Set dynamic_undefined_weak to zero for static PIEs

[Alan Modra <amodra at gmail dot com>]

I believe we should be warning if ld is given both --no-dynamic-linker
and -z dynamic-undefined-weak.  The two options are contradictory, the
first says an executable has no dynamic interpreter to resolve dynamic
symbols, while the second is asking for dynamic symbols to be emitted.
(And even if a static PIE's relocation code, which is needed to
process R_*_RELATIVE relocs, could process symbols, there are no
DT_NEEDED dynamic objects to define such symbols.)

I also think that dynamic_undefined_weak is the right flag to control
whether undefined weaks are made dynamic, whether in static PIEs or
anywhere else.  So force it to 0 for static PIEs, fixing PR 22269 for
powerpc and any other target where the backend usually defaults to
undefined weaks being made dynamic.

This patch introduces regressions.  I'd normally not do that, but
these are all in very recently added test cases, or expose bugs in the
x86 backend.  The test cases were added after I'd made it known that
this patch or one like it was imminent.

	PR 22269
	* emultempl/elf32.em (after_parse): Warn on --no-dynamic-linker
	-z dynamic-undefined-weak combination.  Set dynamic_undefined_weak
	to zero when nointerp.

diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index e6cf968..8737376 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -120,6 +120,13 @@ gld${EMULATION_NAME}_after_parse (void)
   if (bfd_link_pie (&link_info))
     link_info.flags_1 |= (bfd_vma) DF_1_PIE;
 
+  if (bfd_link_executable (&link_info)
+      && link_info.nointerp)
+    {
+      if (link_info.dynamic_undefined_weak > 0)
+	einfo (_("%P: warning: -z dynamic-undefined-weak ignored\n"));
+      link_info.dynamic_undefined_weak = 0;
+    }
   after_parse_default ();
 }
 

-- 
Alan Modra
Australia Development Lab, IBM