Re: [patch+7.9] compile: Filter out -fpreprocessed

[Mark Wielaard <mjw@redhat.com>]

On Tue, 2015-02-03 at 19:59 +0100, Jan Kratochvil wrote:
> On Tue, 03 Feb 2015 19:50:40 +0100, Doug Evans wrote:
> > On Fri, Jan 16, 2015 at 2:42 PM, Jan Kratochvil
> > <jan.kratochvil@redhat.com> wrote:
> > > [...]
> > > It is wrong that gcc puts -fpreprocessed into DW_AT_producer - I may post a gcc
> > > patch for it.
> > 
> > I wasn't aware there are now rules for what can and cannot go in DW_AT_producer.
> > DW_AT_producer has gone from being informational to having a formal
> > spec (in the sense that something will break if, for example, a
> > particular option is mentioned).
> > Is this spec written down somewhere? [At least guidelines for what
> > things may lead to breakage?]
> 
> No. Do you have a suggestion where to put it? Should it be only a GNU
> extension or should it be even DWARF-standardized?

The gcc documentation describes it:
https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html

-grecord-gcc-switches
        This switch causes the command-line options used to invoke the
        compiler that may affect code generation to be appended to the
        DW_AT_producer attribute in DWARF debugging information. The
        options are concatenated with spaces separating them from each
        other and from the compiler version. See also
        -frecord-gcc-switches for another way of storing compiler
        options into the object file. This is the default.

-gno-record-gcc-switches
        Disallow appending command-line options to the DW_AT_producer
        attribute in DWARF debugging information.

So Jan is right that gcc adding -fpreprocessed, which doesn't affect
code generation, but is a preprocessor option, shouldn't be there.

Cheers,

Mark