[patch] Fix crash on reading gcc HEAD Fortran module

[patch] Fix crash on reading gcc HEAD Fortran module

[Jan Kratochvil]

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Hi,

with the current gcc snapshot this testcase
MODULE m
  integer :: varx
END MODULE m
USE m, a=>varx
end

crashes gdb HEAD on `break 2' with:
dwarf2read.c:2766: internal-error: process_die: Assertion `die->child == NULL' failed.
A problem internal to GDB has been detected,

While it still cannot reach the imported variables it at least no longer
crashes now.  Notified by Tobias Burnus.


Regards,
Jan

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2008-09-01  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Stay compatible after the GCC PR fortran/29635 fix.
	* dwarf2read.c (process_die <DW_TAG_imported_module>): Accept (ignored)
	child DIEs.  Only COMPLAINT for non-Fortran languages.

--- gdb/dwarf2read.c	29 Aug 2008 17:06:05 -0000	1.278
+++ gdb/dwarf2read.c	1 Sep 2008 12:56:19 -0000
@@ -2763,7 +2763,10 @@ process_die (struct die_info *die, struc
 	 Fortran case, so we'll have to replace this gdb_assert if
 	 Fortran compilers start generating that info.  */
       processing_has_namespace_info = 1;
-      gdb_assert (die->child == NULL);
+      if (cu->language != language_fortran && die->child == NULL)
+	complaint (&symfile_complaints,
+		   _("%s at offset %d has unexpected children"),
+		   dwarf_tag_name (die->tag), die->offset);
       break;
     default:
       new_symbol (die, NULL, cu);

Re: [patch] Fix crash on reading gcc HEAD Fortran module

[Daniel Jacobowitz]

On Mon, Sep 01, 2008 at 03:02:12PM +0200, Jan Kratochvil wrote:
> 2008-09-01  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	Stay compatible after the GCC PR fortran/29635 fix.
> 	* dwarf2read.c (process_die <DW_TAG_imported_module>): Accept (ignored)
> 	child DIEs.  Only COMPLAINT for non-Fortran languages.

This patch is mostly OK; please complain about children in
DW_TAG_imported_declaration even in Fortran (see the comment above
your change).

-- 
Daniel Jacobowitz
CodeSourcery

Re: [patch] Fix crash on reading gcc HEAD Fortran module

[Jan Kratochvil]

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On Mon, 01 Sep 2008 17:29:56 +0200, Daniel Jacobowitz wrote:
> please complain about children in DW_TAG_imported_declaration even in
> Fortran (see the comment above your change).

Originally I expected these complaints are just for detected DWARF violations:
	_("Offset %d out of bounds for DW_AT_ranges attribute"),
But they are produced even just for unsupported DWARF features:
	complaint (&symfile_complaints, _("unsupported tag: '%s'"),

Therefore it should always complain to any such DW_TAG_imported_* tag as they
are always at least unsupported.  (And it does not matter if some of their
forms with or without children are invalid for DWARF or not.)

[ approval requested ]


Thanks,
Jan

[-- Attachment #2: gdb-cvs-module-import.patch --]
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2008-09-01  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Stay compatible after the GCC PR fortran/29635 fix.
	* dwarf2read.c (process_die <DW_TAG_imported_module>)
	(process_die <DW_TAG_imported_module>): Do not assert anything about
	these unsupported tags.

--- ./gdb/dwarf2read.c	29 Aug 2008 17:06:05 -0000	1.278
+++ ./gdb/dwarf2read.c	1 Sep 2008 16:35:17 -0000
@@ -2760,10 +2760,10 @@ process_die (struct die_info *die, struc
 	 information contained in these.  DW_TAG_imported_declaration
 	 dies shouldn't have children; DW_TAG_imported_module dies
 	 shouldn't in the C++ case, but conceivably could in the
-	 Fortran case, so we'll have to replace this gdb_assert if
-	 Fortran compilers start generating that info.  */
+	 Fortran case.  */
       processing_has_namespace_info = 1;
-      gdb_assert (die->child == NULL);
+      complaint (&symfile_complaints, _("unsupported tag: '%s'"),
+		 dwarf_tag_name (die->tag));
       break;
     default:
       new_symbol (die, NULL, cu);

Re: [patch] Fix crash on reading gcc HEAD Fortran module

[Daniel Jacobowitz]

On Mon, Sep 01, 2008 at 06:51:07PM +0200, Jan Kratochvil wrote:
> Therefore it should always complain to any such DW_TAG_imported_* tag as they
> are always at least unsupported.  (And it does not matter if some of their
> forms with or without children are invalid for DWARF or not.)

Good point.  This is OK.

-- 
Daniel Jacobowitz
CodeSourcery