[Patch, Fortran] PR 41755 - Fix segfault for invalid EQUIVALENCE

[Tobias Burnus <burnus@net-b.de>]

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I think the patch is obvious. As it works with 4.2, it is a regression.

The FIXME change is unrelated and small - and obviously only for the trunk.

Build and regtested on x86-64-linux.
OK for the trunk and 4.4? - I can also commit it for 4.3, if deemed useful.

Tobias

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2009-10-19  Tobias Burnus  <burnus@net-b.de>

	PR fortran/41755
	* symbol.c (gfc_undo_symbols): Add NULL check.
2009-10-19  Tobias Burnus  <burnus@net-b.de>

	PR fortran/41755
	* gfortran.dg/equiv_8.f90: New test.
	* gfortran.dg/class_allocate_1.f03: Remove obsolete FIXME.

Index: gcc/fortran/symbol.c
===================================================================
--- gcc/fortran/symbol.c	(revision 152976)
+++ gcc/fortran/symbol.c	(working copy)
@@ -2741,7 +2741,7 @@ gfc_undo_symbols (void)
       if (p->gfc_new)
 	{
 	  /* Symbol was new.  */
-	  if (p->attr.in_common && p->common_block->head)
+	  if (p->attr.in_common && p->common_block && p->common_block->head)
 	    {
 	      /* If the symbol was added to any common block, it
 		 needs to be removed to stop the resolver looking
Index: gcc/testsuite/gfortran.dg/equiv_8.f90
===================================================================
--- gcc/testsuite/gfortran.dg/equiv_8.f90	(revision 0)
+++ gcc/testsuite/gfortran.dg/equiv_8.f90	(revision 0)
@@ -0,0 +1,7 @@
+! { dg-do compile }
+!
+! PR fortran/41755
+!
+      common /uno/ aa
+      equivalence (aa,aaaaa)   (bb,cc) ! { dg-error "Syntax error in EQUIVALENCE" }
+      end
Index: gcc/testsuite/gfortran.dg/class_allocate_1.f03
===================================================================
--- gcc/testsuite/gfortran.dg/class_allocate_1.f03	(revision 152976)
+++ gcc/testsuite/gfortran.dg/class_allocate_1.f03	(working copy)
@@ -68,8 +68,7 @@
 
  i = 0
  allocate(t2 :: cp2)
-! FIXME: Not yet supported: source=<class>
-! allocate(cp, source = cp2)
+ allocate(cp, source = cp2)
  allocate(t2 :: cp3)
  allocate(cp, source=cp3)
  select type (cp)