SIL: Fix another bug in verifyDynamicPackIndexStructuralEquality()

Fixes rdar://problem/109911237.

Author: slavapestov

lib/SIL/Verifier/SILVerifier.cpp

@@ -5757,8 +5757,15 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
       // Provide substitution functions that replace the pack archetypes
       // we found above with the corresponding lane of the pack substitution.
       auto substTypes = [&](SubstitutableType *type) -> Type {
+        auto archetype = dyn_cast<ElementArchetypeType>(type);
+        if (!archetype)
+          return type;
+        if (!archetype->isRoot())
+          return Type();
+
         auto it = allOpened.find(type->getCanonicalType());
-        if (it == allOpened.end()) return Type();
+        assert(it != allOpened.end());
+
         auto pack = it->second;
         auto packElementType = pack.getElementType(componentIndex);
         if (auto exp = dyn_cast<PackExpansionType>(packElementType)) {

test/SILGen/pack_expansion_type.swift

@@ -46,3 +46,7 @@ func variadicMetatypes<each T>(_: repeat each T) {
 // CHECK-LABEL: sil [ossa] @$s19pack_expansion_type18sameExpansionTwice2us05more_G02vsyxxQp_xxQpq_q_QptRvzRv_r0_lF : $@convention(thin) <each U, each V> (@pack_guaranteed Pack{repeat each U}, @pack_guaranteed Pack{repeat each U}, @pack_guaranteed Pack{repeat each V}) -> () {
 public func sameExpansionTwice<each U, each V>(us: repeat each U, more_us: repeat each U, vs: repeat each V) {}
 
+// SILVerifier bug
+public func nonPackAndPackParameterInExpansion<each T, U, V>(t: repeat each T, u: U, v: V) -> (repeat (each T, U, V)) {
+  return (repeat (each t, u, v))
+}