Re: [changes.html] Document -fdiagnostics-color= default changes

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Nov 14, 2014 at 01:14:02PM +0100, Manuel López-Ibáñez wrote:
> >
> >  <h3 id="c-family">C family</h3>
> >    <ul>
> > +    <li>The <code>-fdiagnostics-color=</code> option default is now
> > +    configurable at GCC configury time using
> > +    <code>--with-diagnostics-color=</code>, can default to
> > +    <code>auto</code> - the new default unless configured otherwise,
> > +    where diagnostics is colorized by default when emitted to terminal,
> > +    <code>never</code>, <code>always</code> or <code>auto-if-env</code>,
> > +    which is the default of GCC 4.9 - <code>auto</code> if non-empty
> > +    <code>GCC_COLORS</code> is in the environment, <code>never</code>
> > +    otherwise.  Note, as before, having empty <code>GCC_COLORS</code>
> > +    variable in the environment will always turn the coloring off, no
> > +    matter what the default is or what command line options are used.</li>
> 
> This not only affects 'C family' but also Fortran now, so perhaps it
> should go in the Caveats section at the top or on a "Building GCC"

Well, it doesn't look like something for Caveats section IMHO, it is an
extension of the previous behavior.  The reason I put it into the C family
part is that that is where it was documented for 4.9, and for Fortran IMHO
gcc-5/changes.html just should document that now it supports diagnostics
colors like the C family of frontends.

> section. Apart from that, do you think the following is a bit clearer?
> 
> <li>The default setting of the <code>-fdiagnostics-color=</code> option is now
> configurable <a href
> ="https://gcc.gnu.org/install/configure.html";>when building GCC</a>
> using configuration option <code>--with-diagnostics-color=</code>. The
> possible values are:
> <code>never</code>, <code>always</code>, <code>auto</code> and
> <code>auto-if-env</code>.
> The new default <code>auto</code> means to use color only when the
> standard error is a terminal.
> The default in GCC 4.9 was <code>auto-if-env</code>, which defaults to
> <code>auto</code> if there is a non-empty <code>GCC_COLORS</code>
> environment
> variable, and <code>never</code> otherwise. As in GCC 4.9, an empty
> <code>GCC_COLORS</code> variable in the environment will always
> disable colors, no
> matter what the default is or what command line options are used.</li>

Indeed, it does.  So feel free to turn that into patch form.

	Jakub