Re: [gentoo-dev] [PATCH 1/5] toolchain-funcs.eclass: Add functions for detection of PIE / SSP in way compatible with GCC >=6.

[Michał Górny]

On czw, 2017-06-15 at 03:09 -0500, Matthias Maier wrote:
> > > +# @FUNCTION: tc-enables-pie
> > > +# @RETURN: Truth if the current compiler generates position-independent code (PIC) which can be linked into executables
> > > +# @DESCRIPTION:
> > > +# Return truth if the current compiler generates position-independent code (PIC)
> > > +# which can be linked into executables.
> > > +tc-enables-pie() {
> > > +	$($(tc-getCC) ${CPPFLAGS} ${CFLAGS} -E -P - <<-EOF 2> /dev/null
> > > +		#if defined(__PIE__)
> > > +		true
> > > +		#else
> > > +		false
> > > +		#endif
> > > +		EOF
> > > +	)
> >
> > Looks quite horrible. Why can't you just compare the output against
> > a value instead of randomly executing it?
>
> Because we have to execute the compiler anyway and this is the quickest
> way of getting the answer we need. Further, piping an unfiltered output
> (e.g. -E -dM -x c) through grep is by no means prettier.
>

That's not what I mean. What I mean is that you are executing
the filtered output, i.e. calling whatever gets spilt on stdout as shell
script.

-- 
Best regards,
Michał Górny