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

[Andrew Burgess <andrew dot burgess at embecosm dot com>]

* 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.

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}"
 	}