PR c++/80227 - SFINAE and negative array size.

	* decl.c (compute_array_index_type): Use
	build_converted_constant_expr and valid_constant_size_p.

From-SVN: r258604

gcc/cp/ChangeLog

 2018-03-16  Jason Merrill  <jason@redhat.com>
 
+	PR c++/80227 - SFINAE and negative array size.
+	* decl.c (compute_array_index_type): Use
+	build_converted_constant_expr and valid_constant_size_p.
+
 	PR c++/84906 - silent wrong code with ambiguous conversion.
 	* call.c (build_user_type_conversion_1): Set need_temporary_p on
 	ambiguous conversion.

gcc/cp/decl.c

@@ -9514,8 +9514,6 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
 
   if (!type_dependent_expression_p (size))
     {
-      tree type = TREE_TYPE (size);
-
       size = mark_rvalue_use (size);
 
       if (cxx_dialect < cxx11 && TREE_CODE (size) == NOP_EXPR
@@ -9525,29 +9523,8 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
       else
 	{
 	  size = instantiate_non_dependent_expr_sfinae (size, complain);
-
-	  if (CLASS_TYPE_P (type)
-	      && CLASSTYPE_LITERAL_P (type))
-	    {
-	      size = build_expr_type_conversion (WANT_INT, size, true);
-	      if (!size)
-		{
-		  if (!(complain & tf_error))
-		    return error_mark_node;
-		  if (name)
-		    error ("size of array %qD has non-integral type %qT",
-			   name, type);
-		  else
-		    error ("size of array has non-integral type %qT", type);
-		  size = integer_one_node;
-		}
-	      if (size == error_mark_node)
-		return error_mark_node;
-	      type = TREE_TYPE (size);
-	    }
-
-	  if (INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type))
-	    size = maybe_constant_value (size);
+	  size = build_converted_constant_expr (size_type_node, size, complain);
+	  size = maybe_constant_value (size);
 
 	  if (!TREE_CONSTANT (size))
 	    size = osize;
@@ -9557,6 +9534,7 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
 	return error_mark_node;
 
       /* The array bound must be an integer type.  */
+      tree type = TREE_TYPE (size);
       if (!INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (type))
 	{
 	  if (!(complain & tf_error))
@@ -9566,7 +9544,6 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
 	  else
 	    error ("size of array has non-integral type %qT", type);
 	  size = integer_one_node;
-	  type = TREE_TYPE (size);
 	}
     }
 
@@ -9604,15 +9581,12 @@ compute_array_index_type (tree name, tree size, tsubst_flags_t complain)
   /* Normally, the array-bound will be a constant.  */
   if (TREE_CODE (size) == INTEGER_CST)
     {
-      /* Check to see if the array bound overflowed.  Make that an
-	 error, no matter how generous we're being.  */
-      constant_expression_error (size);
-
       /* An array must have a positive number of elements.  */
-      if (tree_int_cst_lt (size, integer_zero_node))
+      if (!valid_constant_size_p (size))
 	{
 	  if (!(complain & tf_error))
 	    return error_mark_node;
+
 	  if (name)
 	    error ("size of array %qD is negative", name);
 	  else

gcc/testsuite/g++.dg/cpp0x/fntmpdefarg8.C

+// PR c++/80227
+// { dg-do compile { target c++11 } }
+
+template <class T>
+int foo (T);
+
+template <class T, class U = T [sizeof (T) - 5]>
+int foo (T, U* = 0);
+
+int i = foo (123);

gcc/testsuite/g++.dg/gomp/pr47963.C

@@ -5,7 +5,7 @@
 void
 foo (float n)
 {
-  int A[n][n];	// { dg-error "has non-integral type" }
+  int A[n][n];	// { dg-error "has non-integral type|converted constant expression" }
 #pragma omp parallel private(A)
   ;
 }

gcc/testsuite/g++.dg/init/new37.C

@@ -32,7 +32,7 @@ template <typename T>
 void *
 callnew_fail_3()
 {
-  return new T[2][T::n]; // { dg-error "size of array has non-integral type" }
+  return new T[2][T::n]; // { dg-error "size of array has non-integral type|converted constant expression" }
 }
 
 struct T1 {

gcc/testsuite/g++.dg/ubsan/pr81530.C

@@ -2,5 +2,4 @@
 /* { dg-do compile } */
 /* { dg-options "-fsanitize=undefined" } */
 
-int a[(long) 4e20]; /* { dg-error "overflow in constant expression" } */
-/* { dg-error "size of array .a. is too large" "" { target *-*-* } .-1 } */
+int a[(long) 4e20]; /* { dg-error "size of array .a. is (too large|negative)" } */