Re: [committed] libstdc++: Add GDB printers for <chrono> types

[Jonathan Wakely <jwakely@redhat.com>]

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On Wed, 27 Sept 2023 at 16:37, Tom Tromey <tromey@adacore.com> wrote:
>
> >>>>> Jonathan Wakely via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>
> Replying to a quite old email...
>
> I ran a Python linter on the libstdc++ pretty-printers.
>
> I have fixes for most of the issues that are worth fixing (I didn't
> bother with line lengths -- FWIW in gdb we just run 'black' and don't
> worry about these details),

I used autopep8 and committed the result as
e08559271b2d797f658579ac8610dbf5e58bcfd8 so the line lengths should be
OK now.

> but the patch I'm replying to had a problem
> that I didn't know how to fix:
>
> > +class StdChronoTimeZoneRulePrinter:
> [...]
> > +        if kind == 0: # DayOfMonth
> > +                start = '{} {}{}'.format(month, ordinal_day)
>
> flake8 points out that this call to format has three placeholders but
> only two arguments.

Oops, I think it was originally written like this:

'{} {}{}'.format(month, day, suffixes.get(day, 'th'))

but then I refactored it to:

ordinal_day = '{}{}'.format(day, suffixes.get(day, 'th'))
if kind == 0:  # DayOfMonth
            start = '{} {}{}'.format(month, ordinal_day)

So the fix is to just change the string to '{} {}' which I've pushed
as 1fab05a885a308c19cf42b72fd36805ddf27fdc8 now (also attached).

These printers are for implementation details internal to the library,
which are never exposed to users. I added them because they made it
much easier to debug the implementation when stepping through library
functions, but that means there are no tests for them.

Thanks for finding this!

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commit 1fab05a885a308c19cf42b72fd36805ddf27fdc8
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Sep 27 17:03:51 2023

    libstdc++: Fix format string in StdChronoTimeZoneRulePrinter
    
    libstdc++-v3/ChangeLog:
    
            * python/libstdcxx/v6/printers.py (StdChronoTimeZoneRulePrinter):
            Fix incorrect number of replacement fields.

diff --git a/libstdc++-v3/python/libstdcxx/v6/printers.py b/libstdc++-v3/python/libstdcxx/v6/printers.py
index c0056de2565..d60c8003a63 100644
--- a/libstdc++-v3/python/libstdcxx/v6/printers.py
+++ b/libstdc++-v3/python/libstdcxx/v6/printers.py
@@ -2215,7 +2215,7 @@ class StdChronoTimeZoneRulePrinter:
         day = on['day_of_month']
         ordinal_day = '{}{}'.format(day, suffixes.get(day, 'th'))
         if kind == 0:  # DayOfMonth
-            start = '{} {}{}'.format(month, ordinal_day)
+            start = '{} {}'.format(month, ordinal_day)
         else:
             weekday = weekdays[on['day_of_week']]
             if kind == 1:  # LastWeekDay