Re: [PATCH 0/2] -Wuninitialized

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Mar 20, 2018, 14:46 UTC
Message-ID: <nycvar.QRO.7.76.6.1803201514490.55@ZVAVAG-6OXH6DA.rhebcr.pbec.zvpebfbsg.pbz>
In-Reply-To: <8f6d8e2e-aba4-128c-f17c-6c1b9c12436c@ramsayjones.plus.com>

Hi Ramsay,

On Mon, 19 Mar 2018, Ramsay Jones wrote:

Show 9 quoted lines

> This series removes all 'self-initialised' variables (ie. <type> var =
> var;).  This construct has been used to silence gcc
> '-W[maybe-]uninitialized' warnings in the past [1]. Unfortunately, this
> construct causes warnings to be issued by MSVC [2], along with clang
> static analysis complaining about an 'Assigned value is garbage or
> undefined'. The number of these constructs has dropped over the years
> (eg. see [3] and [4]), so there are currently only 6 remaining in the
> current codebase. As demonstrated below, 5 of these no longer cause gcc
> to issue warnings.

Thank you so much for working on this!

In Git for Windows, to work around the MSVC issues you mention, I have this ugly work-around (essentially, it has a FAKE_INIT() macro that either performs that GCC workaround or initializes the variable to NULL/0):

	https://github.com/git-for-windows/git/commit/474155f32a

FWIW I just tested your patches with Visual Studio 2017 and there are no C4700 warnings (the equivalent of GCC's "may be uninitialized" warning) [*1*].

You can find the patches (your patches rebased onto Git for Windows' master, plus a patch adding the project files for Visual Studio) here:

https://github.com/git-for-windows/git/compare/master...dscho:msvc-uninitialized-warning-test

So here is my ACK, in case you want it ;-)

Ciao, Dscho

Footnote *1*: there actually was one, but in a Windows-only patch. That's what that last (fixup!) patch on my branch is all about.