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Re: [Patch][GCC] Document and fix -r (partial linking)


On Mittwoch, 1. August 2018 18:32:30 CEST Joseph Myers wrote:
> On Wed, 1 Aug 2018, Allan Sandfeld Jensen wrote:
> > gcc/
> > 
> >     * gcc.c: Correct default specs for -r
> 
> I don't follow why your changes (which would need describing for each
> individual spec changed) are corrections.
> 
> >  /* config.h can define LIB_SPEC to override the default libraries.  */
> >  #ifndef LIB_SPEC
> > 
> > -#define LIB_SPEC "%{!shared:%{g*:-lg}
> > %{!p:%{!pg:-lc}}%{p:-lc_p}%{pg:-lc_p}}" +#define LIB_SPEC
> > "%{!shared|!r:%{g*:-lg} %{!p:%{!pg:-lc}}%{p:-lc_p}%{pg:-lc_p}}"> 
> >  #endif
> 
> '!' binds more closely than '|' in specs.  That is, !shared|!r means the
> following specs are used unless both -shared and -r are specified, which
> seems nonsensical to me.  I'd expect something more like "shared|r:;" to
> expand to nothing if either -shared or -r is passed and to what follows if
> neither is passed.
> 
> And that ignores that this LIB_SPEC value in gcc.c is largely irrelevant,
> as it's generally overridden by targets - and normally for targets using
> ELF shared libraries, for example, -lc *does* have to be used when linking
> with -shared.
> 
> I think you're changing the wrong place for this.  If you want -r to be
> usable with GCC without using -nostdlib (which is an interesting
> question), you actually need to change LINK_COMMAND_SPEC (also sometimes
> overridden for targets) to handle -r more like -nostdlib -nostartfiles.
> 
Ok, thanks for the information, I will investigate that. 

> > -#define LINK_PIE_SPEC "%{static|shared|r:;" PIE_SPEC ":" LD_PIE_SPEC "} "
> > +#define LINK_PIE_SPEC "%{static|shared|r|ar:;" PIE_SPEC ":" LD_PIE_SPEC
> > "} "
> What's this "-ar" option you're handling here?

Dead code from a previous more ambitious version of the patch. I will remove.

`Allan




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