[C++ PATCH] Fix error handling in build_enumerator (PR c++/37389)

[Jakub Jelinek]

Hi!

The comment in build_enumerator says "We can safely assume that the previous
value is an INTEGER_CST", but that's clearly not the case.  Just a few lines
below this we set value to error_mark_node (if it overflowed) and in another
place later on value can be set to NULL in C++0x overflow case.
This patch handles those two values.

Ok for trunk/4.3?

2008-09-09  Jakub Jelinek  <jakub@redhat.com>

	PR c++/37389
	* decl.c (build_enumerator): Handle previous value's DECL_INITIAL
	being NULL or error_mark_node.

	* g++.dg/parse/enum4.C: New test.

--- gcc/cp/decl.c.jj	2008-09-09 09:31:02.000000000 +0200
+++ gcc/cp/decl.c	2008-09-09 09:34:29.000000000 +0200
@@ -11134,21 +11134,26 @@ build_enumerator (tree name, tree value,
 	      tree prev_value;
 	      bool overflowed;
 
-	      /* The next value is the previous value plus one.  We can
-		 safely assume that the previous value is an INTEGER_CST.
+	      /* The next value is the previous value plus one.
 		 add_double doesn't know the type of the target expression,
 		 so we must check with int_fits_type_p as well.  */
 	      prev_value = DECL_INITIAL (TREE_VALUE (TYPE_VALUES (enumtype)));
-	      overflowed = add_double (TREE_INT_CST_LOW (prev_value),
-				       TREE_INT_CST_HIGH (prev_value),
-				       1, 0, &lo, &hi);
-	      value = build_int_cst_wide (TREE_TYPE (prev_value), lo, hi);
-	      overflowed |= !int_fits_type_p (value, TREE_TYPE (prev_value));
-
-	      if (overflowed)
+	      if (prev_value == NULL_TREE || prev_value == error_mark_node)
+		value = error_mark_node;
+	      else
 		{
-		  error ("overflow in enumeration values at %qD", name);
-		  value = error_mark_node;
+		  overflowed = add_double (TREE_INT_CST_LOW (prev_value),
+					   TREE_INT_CST_HIGH (prev_value),
+					   1, 0, &lo, &hi);
+		  value = build_int_cst_wide (TREE_TYPE (prev_value), lo, hi);
+		  overflowed
+		    |= !int_fits_type_p (value, TREE_TYPE (prev_value));
+
+		  if (overflowed)
+		    {
+		      error ("overflow in enumeration values at %qD", name);
+		      value = error_mark_node;
+		    }
 		}
 	    }
 	  else
--- gcc/testsuite/g++.dg/parse/enum4.C.jj	2008-09-09 09:37:33.000000000 +0200
+++ gcc/testsuite/g++.dg/parse/enum4.C	2008-09-09 09:37:10.000000000 +0200
@@ -0,0 +1,10 @@
+// PR c++/37389
+// { dg-do compile }
+// { dg-options "-std=gnu++98" }
+
+enum
+{
+  A = 9223372036854775807ULL * 2 + 1,
+  B = B0,	// { dg-error "was not declared|overflow" }
+  C = C0	// { dg-error "was not declared" }
+};

	Jakub