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List:       openjdk-2d-dev
Subject:    Re: [OpenJDK 2D-Dev] [REGRESSION?] Build warnings at jdhuff.c with GCC 6
From:       Erik Joelsson <erik.joelsson () oracle ! com>
Date:       2016-08-26 7:23:43
Message-ID: 3fa82b5f-975b-4dca-e1d3-5b8b31e6d011 () oracle ! com
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On 2016-08-25 23:28, Kim Barrett wrote:
> > On Aug 24, 2016, at 5:48 AM, Erik Joelsson <erik.joelsson@oracle.com> wrote:
> > 
> > Hello,
> > 
> > 
> > On 2016-08-23 18:12, Phil Race wrote:
> > > On 08/23/2016 08:47 AM, Erik Joelsson wrote:
> > > > Hello,
> > > > 
> > > > I do agree that maintaining the list of disabled warnings will be
> > > > impossible unless we have a structured way of tracking for which
> > > > compiler versions we disable what. Ideally we should be able to easily
> > > > add conditions for when certain warnings should be disabled. We are
> > > > unfortunately lacking that today and at least I don't have the
> > > > bandwidth to fix that anytime soon.
> > > > 
> > > > The official compilers are only really official for Oracle. The
> > > > OpenJDK can (and should) be buildable with a much wider range of
> > > > compiler versions.
> > > I agree there. This is fortunately not an "unbuildable" situation.
> > > The only other option I can think of which may or may not be palatable
> > > is to explicitly
> > > check the compiler version and add that disabled warning only for that
> > > exact compiler version.
> > > There'd still be some maintenance as that compiler version became either
> > > official .. or obsolete ..
> > > 
> > > Is there precedent (or any kind of support) for that ?
> > What I had in mind was a structured way of adding conditionals for some kind of \
> > ranges of compiler versions, or at least something like 6.*, or "greater than \
> > 4.9.3". It's pretty simple today to check for exact compiler versions but then we \
> > end up with a lot of changes when minor versions are bumped. I don't think that \
> > would be worth it. 
> > In this particular case is shift-negative-value a new warning in GCC 6? If that's \
> > the case it doesn't actually hurt adding it since GCC is nice enough to not \
> > complain about unknown warning tags.
> Not reviewing, but this caught my eye.
> 
> The feature of not complaining about unknown -Wno-xxx warning options is only since \
> gcc4.4. Some folks (like SAP) are still using versions that are older than that.
That is true, so configure checks if gcc complains about unknown 
warnings. If not, we automatically do not add the -Wno-* arguments.

/Erik
> > If we do, just make sure to specify in a comment that it's specific to GCC \
> > version 6+.


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