Avoid ubsan bug complaining about &p->field

I reckon it's quite OK to write &p->field in C when p might be NULL,
and lots of old C programmers probably agree with me.  However, ubsan
disagrees and so do some people I respect.  I suspect C++ influence is
to blame for the ubsan behaviour.  See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92634.  So far no one has
educated me as to why I'm wrong to claim that there isn't anything in
the C standard to say that p->field is always (*p).field.  Note 79
doesn't quite do that because it doesn't cover null pointers.  If
there was such an equivalence then you could claim &p->field has a
null pointer reference when p is NULL, even though no C compiler would
ever dereference p.

Anyway, to silence ubsan I'm going to apply the following though I
prefer to avoid casts when possible.  And I'm using (void *)
deliberately because this is C, not C++!

	* ldlang.c (lang_output_section_find_by_flags): Don't use &p->field
	when p might be NULL.
	* ldelf.c (output_rel_find, ldelf_place_orphan): Likewise.
	(insert_os_after, lang_insert_orphan, lookup_name): Likewise.
	(strip_excluded_output_sections, lang_clear_os_map): Likewise.
	(lang_check, lang_for_each_input_file): Likewise.
	(lang_reset_memory_regions, find_replacements_insert_point): Likewise.
	(find_rescan_insertion, lang_propagate_lma_regions): Likewise.
	(lang_record_phdrs): Likewise.
	* emultempl/alphaelf.em (alpha_after_open): Likewise.
	* emultempl/mmo.em (mmo_place_orphan): Likewise.
	* emultempl/pe.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
	* emultempl/pep.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
	* emultempl/ppc32elf.em (ppc_after_check_relocs): Likewise.
	* emultempl/spuelf.em (spu_before_allocation): Likewise.
	(embedded_spu_file): Likewise.

6 files changed, 7 insertions, 7 deletions

diff --git a/ld/emultempl/alphaelf.em b/ld/emultempl/alphaelf.em
index 4e7886f..db53d51 100644
--- a/ld/emultempl/alphaelf.em
+++ b/ld/emultempl/alphaelf.em
@@ -47,7 +47,7 @@ alpha_after_open (void)
       lang_output_section_statement_type *plt_os[2];
 
       num_plt = 0;
-      for (os = &lang_os_list.head->output_section_statement;
+      for (os = (void *) lang_os_list.head;
 	   os != NULL;
 	   os = os->next)
 	{
diff --git a/ld/emultempl/mmo.em b/ld/emultempl/mmo.em
index 85c5863..247d8a8 100644
--- a/ld/emultempl/mmo.em
+++ b/ld/emultempl/mmo.em
@@ -163,7 +163,7 @@ mmo_place_orphan (asection *s,
 
 	  /* We have to find the oss before this one, so we can use that as
 	     "after".  */
-	  for (lookup = &lang_os_list.head->output_section_statement;
+	  for (lookup = (void *) lang_os_list.head;
 	       lookup != NULL && lookup->next != before;
 	       lookup = lookup->next)
 	    ;
diff --git a/ld/emultempl/pe.em b/ld/emultempl/pe.em
index c4c6464..7e85ede 100644
--- a/ld/emultempl/pe.em
+++ b/ld/emultempl/pe.em
@@ -2151,7 +2151,7 @@ gld_${EMULATION_NAME}_place_orphan (asection *s,
 						       NULL);
 	  if (after == NULL)
 	    /* *ABS* is always the first output section statement.  */
-	    after = &lang_os_list.head->output_section_statement;
+	    after = (void *) lang_os_list.head;
 	}
 
       /* All sections in an executable must be aligned to a page boundary.
diff --git a/ld/emultempl/pep.em b/ld/emultempl/pep.em
index ec2d83f..f9f6a8e 100644
--- a/ld/emultempl/pep.em
+++ b/ld/emultempl/pep.em
@@ -1950,7 +1950,7 @@ gld_${EMULATION_NAME}_place_orphan (asection *s,
 						       NULL);
 	  if (after == NULL)
 	    /* *ABS* is always the first output section statement.  */
-	    after = &lang_os_list.head->output_section_statement;
+	    after = (void *) lang_os_list.head;
 	}
 
       /* All sections in an executable must be aligned to a page boundary.
diff --git a/ld/emultempl/ppc32elf.em b/ld/emultempl/ppc32elf.em
index 056068e..78a2eb1 100644
--- a/ld/emultempl/ppc32elf.em
+++ b/ld/emultempl/ppc32elf.em
@@ -79,7 +79,7 @@ ppc_after_check_relocs (void)
 
       num_got = 0;
       num_plt = 0;
-      for (os = &lang_os_list.head->output_section_statement;
+      for (os = (void *) lang_os_list.head;
 	   os != NULL;
 	   os = os->next)
 	{
diff --git a/ld/emultempl/spuelf.em b/ld/emultempl/spuelf.em
index 40a757a..96ac86f 100644
--- a/ld/emultempl/spuelf.em
+++ b/ld/emultempl/spuelf.em
@@ -290,7 +290,7 @@ spu_before_allocation (void)
 	    }
 
 	  /* Ensure alignment of overlay sections is sufficient.  */
-	  for (os = &lang_os_list.head->output_section_statement;
+	  for (os = (void *) lang_os_list.head;
 	       os != NULL;
 	       os = os->next)
 	    if (os->bfd_section != NULL
@@ -512,7 +512,7 @@ embedded_spu_file (lang_input_statement_type *entry, const char *flags)
     return FALSE;
   close (fd);
 
-  for (search = &input_file_chain.head->input_statement;
+  for (search = (void *) input_file_chain.head;
        search != NULL;
        search = search->next_real_file)
     if (search->filename != NULL)