
>>>>
>>>>     (gdb)
>>>>     -catch-throw
>>>>     ^done,bkpt={number="1",type="breakpoint",disp="keep",
>>>>                 enabled="y",addr="0x00000000004006c0",
>>>>                 what="exception throw",catch-type="throw",
>>>>                 thread-groups=["i1"],times="0"}
>>>>
>>>> gdb/ChangeLog:
>>>>
>>>> 	* NEWS: Mention new MI commands.
>>>> 	* break-catch-throw.c (enum exception_event_kind): Move to
>>>> 	breakpoint.h.
>>>> 	(print_mention_exception_catchpoint): Output text as a single
>>>> 	message.
>>>> 	(catch_exception_command_1): Rename to...
>>>> 	(catch_exception_event): ...this, make non-static, update header
>>>> 	command, and change some parameter types.
>>>> 	(catch_catch_command): Update for changes to
>>>> 	catch_exception_command_1.
>>>> 	(catch_throw_command): Likewise.
>>>> 	(catch_rethrow_command): Likewise.
>>>> 	* breakpoint.c (enum exception_event_kind): Delete.
>>>> 	* breakpoint.h (enum exception_event_kind): Moved here from
>>>> 	break-catch-throw.c.
>>>> 	(catch_exception_event): Declare.
>>>> 	* mi/mi-cmd-catch.c (mi_cmd_catch_exception_event): New function.
>>>> 	(mi_cmd_catch_throw): New function.
>>>> 	(mi_cmd_catch_rethrow): New function.
>>>> 	(mi_cmd_catch_catch): New function.
>>>> 	* mi/mi-cmds.c (mi_cmds): Add 'catch-throw', 'catch-rethrow', and
>>>> 	'catch-catch' entries.
>>>> 	* mi/mi-cmds.h (mi_cmd_catch_throw): Declare.
>>>> 	(mi_cmd_catch_rethrow): Declare.
>>>> 	(mi_cmd_catch_catch): Declare.
>>>>
>>>> gdb/doc/ChangeLog:
>>>>
>>>> 	* gdb.texinfo (GDB/MI Catchpoint Commands): Add menu entry to new
>>>> 	node.
>>>> 	(C++ Exception GDB/MI Catchpoint Commands): New node to describe
>>>> 	new MI commands.
>>>>
>>>> gdb/testsuite/ChangeLog:
>>>>
>>>> 	* gdb.mi/mi-catch-cpp-exceptions.cc: New file.
>>>> 	* gdb.mi/mi-catch-cpp-exceptions.exp: New file.
>>>> 	* lib/mi-support.exp (mi_expect_stop): Handle 'exception-caught'
>>>> 	as a stop reason.
>>>
>>> I've now pushed this patch with the doc fixes that Eli suggested.
>>>
>>
>> I've filed PR24686 - "FAIL: gdb.mi/mi-catch-cpp-exceptions.exp: all with
>> invalid regexp: run until breakpoint in main (timeout)"
> 
> Thanks for reporting this.
> 
> I have pushed the patch below which I believe should change the FAIL
> you are seeing into a KFAIL.
> 
> Let me know if this helps.
> 

Hi,

that works, I see a KFAIL now.

Thanks,
- Tom

> Thanks,
> Andrew
> 
> --
> 
> commit 93cb9841d68263174a600dc70af742a8e2eabfc6
> Author: Andrew Burgess <andrew.burgess@embecosm.com>
> Date:   Sun Jun 16 16:17:59 2019 +0100
> 
>     gdb/testsuite: Improve detection of bug gdb/24541
>     
>     In bug gdb/24686 a testsuite failure was reported, this failure was
>     actually just another instance of bug gdb/24541, however, due to the
>     non-deterministic nature of bug gdb/24541 the testsuite pattern that
>     was intended to catch this bug failed.
>     
>     This commit adds a second pattern to help detect gdb/24541, which
>     should change the FAIL reported in gdb/24686 into a KFAIL.
>     
>     gdb/testsuite/ChangeLog:
>     
>             PR gdb/24686
>             * gdb.mi/mi-catch-cpp-exceptions.exp: Add an extra pattern to
>             improve detection of bug gdb/24541.
> 
> diff --git a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> index b5dfbe68c1a..fa5b11e3e58 100644
> --- a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> +++ b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> @@ -141,6 +141,9 @@ with_test_prefix "all with invalid regexp" {
>  	-re "could not find minimal symbol for typeinfo address.*$mi_gdb_prompt$" {
>  	    kfail "gdb/24541" "${testname}"
>  	}
> +	-re "\\*stopped,bkptno=\"$decimal\",reason=\"breakpoint-hit\",disp=\"keep\".*func=\"__cxa_throw\".*$mi_gdb_prompt$" {
> +	    kfail "gdb/24541" "${testname}"
> +	}
>  	-re "\\*stopped,reason=\"breakpoint-hit\".*func=\"main\".*line=\"${main_lineno}\".*$mi_gdb_prompt$" {
>  	    pass "${testname}"
>  	}
>