Re: [PATCH] Makefile: detect compiler and enable more warnings in DEVELOPER=1

From: Jeff King <peff@peff.net>
Date: Mar 20, 2018, 05:32 UTC
Message-ID: <20180320053220.GB15813@sigill.intra.peff.net>
In-Reply-To: <CACsJy8BOCpHiMxJ0K=_-WPf9b4yh0W0i3m9sAo5-Sk5fY9x1+A@mail.gmail.com>

On Sun, Mar 18, 2018 at 04:55:25PM +0100, Duy Nguyen wrote:

Show 8 quoted lines

> On Sun, Mar 18, 2018 at 9:18 AM, Nguyễn Thái Ngọc Duy <pclouds@gmail.com> wrote:
> > +ifneq ($(or $(filter gcc6,$(COMPILER_FEATURES)),$(filter clang4,$(COMPILER_FEATURES))),)
> > +CFLAGS += -Wextra
> 
> Another thing we can add here is -Og instead of standard -O2 (or -O0
> in my build), which is supported since gcc 4.8. clang seems to support
> it too (mapped to -O1 at least for clang5) but I don't know what
> version added that flag.

I don't know, that feels kind of weird to me. I thought DEVELOPER was supposed to mean "ratchet up the linting, I want to know if I've broken something".

But tweaking -O is about "I am in an edit-compile-debug cycle". Sometimes you are and sometimes you aren't, but you'd presumably want to have extra warnings regardless (especially because some warnings only trigger under particular optimization settings).

Personally, I default to -O0, but then crank up to -O2 for performance testing or for my daily-driver builds. But I _always_ have as many warnings enabled as possible[1].

-Peff

[1] I do have some pretty horrific magic to turn on -Werror when I'm
    visiting a "historical" commit, such as during a bisect.