[Serialization] Recover from failures in ModuleFile::lookupClassMembers

Access to a missing member on an AnyObject triggers a typo correction
that looks at all class members in imported modules. Make sure it
recovers from deserializing members referencing implementation-only
imported types.

rdar://79427805

lib/Serialization/ModuleFile.cpp

@@ -794,7 +794,13 @@ void ModuleFile::lookupClassMembers(ImportPath::Access accessPath,
   if (!accessPath.empty()) {
     for (const auto &list : Core->ClassMembersForDynamicLookup->data()) {
       for (auto item : list) {
-        auto vd = cast<ValueDecl>(getDecl(item.second));
+        auto decl = getDeclChecked(item.second);
+        if (!decl) {
+          llvm::consumeError(decl.takeError());
+          continue;
+        }
+
+        auto vd = cast<ValueDecl>(decl.get());
         auto dc = vd->getDeclContext();
         while (!dc->getParent()->isModuleScopeContext())
           dc = dc->getParent();
@@ -808,10 +814,17 @@ void ModuleFile::lookupClassMembers(ImportPath::Access accessPath,
   }
 
   for (const auto &list : Core->ClassMembersForDynamicLookup->data()) {
-    for (auto item : list)
+    for (auto item : list) {
-      consumer.foundDecl(cast<ValueDecl>(getDecl(item.second)),
+        auto decl = getDeclChecked(item.second);
+        if (!decl) {
+          llvm::consumeError(decl.takeError());
+          continue;
+        }
+
+      consumer.foundDecl(cast<ValueDecl>(decl.get()),
                          DeclVisibilityKind::DynamicLookup,
                          DynamicLookupInfo::AnyObject);
+    }
   }
 }
 

test/Serialization/Recovery/implementation-only-missing.swift

@@ -12,8 +12,9 @@
 //// The client app should build OK without the private module. Removing the
 //// private module is superfluous but makes sure that it's not somehow loaded.
 // RUN: rm %t/private_lib.swiftmodule
-// RUN: %target-swift-frontend -typecheck -DCLIENT_APP -primary-file %s -I %t -index-system-modules -index-store-path %t
+// RUN: %target-swift-frontend -typecheck -DCLIENT_APP %s -I %t -index-system-modules -index-store-path %t
-// RUN: %target-swift-frontend -emit-sil -DCLIENT_APP -primary-file %s -I %t -module-name client
+// RUN: %target-swift-frontend -typecheck -DCLIENT_APP %s -I %t -D FAIL_TYPECHECK -verify
+// RUN: %target-swift-frontend -emit-sil -DCLIENT_APP %s -I %t -module-name client
 
 //// Printing the public module should not crash when checking for overrides of
 //// methods from the private module.
@@ -46,6 +47,8 @@ public protocol HiddenProtocolWithOverride {
   func hiddenOverride()
 }
 
+public class HiddenClass {}
+
 #elseif PUBLIC_LIB
 
 @_implementationOnly import private_lib
@@ -91,6 +94,10 @@ public struct PublicStructConformsToHiddenProtocol: RefinesHiddenProtocol {
   public init() { }
 }
 
+public class SomeClass {
+    func funcUsingIoiType(_ a: HiddenClass) {}
+}
+
 #elseif CLIENT_APP
 
 import public_lib
@@ -101,4 +108,12 @@ print(s.nonWrappedVar)
 var p = PublicStructConformsToHiddenProtocol()
 print(p)
 
+#if FAIL_TYPECHECK
+    // Access to a missing member on an AnyObject triggers a typo correction
+    // that looks at *all* class members. rdar://79427805
+    class ClassUnrelatedToSomeClass {}
+    var something = ClassUnrelatedToSomeClass() as AnyObject
+    something.triggerTypoCorrection = 123 // expected-error {{value of type 'AnyObject' has no member 'triggerTypoCorrection'}}
+#endif
+
 #endif