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Re: [PATCH] Add a couple of dialect and warning options regarding Objective-C instance variable scope

Since there obviously is no interest in this patch I'm simply going to attach it to the ticket mentioned below (Bug 56044) in case someone decides to look into it in the future. If anyone should want to comment on this please do so at the bug tracker since I probably won't be following this list.


On 06/24/2013 03:04 PM, Dimitris Papavasiliou wrote:
Ping! Would anybody care to comment on this?

On 06/10/2013 12:44 AM, Dimitris Papavasiliou wrote:

First, let me say that I have consciously broken most of the rules
mentioned about patch submission at but I have done so in
order to spare myself from wasting time to provide a proper patch in
case the implemented functionality is not deemed worthy of approval and
adoption into GCC. If any of the implemented switches prove to be
welcome I'll be more than happy to split them into separate patches, add
test-cases and add ChangLog entries as needed.

Two of these switches are related to a feature request I submitted a
while ago, Bug 56044
( I won't reproduce
the entire argument here since it is available in the feature request.
The relevant functionality in the patch comes in the form of two

-Wshadow-ivars which controls the "local declaration of ‘somevar’ hides
instance variable" warning which curiously is enabled by default instead
of being controlled at least by -Wshadow. The patch changes it so that
this warning can be enabled and disabled specifically through
-Wshadow-ivars as well as with all other shadowing-related warnings
through -Wshadow.

The reason for the extra switch is that, while searching through the
Internet for a solution to this problem I have found out that other
people are inconvenienced by this particular warning as well so it might
be useful to be able to turn it off while keeping all the other
shadowing-related warnings enabled.

-flocal-ivars which when true, as it is by default, treats instance
variables as having local scope. If false (-fno-local-ivars) instance
variables must always be referred to as self->ivarname and references of
ivarname resolve to the local or global scope as usual.

I've also taken the opportunity of adding another switch unrelated to
the above but related to instance variables:

-fivar-visibility which can be set to either private, protected (the
default), public and package. This sets the default instance variable
visibility which normally is implicitly protected. My use-case for it is
basically to be able to set it to public and thus effectively disable
this visibility mechanism altogether which I find no use for and
therefore have to circumvent. I'm not sure if anyone else feels the same
way towards this but I figured it was worth a try.

I'm attaching a preliminary patch against the current revision in case
anyone wants to have a look. The changes are very small and any blatant
mistakes should be immediately obvious. I have to admit to having
virtually no knowledge of the internals of GCC but I have tried to keep
in line with formatting guidelines and general style as well as looking
up the particulars of the way options are handled in the available
documentation to avoid blind copy-pasting. I have also tried to test the
functionality both in my own (relatively large, or at least not too
small) project and with small test programs and everything works as
expected. Finallly, I tried running the tests too but these fail to
complete both in the patched and unpatched version, possibly due to the
way I've configured GCC.


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