[PATCH util-macros 1/2] Don't disable strict aliasing (-fno-strict-aliasing) globally

[Gaetan Nadon]

On Mon, 2010-11-01 at 12:17 -0700, Jeremy Huddleston wrote:

> 1) It is *NOT* a warning flag.  Using CWARNFLAGS should *only* enable
> warnings, not change the resulting assembly.
> 
> 2) It was never intended to be in all of the modules.  It landed there
> by accident when the code was copy/pasted from one configure.ac to
> another and then into util-macros.
> 
> 3) Performance gains are not in consideration here.
> 

I totally agree, but it does not justify simply removing the offending
flag as if it had never existed. It does have an impact on the binaries,
some modules need it, other don't, but we don't know which ones for
sure. That's my understanding, I could be wrong.

I have made a concrete proposal:


     1. It preserves backward compatibility so previous versions are
        unaffected when configured with the latest util-macros
     2. It provides a low risk approach which I believe will be
        supported by reviewers.
     3. It gets you where you want to be, but perhaps not in "one go"

I'd like to hear how this proposal will not provide the end result you
are looking for. There must be a misunderstand somewhere, so we have to
keep working hard to find it.


===============================================================================
This is what I had found at the time:


Modules which had CWARNFLAGS added a year ago *and* did not have -fno-strict-aliasing option prior to that:


        font=	"util"
        app=	"appres bdftopcf beforelight bitmap editres fonttosfnt fslsfonts fstobdf iceauth \
        	ico listres luit mkcomposecache mkfontscale oclock rendercheck rgb rstart  sessreg setxkbmap \
        	showfont smproxy viewres x11perf xauth xbacklight xbiff xcalc xclipboard xclock xcmsdb xconsole \
        	xcursorgen xdbedizzy xdm xdpyinfo xdriinfo xedit xev xeyes xf86dga xfd xfontsel xfs xfsinfo \
        	xgamma xgc xhost xinit xkbcomp xkbevd xkbprint xkbutils xkill xload xlogo xlsatoms xlsclients \
        	xlsfonts xmag  xman xmessage xmh xmodmap xmore xprop xrandr xrdb xrefresh xscope xset xsetmode \
        	xsetpointer xsetroot xsm xstdcmap xvidtune xvinfo xwd xwininfo xwud"
        lib="	libAppleWM 	libdmx 		libfontenc 	libFS 		libpciaccess 	libWindowsWM \
        	libXaw 		libXcomposite 	libXcursor 	libXdamage 	libXdmcp 	libXext \
        	libXfixes 	libXi 		libXinerama 	libxkbfile 	libXmu 		libXrandr \
        	libXrender 	libXScrnSaver 	libXt 		libXtst 	libXv 		libXvMC \
        	libXxf86dga"
        driver="xf86-input-acecad 	xf86-input-aiptek 	xf86-input-evdev \
        	xf86-input-joystick 	xf86-input-keyboard 	xf86-input-mouse \
        	xf86-input-wacom 	xf86-video-cirrus 	xf86-video-mach64 \
        	xf86-video-qxl 		xf86-video-siliconmotion"



Modules which never had -fno-strict-aliasing nor any warning flags of any kind and still don't today:


        app="mkfontdir scripts twm xditview xinput"
        lib="libXxf86vm"
        driver="xf86-input-synaptics	xf86-input-vmmouse \
        	xf86-input-void		xf86-video-apm		xf86-video-ark \
        	xf86-video-ast		xf86-video-ati		xf86-video-chips \
        	xf86-video-dummy	xf86-video-fbdev\
        	xf86-video-glint 	xf86-video-i128 	xf86-video-i740	\
        	xf86-video-mga		xf86-video-neomagic	xf86-video-newport \
        	xf86-video-nv		xf86-video-r128 \
        	xf86-video-rendition	xf86-video-s3		xf86-video-s3virge \
        	xf86-video-savage	xf86-video-sis		xf86-video-sisusb \
        	xf86-video-suncg14	xf86-video-suncg3	xf86-video-suncg6 \
        	xf86-video-sunffb 	xf86-video-sunleo	xf86-video-suntcx \
        	xf86-video-tdfx 	xf86-video-tga		xf86-video-trident \
        	xf86-video-tseng	xf86-video-v4l		xf86-video-vesa \
        	xf86-video-vmware	xf86-video-voodoo	xf86-video-wsfb \
        	xf86-video-xgi		xf86-video-xgixp "


Modules which had -fno-strict-aliasing for a long time (prior to CWARNFLAGS era)


        lib="libICE libSM libX11 libXau libXfont libXft libXpm libXres"
        driver="xf86-video-intel xf86-video-geode xf86-video-radeonhd"
        xserver

========================================================================

Gaetan
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