Fix ICE for maps with zero components.

2016-09-30  Fritz Reese  <fritzoreese@gmail.com>

Fix ICE for maps with zero components.

	PR fortran/77764
	* gcc/fortran/interface.c (gfc_compare_union_types): Null-guard map
	components.

	PR fortran/77764
	* gcc/testsuite/gfortran.dg/dec_union_8.f90: New testcase.

From-SVN: r240652

gcc/fortran/ChangeLog

 2016-09-30  Fritz Reese  <fritzoreese@gmail.com>
 
+	PR fortran/77764
+	* interface.c (gfc_compare_union_types): Null-guard map components.
+
+2016-09-30  Fritz Reese  <fritzoreese@gmail.com>
+
 	PR fortran/77782
 	* interface.c (gfc_compare_derived_types): Use gfc_compare_union_types
 	to compare union types.

gcc/fortran/interface.c

@@ -526,6 +526,7 @@ int
 gfc_compare_union_types (gfc_symbol *un1, gfc_symbol *un2)
 {
   gfc_component *map1, *map2, *cmp1, *cmp2;
+  gfc_symbol *map1_t, *map2_t;
 
   if (un1->attr.flavor != FL_UNION || un2->attr.flavor != FL_UNION)
     return 0;
@@ -541,16 +542,26 @@ gfc_compare_union_types (gfc_symbol *un1, gfc_symbol *un2)
      we compare the maps sequentially. */
   for (;;)
   {
-    cmp1 = map1->ts.u.derived->components;
-    cmp2 = map2->ts.u.derived->components;
+    map1_t = map1->ts.u.derived;
+    map2_t = map2->ts.u.derived;
+
+    cmp1 = map1_t->components;
+    cmp2 = map2_t->components;
+
+    /* Protect against null components.  */
+    if (map1_t->attr.zero_comp != map2_t->attr.zero_comp)
+      return 0;
+
+    if (map1_t->attr.zero_comp)
+      return 1;
+
     for (;;)
     {
       /* No two fields will ever point to the same map type unless they are
          the same component, because one map field is created with its type
          declaration. Therefore don't worry about recursion here. */
       /* TODO: worry about recursion into parent types of the unions? */
-      if (compare_components (cmp1, cmp2,
-            map1->ts.u.derived, map2->ts.u.derived) == 0)
+      if (compare_components (cmp1, cmp2, map1_t, map2_t) == 0)
         return 0;
 
       cmp1 = cmp1->next;

gcc/testsuite/ChangeLog

 2016-09-30  Fritz Reese  <fritzoreese@gmail.com>
 
+	PR fortran/77764
+	* gfortran.dg/dec_union_8.f90: New testcase.
+
+2016-09-30  Fritz Reese  <fritzoreese@gmail.com>
+
 	PR fortran/77782
 	* gfortran.dg/dec_structure_16.f90: New testcase.
 

gcc/testsuite/gfortran.dg/dec_union_8.f90

+! { dg-do compile }
+! { dg-options "-fdec-structure" }
+!
+! PR fortran/77764
+!
+! Test an ICE due to a map with zero components.
+!
+
+program p
+
+structure /s1/
+  union
+    map
+    end map
+    map
+      real :: a = 2.0
+    end map
+  end union
+end structure
+
+end