Re: [Xen-devel] [PATCH v6 2/4] xen: introduce a C99 headers check

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 30 Mar 2017, Jan Beulich wrote:
> >>> On 30.03.17 at 00:18, <sstabellini@xxxxxxxxxx> wrote:
> > @@ -104,16 +105,22 @@ headers.chk: $(PUBLIC_ANSI_HEADERS) Makefile
> >     done >$@.new
> >     mv $@.new $@
> >  
> > +headers99.chk: $(PUBLIC_C99_HEADERS) Makefile
> > +   rm -f $@.new $@
> 
> Why also $@?
> 
> > +   $(foreach i, $(filter %.h,$^), $(CC) -x c -std=c99 -Wall -Werror \
> > +       -include stdint.h $($(i)-c99-prereq) -S -o /dev/null $(i) || \
> > +       exit 1; echo $(i) >> $@.new;)
> > +   mv $@.new $@
> > +
> >  headers++.chk: $(PUBLIC_HEADERS) Makefile
> > -   if $(CXX) -v >/dev/null 2>&1; then \
> > -       for i in $(filter %.h,$^); do \
> > -           echo '#include "'$$i'"' \
> > -           | $(CXX) -x c++ -std=gnu++98 -Wall -Werror -D__XEN_TOOLS__ \
> > -             -include stdint.h -include public/xen.h -S -o /dev/null - \
> > -           || exit 1; \
> > -           echo $$i; \
> > -       done ; \
> > -   fi >$@.new
> > +   if ! $(CXX) -v >/dev/null 2>&1; then \
> > +       exit 0;                          \
> > +   fi
> 
> How about
> 
>       $(CXX) -v >/dev/null 2>&1 || exit 0
> 
> avoiding the line continuations?
> 
> You can't, however, separate this from the rest (or else the
> following commands will be executed anyway).
> 
> > +   rm -f $@.new $@
> 
> This will then want moving ahead (without the $@).
> 
> > +   $(foreach i, $(filter %.h,$^), echo "#include "\"$(i)\"|       \
> > +       $(CXX) -x c++ -std=gnu++98 -Wall -Werror -D__XEN_TOOLS__   \
> > +       -include stdint.h $($(i)-cxx-prereq) -include public/xen.h \
> 
> I think the prereq(s) should come after public/xen.h (the presence
> of which I question anyway, as all headers should include it if there
> is a dependency).

I'll address all comments

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