Thinko in the tsubst_attributes logic. Tested x86_64-pc-linux-gnu, applying to trunk.
commit 9460ce06baf4d47d44aa7111f991bb50e6644f67 Author: Jason Merrill <ja...@redhat.com> Date: Thu Jul 14 10:56:25 2016 -0400
PR c++/71513 - alignas on member enum in template * pt.c (tsubst_attributes): Fix loop logic. diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index de70fb2..1fbf546 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -9713,20 +9713,23 @@ tsubst_attributes (tree attributes, tree args, } if (last_dep) - for (tree *p = &attributes; *p; p = &TREE_CHAIN (*p)) + for (tree *p = &attributes; *p; ) { tree t = *p; if (ATTR_IS_DEPENDENT (t)) { tree subst = tsubst_attribute (t, NULL, args, complain, in_decl); - if (subst == t) - continue; - *p = subst; - do - p = &TREE_CHAIN (*p); - while (*p); - *p = TREE_CHAIN (t); + if (subst != t) + { + *p = subst; + do + p = &TREE_CHAIN (*p); + while (*p); + *p = TREE_CHAIN (t); + continue; + } } + p = &TREE_CHAIN (*p); } return attributes; diff --git a/gcc/testsuite/g++.dg/cpp0x/alignas7.C b/gcc/testsuite/g++.dg/cpp0x/alignas7.C new file mode 100644 index 0000000..a209250 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/alignas7.C @@ -0,0 +1,13 @@ +// PR c++/71513 +// { dg-do compile { target c++11 } } + +template < int N, typename T > +struct A +{ + enum alignas (N) E : T; +}; + +#define SA(X) static_assert((X), #X) + +constexpr int al = alignof(double); +SA(alignof(A<al,char>::E) == al);