Jon Turney wrote:
> On 02/08/2022 13:17, Christian Franke wrote:
>> In long standing cygwin installations, many no longer needed 
>> automatically installed packages (e.g. libicuNN) accumulate. This 
>> patch adds a new view which is possibly helpful to cleanup packages 
>> manually.
>>
>> Some possible later enhancements:
>> - automatically refresh this view (a few seconds) after the user 
>> changed a package status as this may add or remove entries.
>> - add a keyboard shortcut (^U) to the list view for "Uninstall this 
>> package and then select next package"
>>
>
> Thanks.  This looks good.
>
> I think perhaps a better approach would be a view showing all packages 
> which aren't user_picked, or a dependency of a user_picked package.

This would drop the ability to easily clean up user_picked packages 
without later conflicts. The attached new patch splits this into two 
views "Removable" (not "Uninstallable" due to possible ambiguity with 
"cannot be installed") and "Unneeded" (or "Stale" ?).


>
> (If I've read the code correctly your implementation has the weakness 
> that if e.g. appA -> libbB -> libC, which is then changed to appA -> 
> libD -> libE, it will only show libC as unneeded, then libB on the 
> next run?)

I'm not sure for this case. It may be correct again after the view is 
refreshed during the same run. In general, this ad-hoc algorithm does 
not handle all corner cases. It should be sufficient if installation 
cleanup is done in a separate run.


>
>
>> +// Scan installed or desired packages and collect the names of packages
>> +// which provide the dependencies of other packages or are member of
>> +// category "Base".
>> +static void FindNeededPackages (const packagedb & db, 
>> std::set<std::string> & needed)
>> +{
>> +  std::map<std::string, std::string> providedBy;
>> +  for (const auto & p : db.packages)
>> +    {
>> +      const packagemeta & pkg = *p.second;
>> +      if (!pkg.isBinary ())
>> +        continue;
>> +      if (!(pkg.desired && (pkg.installed || pkg.picked ())))
>> +        continue;
>
> This seems redundant.  Why can't this be just !pkg.desired?

Yes, fixed. I originally wanted to handle the "install source package 
without the binary" case here. During development of "Ctrl+I/R/U" patch, 
I learned that this could not happen.


> This should also update the tooltip for the view dropdown 
> (IDS_VIEWBUTTON_TOOLTIP) to describe the new view.
>

Done.

Open issue: An easy way to refresh the views after Uninstall requests 
(Ctrl+L ?).