[PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Tom de Vries]

Hi,

When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
for both the regexp argument, and the convenience variable $_exception (
https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).

Currently, when using these features with a libstdcxx without SDT probes, we
get the cryptic error message:
...
not stopped at a C++ exception catchpoint
...

Improve this by instead emitting the more helpful:
...
did not find exception probe (does libstdcxx have SDT probes?)
...

Tested on x86_64-linux.

OK for trunk?

Thanks,
- Tom

[gdb, c++] Improve error message when using libstdcxx without SDT probes

gdb/ChangeLog:

2019-07-25  Tom de Vries  <tdevries@suse.de>

	PR c++/24852
	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
	when pc_probe.prob == NULL.

gdb/testsuite/ChangeLog:

2019-07-25  Tom de Vries  <tdevries@suse.de>

	PR c++/24852
	* gdb.cp/no-libstdcxx-probe.exp: New test.

---
 gdb/break-catch-throw.c                     |  6 ++-
 gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 58 +++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
index 0677a55ee5..2d91285312 100644
--- a/gdb/break-catch-throw.c
+++ b/gdb/break-catch-throw.c
@@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
   unsigned n_args;
 
   pc_probe = find_probe_by_pc (pc);
-  if (pc_probe.prob == NULL
-      || pc_probe.prob->get_provider () != "libstdcxx"
+  if (pc_probe.prob == NULL)
+    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
+
+  if (pc_probe.prob->get_provider () != "libstdcxx"
       || (pc_probe.prob->get_name () != "catch"
 	  && pc_probe.prob->get_name () != "throw"
 	  && pc_probe.prob->get_name () != "rethrow"))
diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
new file mode 100644
index 0000000000..4c1a706ae0
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
@@ -0,0 +1,58 @@
+# 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/>.
+
+standard_testfile exceptprint.cc
+
+if {[skip_cplus_tests]} {
+    return -1
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+if {![runto_main]} {
+    return -1
+}
+
+set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
+
+if { $libstdcxx_probe_tests_supported == 1 } {
+    untested "Have libstdc++ stap probe"
+    return -1
+}
+
+proc do_continue_to_catchpoint {name} {
+    global gdb_prompt
+
+    gdb_test_multiple "continue" $name {
+	-re "Continuing.*Catchpoint \[0-9\].*\r\n$gdb_prompt $" {
+	    pass $name
+	}
+    }
+}
+
+proc do_exceptprint_tests {prefix output} {
+    with_test_prefix $prefix {
+	do_continue_to_catchpoint "continue to throw"
+	gdb_test "print \$_exception" \
+	    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"
+    }
+}
+
+gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \
+    "catch throw"
+
+do_exceptprint_tests string "$hex \"hi bob\""

Re: [PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Tom Tromey]

>>>>> "Tom" == Tom de Vries <tdevries@suse.de> writes:

Tom> When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
Tom> for both the regexp argument, and the convenience variable $_exception (
Tom> https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).

Tom> +  if (pc_probe.prob == NULL)
Tom> +    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));

I think it's more normal to start an error with a capital letter.
Also I'd suggest writing "libstdc++" here.

Ok with those changes.

thanks,
Tom

[PING][PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Tom de Vries]

On 25-07-19 23:04, Tom de Vries wrote:
> Hi,
> 
> When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
> for both the regexp argument, and the convenience variable $_exception (
> https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).
> 
> Currently, when using these features with a libstdcxx without SDT probes, we
> get the cryptic error message:
> ...
> not stopped at a C++ exception catchpoint
> ...
> 
> Improve this by instead emitting the more helpful:
> ...
> did not find exception probe (does libstdcxx have SDT probes?)
> ...
> 
> Tested on x86_64-linux.
> 
> OK for trunk?
> 

Ping.

Thanks,
- Tom

> [gdb, c++] Improve error message when using libstdcxx without SDT probes
> 
> gdb/ChangeLog:
> 
> 2019-07-25  Tom de Vries  <tdevries@suse.de>
> 
> 	PR c++/24852
> 	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
> 	when pc_probe.prob == NULL.
> 
> gdb/testsuite/ChangeLog:
> 
> 2019-07-25  Tom de Vries  <tdevries@suse.de>
> 
> 	PR c++/24852
> 	* gdb.cp/no-libstdcxx-probe.exp: New test.
> 
> ---
>  gdb/break-catch-throw.c                     |  6 ++-
>  gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 58 +++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
> index 0677a55ee5..2d91285312 100644
> --- a/gdb/break-catch-throw.c
> +++ b/gdb/break-catch-throw.c
> @@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
>    unsigned n_args;
>  
>    pc_probe = find_probe_by_pc (pc);
> -  if (pc_probe.prob == NULL
> -      || pc_probe.prob->get_provider () != "libstdcxx"
> +  if (pc_probe.prob == NULL)
> +    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
> +
> +  if (pc_probe.prob->get_provider () != "libstdcxx"
>        || (pc_probe.prob->get_name () != "catch"
>  	  && pc_probe.prob->get_name () != "throw"
>  	  && pc_probe.prob->get_name () != "rethrow"))
> diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
> new file mode 100644
> index 0000000000..4c1a706ae0
> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
> @@ -0,0 +1,58 @@
> +# 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/>.
> +
> +standard_testfile exceptprint.cc
> +
> +if {[skip_cplus_tests]} {
> +    return -1
> +}
> +
> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
> +    return -1
> +}
> +
> +if {![runto_main]} {
> +    return -1
> +}
> +
> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
> +
> +if { $libstdcxx_probe_tests_supported == 1 } {
> +    untested "Have libstdc++ stap probe"
> +    return -1
> +}
> +
> +proc do_continue_to_catchpoint {name} {
> +    global gdb_prompt
> +
> +    gdb_test_multiple "continue" $name {
> +	-re "Continuing.*Catchpoint \[0-9\].*\r\n$gdb_prompt $" {
> +	    pass $name
> +	}
> +    }
> +}
> +
> +proc do_exceptprint_tests {prefix output} {
> +    with_test_prefix $prefix {
> +	do_continue_to_catchpoint "continue to throw"
> +	gdb_test "print \$_exception" \
> +	    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"
> +    }
> +}
> +
> +gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \
> +    "catch throw"
> +
> +do_exceptprint_tests string "$hex \"hi bob\""
> 

[PING^2][PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Tom de Vries]

On 13-08-19 15:51, Tom de Vries wrote:
> On 25-07-19 23:04, Tom de Vries wrote:
>> Hi,
>>
>> When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
>> for both the regexp argument, and the convenience variable $_exception (
>> https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).
>>
>> Currently, when using these features with a libstdcxx without SDT probes, we
>> get the cryptic error message:
>> ...
>> not stopped at a C++ exception catchpoint
>> ...
>>
>> Improve this by instead emitting the more helpful:
>> ...
>> did not find exception probe (does libstdcxx have SDT probes?)
>> ...
>>
>> Tested on x86_64-linux.
>>
>> OK for trunk?
>>
> 

Ping^2.

Thanks,
- Tom

>> [gdb, c++] Improve error message when using libstdcxx without SDT probes
>>
>> gdb/ChangeLog:
>>
>> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>>
>> 	PR c++/24852
>> 	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
>> 	when pc_probe.prob == NULL.
>>
>> gdb/testsuite/ChangeLog:
>>
>> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>>
>> 	PR c++/24852
>> 	* gdb.cp/no-libstdcxx-probe.exp: New test.
>>
>> ---
>>  gdb/break-catch-throw.c                     |  6 ++-
>>  gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 58 +++++++++++++++++++++++++++++
>>  2 files changed, 62 insertions(+), 2 deletions(-)
>>
>> diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
>> index 0677a55ee5..2d91285312 100644
>> --- a/gdb/break-catch-throw.c
>> +++ b/gdb/break-catch-throw.c
>> @@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
>>    unsigned n_args;
>>  
>>    pc_probe = find_probe_by_pc (pc);
>> -  if (pc_probe.prob == NULL
>> -      || pc_probe.prob->get_provider () != "libstdcxx"
>> +  if (pc_probe.prob == NULL)
>> +    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
>> +
>> +  if (pc_probe.prob->get_provider () != "libstdcxx"
>>        || (pc_probe.prob->get_name () != "catch"
>>  	  && pc_probe.prob->get_name () != "throw"
>>  	  && pc_probe.prob->get_name () != "rethrow"))
>> diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
>> new file mode 100644
>> index 0000000000..4c1a706ae0
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
>> @@ -0,0 +1,58 @@
>> +# 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/>.
>> +
>> +standard_testfile exceptprint.cc
>> +
>> +if {[skip_cplus_tests]} {
>> +    return -1
>> +}
>> +
>> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
>> +    return -1
>> +}
>> +
>> +if {![runto_main]} {
>> +    return -1
>> +}
>> +
>> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
>> +
>> +if { $libstdcxx_probe_tests_supported == 1 } {
>> +    untested "Have libstdc++ stap probe"
>> +    return -1
>> +}
>> +
>> +proc do_continue_to_catchpoint {name} {
>> +    global gdb_prompt
>> +
>> +    gdb_test_multiple "continue" $name {
>> +	-re "Continuing.*Catchpoint \[0-9\].*\r\n$gdb_prompt $" {
>> +	    pass $name
>> +	}
>> +    }
>> +}
>> +
>> +proc do_exceptprint_tests {prefix output} {
>> +    with_test_prefix $prefix {
>> +	do_continue_to_catchpoint "continue to throw"
>> +	gdb_test "print \$_exception" \
>> +	    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"
>> +    }
>> +}
>> +
>> +gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \
>> +    "catch throw"
>> +
>> +do_exceptprint_tests string "$hex \"hi bob\""
>>

Re: [PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Sergio Durigan Junior]

On Thursday, July 25 2019, Tom de Vries wrote:

> Hi,
>
> When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
> for both the regexp argument, and the convenience variable $_exception (
> https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).
>
> Currently, when using these features with a libstdcxx without SDT probes, we
> get the cryptic error message:
> ...
> not stopped at a C++ exception catchpoint
> ...
>
> Improve this by instead emitting the more helpful:
> ...
> did not find exception probe (does libstdcxx have SDT probes?)
> ...
>
> Tested on x86_64-linux.
>
> OK for trunk?

Thanks for the patch.

> Thanks,
> - Tom
>
> [gdb, c++] Improve error message when using libstdcxx without SDT probes
>
> gdb/ChangeLog:
>
> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>
> 	PR c++/24852
> 	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
> 	when pc_probe.prob == NULL.
>
> gdb/testsuite/ChangeLog:
>
> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>
> 	PR c++/24852
> 	* gdb.cp/no-libstdcxx-probe.exp: New test.
>
> ---
>  gdb/break-catch-throw.c                     |  6 ++-
>  gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 58 +++++++++++++++++++++++++++++
>  2 files changed, 62 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
> index 0677a55ee5..2d91285312 100644
> --- a/gdb/break-catch-throw.c
> +++ b/gdb/break-catch-throw.c
> @@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
>    unsigned n_args;
>  
>    pc_probe = find_probe_by_pc (pc);
> -  if (pc_probe.prob == NULL
> -      || pc_probe.prob->get_provider () != "libstdcxx"
> +  if (pc_probe.prob == NULL)
> +    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
> +
> +  if (pc_probe.prob->get_provider () != "libstdcxx"
>        || (pc_probe.prob->get_name () != "catch"
>  	  && pc_probe.prob->get_name () != "throw"
>  	  && pc_probe.prob->get_name () != "rethrow"))
> diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
> new file mode 100644
> index 0000000000..4c1a706ae0
> --- /dev/null
> +++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
> @@ -0,0 +1,58 @@
> +# 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/>.
> +
> +standard_testfile exceptprint.cc
> +
> +if {[skip_cplus_tests]} {
> +    return -1
> +}
> +
> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
> +    return -1
> +}
> +
> +if {![runto_main]} {
> +    return -1
> +}
> +
> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]

Not your fault, but this reversed logic (skip_libstdcxx_probe_tests
returns 0 if the tests should be skipped) is kinda confusing.

> +
> +if { $libstdcxx_probe_tests_supported == 1 } {
> +    untested "Have libstdc++ stap probe"
> +    return -1
> +}
> +
> +proc do_continue_to_catchpoint {name} {
> +    global gdb_prompt
> +
> +    gdb_test_multiple "continue" $name {
> +	-re "Continuing.*Catchpoint \[0-9\].*\r\n$gdb_prompt $" {

You can use $decimal instead of \[0-9\] if you want.

> +	    pass $name
> +	}
> +    }
> +}
> +
> +proc do_exceptprint_tests {prefix output} {
> +    with_test_prefix $prefix {
> +	do_continue_to_catchpoint "continue to throw"
> +	gdb_test "print \$_exception" \
> +	    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"
> +    }
> +}

You don't seem to use $output here.

> +
> +gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \
> +    "catch throw"

$decimal if you want.

> +
> +do_exceptprint_tests string "$hex \"hi bob\""

The patch looks good to me.  Thanks for doing this.

-- 
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/

[committed][gdb/testsuite] Make skip_libstdcxx_probe_tests return 1 if true

[Tom de Vries]

[-- Attachment #1: Type: text/plain, Size: 426 bytes --]

[ was: Re: [PATCH][gdb, c++] Improve error message when using libstdcxx
without SDT probes ]

On 26-08-19 16:11, Sergio Durigan Junior wrote:
>> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
> Not your fault, but this reversed logic (skip_libstdcxx_probe_tests
> returns 0 if the tests should be skipped) is kinda confusing.
> 

It's also confusing me.

Fixed in attached patch.

Committed.

Thanks,
- Tom

[-- Attachment #2: 0001-gdb-testsuite-Make-skip_libstdcxx_probe_tests-return-1-if-true.patch --]
[-- Type: text/x-patch, Size: 2878 bytes --]

[gdb/testsuite] Make skip_libstdcxx_probe_tests return 1 if true

The tcl proc skip_libstdcxx_probe_tests currently returns 0 if the probe tests
need to be skipped, while tcl interprets 0 as false rather than true, which is
confusing.

Fix this by making skip_libstdcxx_probe_tests return 1 if the probe tests need
to be skipped.

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2019-08-26  Tom de Vries  <tdevries@suse.de>

	* lib/gdb.exp (skip_libstdcxx_probe_tests_prompt): Return 1 if probe
	* tests need to be skipped.
	* gdb.cp/exceptprint.exp: Update call to skip_libstdcxx_probe_tests.
	* gdb.mi/mi-catch-cpp-exceptions.exp: Update call to
	mi_skip_libstdcxx_probe_tests.

---
 gdb/testsuite/gdb.cp/exceptprint.exp             | 2 +-
 gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp | 2 +-
 gdb/testsuite/lib/gdb.exp                        | 9 +++++----
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/gdb/testsuite/gdb.cp/exceptprint.exp b/gdb/testsuite/gdb.cp/exceptprint.exp
index 46378d1b69..f6dcd0f5bd 100644
--- a/gdb/testsuite/gdb.cp/exceptprint.exp
+++ b/gdb/testsuite/gdb.cp/exceptprint.exp
@@ -27,7 +27,7 @@ if {![runto_main]} {
     return -1
 }
 
-if {![skip_libstdcxx_probe_tests]} {
+if {[skip_libstdcxx_probe_tests]} {
     untested "could not find libstdc++ stap probe"
     return -1
 }
diff --git a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
index 029dc1bd02..2951497882 100644
--- a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
+++ b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
@@ -36,7 +36,7 @@ mi_gdb_load ${binfile}
 if {![mi_run_to_main]} {
     return -1
 }
-set libstdcxx_probe_tests_supported [mi_skip_libstdcxx_probe_tests]
+set libstdcxx_probe_tests_supported [expr ![mi_skip_libstdcxx_probe_tests]]
 
 # Grab some line numbers we'll need.
 set catch_1_lineno [gdb_get_line_number "Catch 1"]
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index af56e8aa12..76805fb5ec 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -3158,20 +3158,21 @@ proc skip_unwinder_tests {} {
     return $ok
 }
 
-# Return 0 if we should skip tests that require the libstdc++ stap
+# Return 1 if we should skip tests that require the libstdc++ stap
 # probes.  This must be invoked while gdb is running, after shared
 # libraries have been loaded.  PROMPT_REGEXP is the expected prompt.
 
 proc skip_libstdcxx_probe_tests_prompt { prompt_regexp } {
-    set ok 0
+    set supported 0
     gdb_test_multiple "info probe" "check for stap probe in libstdc++" {
 	-re ".*libstdcxx.*catch.*\r\n$prompt_regexp" {
-	    set ok 1
+	    set supported 1
 	}
 	-re "\r\n$prompt_regexp" {
 	}
     } "$prompt_regexp"
-    return $ok
+    set skip [expr !$supported]
+    return $skip
 }
 
 # As skip_libstdcxx_probe_tests_prompt, with gdb_prompt.

Re: [committed][gdb/testsuite] Make skip_libstdcxx_probe_tests return 1 if true

[Sergio Durigan Junior]

On Monday, August 26 2019, Tom de Vries wrote:

> [ was: Re: [PATCH][gdb, c++] Improve error message when using libstdcxx
> without SDT probes ]
>
> On 26-08-19 16:11, Sergio Durigan Junior wrote:
>>> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
>> Not your fault, but this reversed logic (skip_libstdcxx_probe_tests
>> returns 0 if the tests should be skipped) is kinda confusing.
>> 
>
> It's also confusing me.
>
> Fixed in attached patch.

Aha, thanks!

> Committed.
>
> Thanks,
> - Tom
>
> [gdb/testsuite] Make skip_libstdcxx_probe_tests return 1 if true
>
> The tcl proc skip_libstdcxx_probe_tests currently returns 0 if the probe tests
> need to be skipped, while tcl interprets 0 as false rather than true, which is
> confusing.
>
> Fix this by making skip_libstdcxx_probe_tests return 1 if the probe tests need
> to be skipped.
>
> Tested on x86_64-linux.
>
> gdb/testsuite/ChangeLog:
>
> 2019-08-26  Tom de Vries  <tdevries@suse.de>
>
> 	* lib/gdb.exp (skip_libstdcxx_probe_tests_prompt): Return 1 if probe
> 	* tests need to be skipped.
> 	* gdb.cp/exceptprint.exp: Update call to skip_libstdcxx_probe_tests.
> 	* gdb.mi/mi-catch-cpp-exceptions.exp: Update call to
> 	mi_skip_libstdcxx_probe_tests.
>
> ---
>  gdb/testsuite/gdb.cp/exceptprint.exp             | 2 +-
>  gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp | 2 +-
>  gdb/testsuite/lib/gdb.exp                        | 9 +++++----
>  3 files changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/gdb/testsuite/gdb.cp/exceptprint.exp b/gdb/testsuite/gdb.cp/exceptprint.exp
> index 46378d1b69..f6dcd0f5bd 100644
> --- a/gdb/testsuite/gdb.cp/exceptprint.exp
> +++ b/gdb/testsuite/gdb.cp/exceptprint.exp
> @@ -27,7 +27,7 @@ if {![runto_main]} {
>      return -1
>  }
>  
> -if {![skip_libstdcxx_probe_tests]} {
> +if {[skip_libstdcxx_probe_tests]} {
>      untested "could not find libstdc++ stap probe"
>      return -1
>  }
> diff --git a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> index 029dc1bd02..2951497882 100644
> --- a/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> +++ b/gdb/testsuite/gdb.mi/mi-catch-cpp-exceptions.exp
> @@ -36,7 +36,7 @@ mi_gdb_load ${binfile}
>  if {![mi_run_to_main]} {
>      return -1
>  }
> -set libstdcxx_probe_tests_supported [mi_skip_libstdcxx_probe_tests]
> +set libstdcxx_probe_tests_supported [expr ![mi_skip_libstdcxx_probe_tests]]
>  
>  # Grab some line numbers we'll need.
>  set catch_1_lineno [gdb_get_line_number "Catch 1"]
> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> index af56e8aa12..76805fb5ec 100644
> --- a/gdb/testsuite/lib/gdb.exp
> +++ b/gdb/testsuite/lib/gdb.exp
> @@ -3158,20 +3158,21 @@ proc skip_unwinder_tests {} {
>      return $ok
>  }
>  
> -# Return 0 if we should skip tests that require the libstdc++ stap
> +# Return 1 if we should skip tests that require the libstdc++ stap
>  # probes.  This must be invoked while gdb is running, after shared
>  # libraries have been loaded.  PROMPT_REGEXP is the expected prompt.
>  
>  proc skip_libstdcxx_probe_tests_prompt { prompt_regexp } {
> -    set ok 0
> +    set supported 0
>      gdb_test_multiple "info probe" "check for stap probe in libstdc++" {
>  	-re ".*libstdcxx.*catch.*\r\n$prompt_regexp" {
> -	    set ok 1
> +	    set supported 1
>  	}
>  	-re "\r\n$prompt_regexp" {
>  	}
>      } "$prompt_regexp"
> -    return $ok
> +    set skip [expr !$supported]
> +    return $skip
>  }
>  
>  # As skip_libstdcxx_probe_tests_prompt, with gdb_prompt.
>

-- 
Sergio
GPG key ID: 237A 54B1 0287 28BF 00EF  31F4 D0EB 7628 65FC 5E36
Please send encrypted e-mail if possible
http://sergiodj.net/

Re: [PATCH][gdb, c++] Improve error message when using libstdcxx without SDT probes

[Tom de Vries]

[-- Attachment #1: Type: text/plain, Size: 4885 bytes --]

On 26-08-19 16:11, Sergio Durigan Junior wrote:
> On Thursday, July 25 2019, Tom de Vries wrote:
> 
>> Hi,
>>
>> When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
>> for both the regexp argument, and the convenience variable $_exception (
>> https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).
>>
>> Currently, when using these features with a libstdcxx without SDT probes, we
>> get the cryptic error message:
>> ...
>> not stopped at a C++ exception catchpoint
>> ...
>>
>> Improve this by instead emitting the more helpful:
>> ...
>> did not find exception probe (does libstdcxx have SDT probes?)
>> ...
>>
>> Tested on x86_64-linux.
>>
>> OK for trunk?
> 
> Thanks for the patch.
> 
>> Thanks,
>> - Tom
>>
>> [gdb, c++] Improve error message when using libstdcxx without SDT probes
>>
>> gdb/ChangeLog:
>>
>> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>>
>> 	PR c++/24852
>> 	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
>> 	when pc_probe.prob == NULL.
>>
>> gdb/testsuite/ChangeLog:
>>
>> 2019-07-25  Tom de Vries  <tdevries@suse.de>
>>
>> 	PR c++/24852
>> 	* gdb.cp/no-libstdcxx-probe.exp: New test.
>>
>> ---
>>  gdb/break-catch-throw.c                     |  6 ++-
>>  gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 58 +++++++++++++++++++++++++++++
>>  2 files changed, 62 insertions(+), 2 deletions(-)
>>
>> diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
>> index 0677a55ee5..2d91285312 100644
>> --- a/gdb/break-catch-throw.c
>> +++ b/gdb/break-catch-throw.c
>> @@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
>>    unsigned n_args;
>>  
>>    pc_probe = find_probe_by_pc (pc);
>> -  if (pc_probe.prob == NULL
>> -      || pc_probe.prob->get_provider () != "libstdcxx"
>> +  if (pc_probe.prob == NULL)
>> +    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
>> +
>> +  if (pc_probe.prob->get_provider () != "libstdcxx"
>>        || (pc_probe.prob->get_name () != "catch"
>>  	  && pc_probe.prob->get_name () != "throw"
>>  	  && pc_probe.prob->get_name () != "rethrow"))
>> diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
>> new file mode 100644
>> index 0000000000..4c1a706ae0
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
>> @@ -0,0 +1,58 @@
>> +# 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/>.
>> +
>> +standard_testfile exceptprint.cc
>> +
>> +if {[skip_cplus_tests]} {
>> +    return -1
>> +}
>> +
>> +if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
>> +    return -1
>> +}
>> +
>> +if {![runto_main]} {
>> +    return -1
>> +}
>> +
>> +set libstdcxx_probe_tests_supported [skip_libstdcxx_probe_tests]
> 
> Not your fault, but this reversed logic (skip_libstdcxx_probe_tests
> returns 0 if the tests should be skipped) is kinda confusing.
> 

[ FTR, dealt with here (
https://sourceware.org/ml/gdb-patches/2019-08/msg00595.html ). ]

>> +
>> +if { $libstdcxx_probe_tests_supported == 1 } {
>> +    untested "Have libstdc++ stap probe"
>> +    return -1
>> +}
>> +
>> +proc do_continue_to_catchpoint {name} {
>> +    global gdb_prompt
>> +
>> +    gdb_test_multiple "continue" $name {
>> +	-re "Continuing.*Catchpoint \[0-9\].*\r\n$gdb_prompt $" {
> 
> You can use $decimal instead of \[0-9\] if you want.
> 

Done.

>> +	    pass $name
>> +	}
>> +    }
>> +}
>> +
>> +proc do_exceptprint_tests {prefix output} {
>> +    with_test_prefix $prefix {
>> +	do_continue_to_catchpoint "continue to throw"
>> +	gdb_test "print \$_exception" \
>> +	    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"
>> +    }
>> +}
> 
> You don't seem to use $output here.
> 

Hmm, and also prefix doesn't make much sense. In fact, the code becomes
more clear if I just inline the procs, and replace the gdb_test_multiple
with gdb_test.

>> +
>> +gdb_test "catch throw" "Catchpoint \[0-9\]+ \\(throw\\)" \
>> +    "catch throw"
> 
> $decimal if you want.
> 

Done.

>> +
>> +do_exceptprint_tests string "$hex \"hi bob\""
> 
> The patch looks good to me.  Thanks for doing this.

Committed as below.

Thanks,
- Tom


[-- Attachment #2: 0001-gdb-c-Improve-error-message-when-using-libstdcxx-without-SDT-probes.patch --]
[-- Type: text/x-patch, Size: 3320 bytes --]

[gdb, c++] Improve error message when using libstdcxx without SDT probes

When using catch catch/rethrow/catch, a libstdcxx with SDT probes is required
for both the regexp argument, and the convenience variable $_exception (
https://sourceware.org/gdb/current/onlinedocs/gdb/Set-Catchpoints.html ).

Currently, when using these features with a libstdcxx without SDT probes, we
get the cryptic error message:
...
not stopped at a C++ exception catchpoint
...

Improve this by instead emitting the more helpful:
...
did not find exception probe (does libstdcxx have SDT probes?)
...

Tested on x86_64-linux.

gdb/ChangeLog:

2019-07-25  Tom de Vries  <tdevries@suse.de>

	PR c++/24852
	* break-catch-throw.c (fetch_probe_arguments): Improve error mesage
	when pc_probe.prob == NULL.

gdb/testsuite/ChangeLog:

2019-07-25  Tom de Vries  <tdevries@suse.de>

	PR c++/24852
	* gdb.cp/no-libstdcxx-probe.exp: New test.

---
 gdb/break-catch-throw.c                     |  6 +++--
 gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp | 41 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
index 0677a55ee5..2d91285312 100644
--- a/gdb/break-catch-throw.c
+++ b/gdb/break-catch-throw.c
@@ -106,8 +106,10 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
   unsigned n_args;
 
   pc_probe = find_probe_by_pc (pc);
-  if (pc_probe.prob == NULL
-      || pc_probe.prob->get_provider () != "libstdcxx"
+  if (pc_probe.prob == NULL)
+    error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
+
+  if (pc_probe.prob->get_provider () != "libstdcxx"
       || (pc_probe.prob->get_name () != "catch"
 	  && pc_probe.prob->get_name () != "throw"
 	  && pc_probe.prob->get_name () != "rethrow"))
diff --git a/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
new file mode 100644
index 0000000000..79826ea2d2
--- /dev/null
+++ b/gdb/testsuite/gdb.cp/no-libstdcxx-probe.exp
@@ -0,0 +1,41 @@
+# 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/>.
+
+standard_testfile exceptprint.cc
+
+if {[skip_cplus_tests]} {
+    return -1
+}
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug c++}]} {
+    return -1
+}
+
+if {![runto_main]} {
+    return -1
+}
+
+if { [skip_libstdcxx_probe_tests] == 0 } {
+    untested "Have libstdc++ stap probe"
+    return -1
+}
+
+gdb_test "catch throw" "Catchpoint $decimal \\(throw\\)" \
+    "catch throw"
+
+gdb_test "continue" "Continuing.*Catchpoint $decimal.*"
+
+gdb_test "print \$_exception" \
+    "did not find exception probe \\(does libstdcxx have SDT probes\\?\\).*"