* Re: What should a std::error_code pretty printer show?
2021-08-16 12:11 ` Jonathan Wakely
@ 2021-08-16 16:51 ` Jonathan Wakely
2021-08-16 19:30 ` Jonathan Wakely
0 siblings, 1 reply; 4+ messages in thread
From: Jonathan Wakely @ 2021-08-16 16:51 UTC (permalink / raw)
To: libstdc++; +Cc: gcc-patches
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On Mon, 16 Aug 2021 at 13:11, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>
>
>
> On Mon, 16 Aug 2021, 12:55 Jonathan Wakely, <jwakely.gcc@gmail.com> wrote:
>>
>> I'm adding a GDB printer for std::error_code.What I have now prints
>> the category name as a quoted string, followed by the error value:
>>
>> {"system": 0}
>> {"system": 1234}
>>
>> If the category is std::generic_category() then it also shows the
>> strerror description:
>
>
> I should probably extend this special case for the generic category to also apply to the system category when the OS is POSIX-based. For POSIX systems, the system error numbers are generic errno values.
>
>
>>
>> {"generic": 13 "Permission denied"}
>>
>> But I'd also like it to show the errno macro, but I'm not sure what's
>> the best way to show it.
>>
>> Does this seem OK?
>>
>> {"generic": 13 EACCES "Permission denied"}
>>
>> I think that's a bit too verbose.
>>
>> Would {"generic": EACCES} be better? You can always use ec.value() to
>> get the numeric value, and strerror to get the description if you want
>> those.
Here's what I plan to commit. It just uses {"generic": EACCES} for
known categories that use errno values, and {"foo": 99} for other
error categories.
It also supports std::error_condition (using the same printer and the
same output formats).
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commit f2de11d5f5758dfe90330b0efacbea9c7819df8e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Aug 16 17:41:50 2021
libstdc++: Add pretty printer for std::error_code and std::error_condition
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* python/libstdcxx/v6/printers.py (StdErrorCodePrinter): Define.
(build_libstdcxx_dictionary): Register printer for
std::error_code and std::error_condition.
* testsuite/libstdc++-prettyprinters/cxx11.cc: Test it.
diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index 550e0ecdd22..069c1bae183 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -18,7 +18,7 @@
import gdb
import itertools
import re
-import sys
+import sys, os, errno
### Python 2 + Python 3 compatibility code
@@ -1484,6 +1484,52 @@ class StdCmpCatPrinter:
name = names[int(self.val)]
return 'std::{}::{}'.format(self.typename, name)
+class StdErrorCatPrinter:
+ "Print an object derived from std::error_category"
+
+ def __init__ (self, typename, val):
+ self.val = val
+ self.typename = typename
+
+ def to_string (self):
+ gdb.set_convenience_variable('__cat', self.val)
+ name = gdb.parse_and_eval('$__cat->name()').string()
+ return 'error category = "{}"'.format(name)
+
+class StdErrorCodePrinter:
+ "Print a std::error_code or std::error_condition"
+
+ _errno_categories = None # List of categories that use errno values
+
+ def __init__ (self, typename, val):
+ self.val = val
+ self.typename = typename
+ # Do this only once ...
+ if StdErrorCodePrinter._errno_categories is None:
+ StdErrorCodePrinter._errno_categories = ['generic']
+ try:
+ import posix
+ StdErrorCodePrinter._errno_categories.append('system')
+ except ImportError:
+ pass
+
+ @staticmethod
+ def _category_name(cat):
+ "Call the virtual function that overrides std::error_category::name()"
+ gdb.set_convenience_variable('__cat', cat)
+ return gdb.parse_and_eval('$__cat->name()').string()
+
+ def to_string (self):
+ value = self.val['_M_value']
+ category = self._category_name(self.val['_M_cat'])
+ strval = str(value)
+ if value > 0 and category in StdErrorCodePrinter._errno_categories:
+ try:
+ strval = errno.errorcode[int(value)]
+ except:
+ pass
+ return '%s = {"%s": %s}' % (self.typename, category, strval)
+
# A "regular expression" printer which conforms to the
# "SubPrettyPrinter" protocol from gdb.printing.
class RxPrinter(object):
@@ -1886,6 +1932,8 @@ def build_libstdcxx_dictionary ():
libstdcxx_printer.add_version('std::__cxx11::', 'basic_string', StdStringPrinter)
libstdcxx_printer.add_container('std::', 'bitset', StdBitsetPrinter)
libstdcxx_printer.add_container('std::', 'deque', StdDequePrinter)
+ libstdcxx_printer.add_version('std::', 'error_code', StdErrorCodePrinter)
+ libstdcxx_printer.add_version('std::', 'error_condition', StdErrorCodePrinter)
libstdcxx_printer.add_container('std::', 'list', StdListPrinter)
libstdcxx_printer.add_container('std::__cxx11::', 'list', StdListPrinter)
libstdcxx_printer.add_container('std::', 'map', StdMapPrinter)
diff --git a/libstdc++-v3/testsuite/libstdc++-prettyprinters/cxx11.cc b/libstdc++-v3/testsuite/libstdc++-prettyprinters/cxx11.cc
index 05950513ab0..08f2c367f45 100644
--- a/libstdc++-v3/testsuite/libstdc++-prettyprinters/cxx11.cc
+++ b/libstdc++-v3/testsuite/libstdc++-prettyprinters/cxx11.cc
@@ -155,6 +155,25 @@ main()
// { dg-final { note-test tpl {std::tuple containing = {[1] = 6, [2] = 7}} } }
ExTuple &rtpl = tpl;
// { dg-final { note-test rtpl {std::tuple containing = {[1] = 6, [2] = 7}} } }
+
+ std::error_code e0;
+ // { dg-final { note-test e0 {std::error_code = {"system": 0}} } }
+ std::error_condition ec0;
+ // { dg-final { note-test ec0 {std::error_condition = {"generic": 0}} } }
+ std::error_code einval = std::make_error_code(std::errc::invalid_argument);
+ // { dg-final { note-test einval {std::error_code = {"generic": EINVAL}} } }
+ std::error_condition ecinval = std::make_error_condition(std::errc::invalid_argument);
+ // { dg-final { note-test ecinval {std::error_condition = {"generic": EINVAL}} } }
+
+ struct custom_cat : std::error_category {
+ const char* name() const noexcept { return "miaow"; }
+ std::string message(int) const { return ""; }
+ } cat;
+ std::error_code emiaow(42, cat);
+ // { dg-final { note-test emiaow {std::error_code = {"miaow": 42}} } }
+ std::error_condition ecmiaow(42, cat);
+ // { dg-final { note-test ecmiaow {std::error_condition = {"miaow": 42}} } }
+
placeholder(""); // Mark SPOT
use(efl);
use(fl);
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