Fix the GUID type not found error on Windows

Predefined declarations (like _GUID) are special forward declarations
inserted by Clang and aren't serialized into the pcm and their
definition pointers aren't retained across serialization and
deserialization, which causes this type not found error. Avoid putting
non-defining predefined declarations into the swift lookup table when
their definitions exist in the same module so that the definitions
will be associated with the base name and avoid this error.

Author: hjyamauchi

lib/ClangImporter/SwiftLookupTable.cpp

@@ -2180,6 +2180,17 @@ void SwiftLookupTableWriter::populateTableWithDecl(SwiftLookupTable &table,
   if (decl->isFromASTFile())
     return;
 
+  // Exclude a predefined declaration that's not a definition if its
+  // definition exists in the same module so that the definition will
+  // be associated with the base name, noting predefined declarations
+  // won't be serialized into the pcm and its state including its
+  // definition pointer won't be reconstructed after deserialization,
+  // which would cause a type not found error.
+  if (Writer.isDeclPredefined(decl))
+    if (auto tagDecl = dyn_cast<clang::TagDecl>(decl))
+      if (!tagDecl->isThisDeclarationADefinition() && tagDecl->getDefinition())
+        return;
+
   // Iterate into extern "C" {} type declarations.
   if (auto linkageDecl = dyn_cast<clang::LinkageSpecDecl>(decl)) {
     for (auto *decl : linkageDecl->noload_decls()) {

test/Serialization/guid-defined-in-module.swift

@@ -0,0 +1,32 @@
+// REQUIRES: OS=windows-msvc
+
+// Test that a struct named _GUID is found and usable in C++ when it is
+// defined, not just forward declared, within the same Clang module where
+// _GUID is specially-handled as a predefined (forward) declaration on
+// Windows.
+
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+// RUN: %target-swift-frontend -c -primary-file %t/Test.swift -cxx-interoperability-mode=default -I %t -Xcc -fmodule-map-file=%t/module.modulemap -Xcc -I -Xcc %t -module-name Test -o %t/Test.swift.o -module-cache-path %t/module-cache
+
+//--- Test.swift
+import TestMod
+
+extension TestMod._GUID {
+  public func m() -> Int { 42 }
+}
+
+//--- test.h
+#ifndef TEST_H
+#define TEST_H
+
+typedef struct _GUID {
+  int Data;
+} GUID;
+
+#endif // TEST_H
+
+//--- module.modulemap
+module TestMod {
+  header "test.h"
+}

test/Serialization/wrapped-modularization-error-remarks.swift

@@ -1,10 +1,4 @@
 // RUN: %empty-directory(%t)
 // RUN: %target-swift-frontend -emit-module %S/Inputs/wrapped-modularization-error-remarks/A/A.swift -cxx-interoperability-mode=default -Xcc -fmodule-map-file=%S/Inputs/wrapped-modularization-error-remarks/CxxLib/include/module.modulemap -Xcc -I -Xcc %S/Inputs/wrapped-modularization-error-remarks/CxxLib/include -module-name A -o %t/A.swiftmodule
-// RUN: not %target-swift-frontend -c -primary-file %S/Inputs/wrapped-modularization-error-remarks/B/B.swift -cxx-interoperability-mode=default -I %t -Xcc -fmodule-map-file=%S/Inputs/wrapped-modularization-error-remarks/CxxLib/include/module.modulemap -Xcc -I -Xcc %S/Inputs/wrapped-modularization-error-remarks/CxxLib/include -module-name B -o %t/B.swift.o -Rmodule-recovery 2>&1 | %FileCheck %s
+// RUN: %target-swift-frontend -c -primary-file %S/Inputs/wrapped-modularization-error-remarks/B/B.swift -cxx-interoperability-mode=default -I %t -Xcc -fmodule-map-file=%S/Inputs/wrapped-modularization-error-remarks/CxxLib/include/module.modulemap -Xcc -I -Xcc %S/Inputs/wrapped-modularization-error-remarks/CxxLib/include -module-name B -o %t/B.swift.o -Rmodule-recovery
 // REQUIRES: OS=windows-msvc
-
-// Check that the diagnostics/remark from the wrapped ModularizationError is emitted.
-// CHECK: remark: reference to type '_GUID' broken by a context change; '_GUID' is not found, it was expected to be in 'CxxLib'
-// CHECK: note: could not deserialize type for 'queryInterface'
-// CHECK: error: cannot inherit from class 'Window' because it has overridable members that could not be loaded
-// CHECK: note: could not deserialize 'queryInterface'