[CodeCompleiton] Don't hide members for unresolved base types

Don't filter out members if the base type has unresolved types.

Previously, initializers used to be hidden if the type has 'where'
requirements on the generic parameters.

This patch enables initializer completion for `SwiftUI.ForEach`.

rdar://problem/49480808

Author: rintaro

lib/Sema/CSGen.cpp

@@ -3791,7 +3791,8 @@ bool swift::isExtensionApplied(const DeclContext *DC, Type BaseTy,
                                const ExtensionDecl *ED) {
   // We can't do anything if the base type has unbound generic parameters.
   // We can't leak type variables into another constraint system.
-  if (BaseTy->hasTypeVariable() || BaseTy->hasUnboundGenericType())
+  if (BaseTy->hasTypeVariable() || BaseTy->hasUnboundGenericType() ||
+      BaseTy->hasUnresolvedType() || BaseTy->hasError())
     return true;
 
   if (!ED->isConstrainedExtension())
@@ -3811,7 +3812,8 @@ bool swift::isMemberDeclApplied(const DeclContext *DC, Type BaseTy,
                                 const ValueDecl *VD) {
   // We can't leak type variables into another constraint system.
   // We can't do anything if the base type has unbound generic parameters.
-  if (BaseTy->hasTypeVariable() || BaseTy->hasUnboundGenericType())
+  if (BaseTy->hasTypeVariable() || BaseTy->hasUnboundGenericType()||
+      BaseTy->hasUnresolvedType() || BaseTy->hasError())
     return true;
 
   const GenericContext *genericDecl = VD->getAsGenericContext();

test/IDE/complete_constructor.swift

@@ -52,6 +52,7 @@
 
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=DEPENDENT_IN_CLOSURE_1 | %FileCheck %s -check-prefix=DEPENDENT_IN_CLOSURE_1
 // RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=DEPENDENT_IN_CLOSURE_2 | %FileCheck %s -check-prefix=DEPENDENT_IN_CLOSURE_2
+// RUN: %target-swift-ide-test -code-completion -source-filename %s -code-completion-token=INIT_WITH_UNRESOLVEDTYPE_1 | %FileCheck %s -check-prefix=INIT_WITH_UNRESOLVEDTYPE_1
 
 func freeFunc() {}
 
@@ -396,3 +397,16 @@ func testDependentTypeInClosure() {
 // DEPENDENT_IN_CLOSURE_2-DAG: Decl[Constructor]/CurrNominal:      init({#arg: _#}, {#fn: () -> _.Content##() -> _.Content#})[#DependentTypeInClosure<_>#]; name=init(arg: _, fn: () -> _.Content)
 // DEPENDENT_IN_CLOSURE_2: End completions
 }
+struct InitWithUnresolved<Data: DataType> where Data.Content: Comparable {
+  init(arg: Data, fn: (Data.Content) -> Void) {}
+}
+extension InitWithUnresolved where Self.Data: Comparable {
+  init(arg2: Data) {}
+}
+func testInitWithUnresolved() {
+  let _ = InitWithUnresolved(#^INIT_WITH_UNRESOLVEDTYPE_1^#
+// INIT_WITH_UNRESOLVEDTYPE_1: Begin completions, 2 items
+// INIT_WITH_UNRESOLVEDTYPE_1-DAG: Decl[Constructor]/CurrNominal:      ['(']{#arg: _#}, {#fn: (_.Content) -> Void##(_.Content) -> Void#}[')'][#InitWithUnresolved<_>#];
+// INIT_WITH_UNRESOLVEDTYPE_1-DAG: Decl[Constructor]/CurrNominal:      ['(']{#arg2: _#}[')'][#InitWithUnresolved<_>#];
+// INIT_WITH_UNRESOLVEDTYPE_1: End completions
+}