Properly controlling CFLAGS/CXXFLAGS

[Uwe Doering]

Garrett Cooper wrote:
>> [...]
> Interesting. No wonder I didn't have it in my Gentoo /etc/make.conf. It 
> appears (from what I see) that maybe -fno-strict-aliasing has been 
> enabled by default (at least it doesn't show up in the GCC 4.1.1 manpage 
> on FC5).

It's documented in GCC's info page.  There, you may want to search for 
'-fstrict-aliasing' instead of '-fno-strict-aliasing'.  The 'no-' prefix 
is generic and can be used to switch off flags that are on by default or 
have been set to on earlier in the command line.

With '-O2' and better, '-fstrict-aliasing' is the default in newer 
versions of GCC, AFAIK, but people tend to switch it off because it 
apparently breaks too many software packages.  Or at least those whose 
code base dates back to times where '-fno-strict-aliasing' was the 
default and people got away with certain nasty coding hacks that no 
longer work with '-fstrict-aliasing'.

    Uwe
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