[SILGen] tweak LogicalKeyPathApplicationComponent

A baked-in assumption was that the generic parameters of the KeyPath
family of types have no conformance requirements. That's no longer the
case with NoncopyableGenerics, so we need to dig up conformances when
forming the substitution map, as-needed.

Author: kavon

lib/SILGen/SILGenLValue.cpp

@@ -2320,8 +2320,9 @@ namespace {
 
       auto keyPathValue = KeyPath;
 
-      SmallVector<Type, 2> typeArgs;
-      typeArgs.push_back(BaseFormalType);
+      GenericSignature sig;
+      TypeSubstitutionMap map;
+
       if (TypeKind == KPTK_AnyKeyPath) {
         projectFn = SGF.getASTContext().getGetAtAnyKeyPath();
       } else if (TypeKind == KPTK_PartialKeyPath) {
@@ -2330,21 +2331,31 @@ namespace {
                  TypeKind == KPTK_WritableKeyPath ||
                  TypeKind == KPTK_ReferenceWritableKeyPath) {
         projectFn = SGF.getASTContext().getGetAtKeyPath();
+        sig = projectFn->getGenericSignature();
+        auto genericParams = sig.getGenericParams();
 
         auto keyPathTy = keyPathValue.getType().castTo<BoundGenericType>();
         assert(keyPathTy->getGenericArgs().size() == 2);
         assert(keyPathTy->getGenericArgs()[0]->getCanonicalType() ==
                BaseFormalType->getCanonicalType());
-        typeArgs.push_back(keyPathTy->getGenericArgs()[1]);
+        assert(genericParams.size() == 2);
+        auto secondGenParam = genericParams[1]->getCanonicalType()
+                                              ->castTo<SubstitutableType>();
+        map[secondGenParam] = keyPathTy->getGenericArgs()[1];
 
         keyPathValue = emitUpcastToKeyPath(SGF, loc, TypeKind, keyPathValue);
       } else {
         llvm_unreachable("bad key path kind for this component");
       }
 
-      auto subs = SubstitutionMap::get(projectFn->getGenericSignature(),
-                                       ArrayRef<Type>(typeArgs),
-                                       ArrayRef<ProtocolConformanceRef>());
+      sig = projectFn->getGenericSignature();
+      auto firstGenParam = sig.getGenericParams()[0]->getCanonicalType()
+                                                  ->castTo<SubstitutableType>();
+      map[firstGenParam] = BaseFormalType;
+
+      auto subs = SubstitutionMap::get(sig,
+                  QueryTypeSubstitutionMap{map},
+                  LookUpConformanceInModule{SGF.getModule().getSwiftModule()});
 
       base = makeBaseConsumableMaterializedRValue(SGF, loc, base);