Fix the issue that struct _GUID isn't found on Windows

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'