re PR c++/19989 (Inconsistency with zero-sized arrays)

PR c++/19989
cp/pt.c (tsubst): Accept zero-length array if tf_error is set
in complain flags.  Change error message for negative-
length array.
testsuite/g++.dg/ext/array2.C: New test.
testsuite/g++.dg/template/dependent-name3.C: New test.
testsuite/g++.dg/template/dependent-name4.C: New test.
testsuite/g++.dg/template/sfinae2.C: New test.

From-SVN: r106468

gcc/cp/ChangeLog

@@ -1,3 +1,10 @@
+2005-11-03  Josh Conner  <jconner@apple.com>
+
+	PR c++/19989
+	pt.c (tsubst): Accept zero-length array if tf_error is set
+	in complain flags.  Change error message for negative-
+	length array.
+
 2005-11-04  Joseph S. Myers  <joseph@codesourcery.com>
 
 	* cp-tree.h (cp_cpp_error), error.c (cp_cpp_error): Take va_list*

gcc/cp/pt.c

@@ -7083,25 +7083,24 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	max = tsubst_template_arg (omax, args, complain, in_decl);
 	max = fold_decl_constant_value (max);
 
-	if (integer_zerop (omax))
-	  {
-	    /* Still allow an explicit array of size zero.  */
-	    if (pedantic)
-	      pedwarn ("creating array with size zero");
-	  }
-	else if (integer_zerop (max)
-		 || (TREE_CODE (max) == INTEGER_CST
-		     && INT_CST_LT (max, integer_zero_node)))
-	  {
-	    /* [temp.deduct]
+	/* [temp.deduct]
 
-	       Type deduction may fail for any of the following
-	       reasons:
+	   Type deduction may fail for any of the following
+	   reasons:
 
-		 Attempting to create an array with a size that is
-		 zero or negative.  */
+	     Attempting to create an array with a size that is
+	     zero or negative.  */
+	if (integer_zerop (max) && !(complain & tf_error))
+	  /* We must fail if performing argument deduction (as
+	     indicated by the state of complain), so that
+	     another substitution can be found.  */
+	  return error_mark_node;
+
+	else if (TREE_CODE (max) == INTEGER_CST
+		 && INT_CST_LT (max, integer_zero_node))
+	  {
 	    if (complain & tf_error)
-	      error ("creating array with size zero (%qE)", max);
+	      error ("creating array with negative size (%qE)", max);
 
 	    return error_mark_node;
 	  }

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2005-11-03  Josh Conner  <jconner@apple.com>
+
+	PR c++/19989
+	g++.dg/ext/array2.C: New test.
+	g++.dg/template/dependent-name3.C: New test.
+	g++.dg/template/dependent-name4.C: New test.
+	g++.dg/template/sfinae2.C: New test.
+
 2005-11-03  Andrew Pinski  <pinskia@physics.uc.edu>
 
 	PR preprocessor/22042

gcc/testsuite/g++.dg/ext/array2.C

@@ -0,0 +1,18 @@
+// { dg-do compile }
+
+// Avoid -pedantic-error default
+// { dg-options "" }
+ 
+// PR 19989 - dependent array of size 0 fails to compile.
+
+template<int I> struct A
+{
+  static const int zero = 0;
+};
+
+template<int N> struct B
+{
+  int x[A<N>::zero];
+};
+
+B<0> b;

gcc/testsuite/g++.dg/template/dependent-name3.C

@@ -0,0 +1,17 @@
+// { dg-do compile }
+
+// Dependent arrays of invalid size generate appropriate error messages
+
+template<int I> struct A
+{
+  static const int zero = 0;
+  static const int minus_one = -1;
+};
+
+template<int N> struct B
+{
+  int x[A<N>::zero];       // { dg-error "zero" }
+  int y[A<N>::minus_one];  // { dg-error "negative" }
+};
+
+B<0> b;

gcc/testsuite/g++.dg/template/dependent-name4.C

@@ -0,0 +1,15 @@
+// { dg-do compile }
+
+// Dependent arrays of invalid size cause template instantiation failure.
+
+// We'll get an error message (duplicate matching templates) if the first
+//  pattern is incorrectly allowed to match.
+
+template<int M> void foobar (int (*) [M] = 0 );
+template<int M> void foobar ( );
+
+void fn (void)
+{
+  foobar<0>();
+  foobar<-1>();
+}

gcc/testsuite/g++.dg/template/sfinae2.C

@@ -0,0 +1,17 @@
+// PR c++/19989
+// Don't instantiate a function template if it would generate an
+//   array of size zero.
+
+// { dg-do compile }
+
+template<int T> struct cl {
+  const static int value = T;
+};
+
+template<int I> void fn (char (*) [cl<I>::value] = 0 );
+
+void foo (void)
+{
+  fn<0> ();  // { dg-error "no matching function" }
+}
+