template without a corresponding parameter pack, don't immediately
substitute the alias template. This is under discussion in the C++
committee, and may become ill-formed, but for now we match GCC.
llvm-svn: 149697
template. Such pack expansions can easily fail at template
instantiation time, if the expanded parameter packs are of the wrong
length. Fixes <rdar://problem/10040867>, PR9021, and the example that
came up today at Going Native.
llvm-svn: 149685