Sema: Fix for archetypes leaking through when resolving generic type alias

Also make the existing assertion for this stricter. Previously,
we were calling hasArchetype() on a GenericFunctionType, which
is always false (along with hasTypeParameter()) since generic
function types don't have any free type parameters in them.

Fixes <rdar://problem/27405113>.

lib/Sema/TypeCheckGeneric.cpp

@@ -638,6 +638,11 @@ void TypeChecker::configureInterfaceType(AbstractFunctionDecl *func) {
     if (i == 0 && func->hasThrows())
       info = info.withThrows();
 
+    assert(!argTy->hasArchetype());
+    assert(!funcTy->hasArchetype());
+    if (initFuncTy)
+      assert(!initFuncTy->hasArchetype());
+
     if (sig && i == e-1) {
       funcTy = GenericFunctionType::get(sig, argTy, funcTy, info);
       if (initFuncTy)
@@ -650,12 +655,9 @@ void TypeChecker::configureInterfaceType(AbstractFunctionDecl *func) {
   }
 
   // Record the interface type.
-  assert(!funcTy->hasArchetype());
   func->setInterfaceType(funcTy);
-  if (initFuncTy) {
+  if (initFuncTy)
-    assert(!initFuncTy->hasArchetype());
     cast<ConstructorDecl>(func)->setInitializerInterfaceType(initFuncTy);
-  }
 
   if (func->getGenericParams()) {
     // Collect all generic params referenced in parameter types,

lib/Sema/TypeCheckType.cpp

@@ -519,8 +519,7 @@ Type TypeChecker::applyUnboundGenericArguments(
     if (auto outerSig = TAD->getDeclContext()->getGenericSignatureOfContext()) {
       for (auto outerParam : outerSig->getGenericParams()) {
         subs[outerParam->getCanonicalType().getPointer()] =
-            ArchetypeBuilder::mapTypeIntoContext(TAD->getDeclContext(),
+            resolver->resolveGenericTypeParamType(outerParam);
-                                                 outerParam);
       }
     }
 

test/decl/typealias/generic.swift

@@ -164,6 +164,12 @@ class GenericClass<T> {
   }
 }
 
+let gc = GenericClass<Double>()
+let fn: MyType<Double, Int> = gc.testCapture(s: 1, t: 1.0)
+
+func use<T>(_ t: T) {}
+use(fn)
+
 // Make sure we apply base substitutions to the interface type of the typealias
 class ConcreteClass : GenericClass<String> {
   func testSubstitutedCapture1<S>(s: S, t: String) -> TA<S> {