init_priority

[Phil Edwards]

Well, I've found a couple things.

On Wed, Dec 20, 2000 at 05:57:29PM -0500, Phil Edwards wrote:
> 
> Here's a piece of example code.  (Compile all these example with recent
> g++ and -finit-priority.)  This only does objects within a single file,
          ^^^^^^^^^^^^^^^
As it turns out, this is on by default; both positive and negative forms
are silently ignored.  I feel we should warn about useless options.


> BUG:  When the manual says that "this requires GNU ld 2.10 or later,"
> they aren't joking.  When using the native Sun ld on the above code,
> no warnings were printed, and the objects /never/ were initialized.
> The executable printed "Blah." and exited.  Ouch!
> 
> We should warn in this case.  I'll see if I can do up a patch.

This is going to be interesting.  I don't think we have any method of
programmatically answering either of these questions:

    1)  Are we using an ELF system?
    2)  Are we using (configured with/for) GNU ld?

We have a configure variable for (2), but it hasn't yet been turned into
an AC_DEFINE yet.

If I'm missing something obvious, someone please tell me.  What I have
in mind is something like this patch (the #if conditionals are just
placeholders):


Index: decl2.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/decl2.c,v
retrieving revision 1.416
diff -u -3 -p -r1.416 decl2.c
--- decl2.c	2000/12/07 07:56:43	1.416
+++ decl2.c	2000/12/21 20:29:28
@@ -611,6 +611,11 @@ lang_decode_option (argc, argv)
 	  flag_alt_external_templates = 1;
           cp_deprecated ("-falt-external-templates");
 	}
+      else if (!strcmp (p, "init-priority")
+               || !strcmp (p, "init-priority"))
+        {
+          warning ("-finit-priority is unneeded (it is on by default)");
+        }
       else if (! strcmp (p, "no-alt-external-templates"))
 	flag_alt_external_templates = 0;
       else if (!strcmp (p, "repo"))
Index: tree.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/tree.c,v
retrieving revision 1.226
diff -u -3 -p -r1.226 tree.c
--- tree.c	2000/12/21 17:50:07	1.226
+++ tree.c	2000/12/21 20:29:28
@@ -2309,6 +2309,11 @@ cp_valid_lang_attribute (attr_name, attr
 	  warning 
 	    ("requested init_priority is reserved for internal use");
 	}
+#if ELF && !GNU_LD
+      /* Ctor/dtor reordering under ELF without GNU ld is probably
+         going to do very bad things. */
+      warning ("using init_priority on this system without GNU ld may cause unexpected results");
+#endif
 
       DECL_INIT_PRIORITY (decl) = pri;
       return 1;