Date: Wed, 20 May 2015 09:17:46 -0700 From: Adrian Chadd <adrian@freebsd.org> To: NGie Cooper <yaneurabeya@gmail.com> Cc: dave@sopwith.solgatos.com, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: Trying to use clang/head and XCC Message-ID: <CAJ-Vmoke6ZY=iF%2ByZgKQB-a5fzVGBo5QAZu6EJTLsm2o15wgxw@mail.gmail.com> In-Reply-To: <CAGHfRMAkT-iPX32RSdpq98shxGbujWH_HGpZ7oS=nZFrfEEtcg@mail.gmail.com> References: <CAMqLHRO%2BapPEpaKXgof9VN919xny2gRWY0_5F6eetgmdJ6Kv5Q@mail.gmail.com> <CAGHfRMAkT-iPX32RSdpq98shxGbujWH_HGpZ7oS=nZFrfEEtcg@mail.gmail.com>
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On 19 May 2015 at 17:50, NGie Cooper <yaneurabeya@gmail.com> wrote: > On Tue, May 19, 2015 at 1:35 PM, Dave Seifert > <davidalanseifert@gmail.com> wrote: >> sean typed: >>> No documentation of what CFLAGS are required to build and ignore warnings. >> >> Are you *sure* that ignoring those warnings is a good idea? > > The problem is that clang emits a *lot* of warnings with -Wall that > gcc doesn't, which causes failures if -Werror is enabled in the build > (annoying, but I've run into this at work...). Please see my earlier > reply about 10.0-RELEASE builds being broken on 11.0-CURRENT with > clang 3.6.0. > > Also, gcc emits different warnings because (IIRC) it analyzes code > that's been optimized whereas I believe clang does it beforehand > (please correct me if I'm wrong). I'm starting the process of finding/fixing issues that gcc-4.9.2 is finding/fixing on MIPS. It can only make things cleaner. I've also been bitten by the .. lack of clarity/sanity with how CFLAGS and such is populated. For MIPS, I discovered that: * there's stuff in kmod.*mk that sets -O and other flags, but it doesn't apply to normal kernel builds; and * the CFLAGS stuff in bsd.sys.mk is what's being paid attention to. Then we don't set the CPUTYPE stuff by default on MIPS, so I have to add CPUTYPE=mips32 or gcc-4.9.2 compiles mips1 code by default, which ends pretty hilariously in places. Fun times abound! -adrian
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