re PR c++/84540 (ICE with alignas in variadic template)

/cp
2018-02-26  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84540
	* pt.c (tsubst_attributes): Handle correctly tsubst_attribute
	returning NULL_TREE.
	(apply_late_template_attributes): Likewise.

/testsuite
2018-02-26  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/84540
	* g++.dg/cpp0x/alignas14.C: New.
	* g++.dg/cpp0x/alignas15.C: Likewise.

From-SVN: r258012

gcc/cp/ChangeLog

+2018-02-26  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/84540
+	* pt.c (tsubst_attributes): Handle correctly tsubst_attribute
+	returning NULL_TREE.
+	(apply_late_template_attributes): Likewise.
+
 2018-02-26  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/84557

gcc/cp/pt.c

@@ -10245,9 +10245,8 @@ tsubst_attributes (tree attributes, tree args,
 	    if (subst != t)
 	      {
 		*p = subst;
-		do
+		while (*p)
 		  p = &TREE_CHAIN (*p);
-		while (*p);
 		*p = TREE_CHAIN (t);
 		continue;
 	      }
@@ -10314,9 +10313,8 @@ apply_late_template_attributes (tree *decl_p, tree attributes, int attr_flags,
 	      *p = TREE_CHAIN (t);
 	      TREE_CHAIN (t) = NULL_TREE;
 	      *q = tsubst_attribute (t, decl_p, args, complain, in_decl);
-	      do
+	      while (*q)
 		q = &TREE_CHAIN (*q);
-	      while (*q);
 	    }
 	  else
 	    p = &TREE_CHAIN (t);

gcc/testsuite/ChangeLog

+2018-02-26  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/84540
+	* g++.dg/cpp0x/alignas14.C: New.
+	* g++.dg/cpp0x/alignas15.C: Likewise.
+
 2018-02-26  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/84557

gcc/testsuite/g++.dg/cpp0x/alignas14.C

+// PR c++/84540
+// { dg-do compile { target c++11 } }
+
+template<typename... T> struct alignas(alignof(T)...) A {};
+
+A<> a;

gcc/testsuite/g++.dg/cpp0x/alignas15.C

+// PR c++/84540
+// { dg-do compile { target c++11 } }
+
+template<typename... T> struct A { enum alignas(alignof(T)...) E {}; };
+
+A<> a;