Created attachment 22126 [details]
crash-cases.tar.xz

Yeah, I added a comment about this to https://reviews.llvm.org/rC363086.  Reduced test case (which asserts with 8.0.0 and 8.0.1, but not trunk after r363086): 

// clang -cc1 -triple x86_64-- -S -std=c++17 RecordIO-min.cpp
// Assertion failed: (!Init->isValueDependent()), function checkInitIsICE,
// file tools/clang/lib/AST/Decl.cpp, line 2342.
template <int> struct a;
template <class b, class> struct c {
  static constexpr int f = b ::d;
  c(a<f>);
};
template <class e, class g = int> c(e)->c<e, g>;

The question is whether it is feasible to backport the whole of r363086, which is fairly disruptive, or if there is another, smaller fix.